java 通过TCPUDP 协议实现多人聊天，点对点，文件传送-----分服务器端和客户端

java 通过TCPUDP 协议实现多人聊天，点对点，文件传送-----分服务器端和客户端

 

　　启动界面如下图：

 

 

 

首先启动服务器：

 

客户端登陆，登陆成功后为：

默认发送是全部用户，是多人发送。　　当在边列表里面选择了用户后，可以与此用户建立点对点链接进行聊天，可以发送文件。

 用户在线离线状态会实时更新，如果离线，则存为离线消息。当下次上线的时候，会接受到离线消息

 从一个用户接受文件的同时，还可以接受从服务器发过来的文件

接受文件完成后，显示记录，并显示保存目录

消息发送演示

 服务器端代码：

import sun.misc.BASE64Encoder;

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.GridLayout;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.io.*;
import java.net.BindException;
import java.net.ServerSocket;
import java.net.Socket;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.StringTokenizer;

import javax.swing.DefaultListModel;
import javax.swing.JButton;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JList;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JSplitPane;
import javax.swing.JTextArea;
import javax.swing.JTextField;
import javax.swing.border.TitledBorder;
import javax.swing.event.ListSelectionEvent;
import javax.swing.event.ListSelectionListener;

public class Server {

    private JFrame frame;
    private JTextArea contentArea;
    private JTextField txt_message;
    private JTextField txt_max;
    private JTextField txt_port;
    private JButton btn_start;
    private JButton btn_stop;
    private JButton btn_send;
    private JButton btn_send_file;
    private JPanel northPanel;
    private JPanel southPanel;
    private JPanel sendPanel;
    private JScrollPane rightPanel;
    private JScrollPane leftPanel;
    private JScrollPane rightPanel2;
    private JSplitPane centerSplit;
    private JSplitPane centerSplit2;
    private JList userList;
    private JList all_userList;
    private DefaultListModel listModel;
    private static DefaultListModel all_listModel;

    private ServerSocket serverSocket;
    private ServerThread serverThread;
    private ArrayList<ClientThread> clients;//客户线程数组

    private boolean isStart = false;//标志服务器是否启动或关闭

    private int sendfor_who = 0;//监听左边jlist，保存给哪个用户发消息

    // 主方法,程序执行入口
    public static void main(String[] args) {

        new Server();

        try {
            Connection con = null; //定义一个MYSQL链接对象
            Class.forName("com.mysql.jdbc.Driver").newInstance();//MYSQL驱动
            con = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/server_db", "root", "root"); //链接本地MYSQL
            Statement stmt; //创建声明
            stmt = con.createStatement();

        } catch (Exception e) {
            System.out.print("MYSQL ERROR:" + e.getMessage());
        }
    }

    /**利用MD5进行加密
     * @param str  待加密的字符串
     * @return  加密后的字符串
     * @throws NoSuchAlgorithmException  没有这种产生消息摘要的算法
     * @throws UnsupportedEncodingException
     */
    public String EncoderByMd5(String str) throws NoSuchAlgorithmException, UnsupportedEncodingException {
        //确定计算方法
        MessageDigest md5=MessageDigest.getInstance("MD5");
        BASE64Encoder base64en = new BASE64Encoder();
        //加密后的字符串
        String newstr=base64en.encode(md5.digest(str.getBytes("utf-8")));
        return newstr;
    }

    /**判断用户密码是否正确
     * @param newpasswd  用户输入的密码
     * @param oldpasswd  数据库中存储的密码－－用户密码的摘要
     * @return
     * @throws NoSuchAlgorithmException
     * @throws UnsupportedEncodingException
     */
    public boolean checkpassword(String newpasswd,String oldpasswd) throws NoSuchAlgorithmException, UnsupportedEncodingException{
        if(EncoderByMd5(newpasswd).equals(oldpasswd))
            return true;
        else
            return false;
    }

    /**
     * 刚服务器突然关闭时，把所有用户状态置为离线
     */
    public void set_user_state_off() {
        try {
            Connection con = null; //定义一个MYSQL链接对象
            Class.forName("com.mysql.jdbc.Driver").newInstance();//MYSQL驱动
            con = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/server_db", "root", "root"); //链接本地MYSQL
            Statement stmt; //创建声明
            stmt = con.createStatement();

            int id = 0;
            String selectSql = "UPDATE user SET state = 0";
            stmt.executeUpdate(selectSql);
        } catch (Exception e) {
            System.out.print("MYSQL ERROR:" + e.getMessage());
        }
    }

    /**
     * 更新用户状态
     */
    public void user_name_update() {

        try {
            Connection con = null; //定义一个MYSQL链接对象
            Class.forName("com.mysql.jdbc.Driver").newInstance();//MYSQL驱动
            con = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/server_db", "root", "root"); //链接本地MYSQL
            Statement stmt; //创建声明
            stmt = con.createStatement();

            all_listModel.removeAllElements();
            all_listModel.addElement("全部用户");

            String username_db;
            int state = 0;
            //查询用户名
            String selectSql = "SELECT * FROM user";
            ResultSet selectRes = stmt.executeQuery(selectSql);
            while (selectRes.next()) { //循环输出结果集
                username_db = selectRes.getString("username");
                state = selectRes.getInt("state");
                if (state == 1) {
                    all_listModel.addElement(username_db + "---(在线)");
                }

            }

            selectRes = stmt.executeQuery(selectSql);
            while (selectRes.next()) { //循环输出结果集
                username_db = selectRes.getString("username");
                state = selectRes.getInt("state");
                if (state == 0) {
                    all_listModel.addElement(username_db + "---(离线)");
                }

            }
        } catch (Exception e) {
            System.out.print("MYSQL ERROR:" + e.getMessage());
        }

    }

    /**
     * 执行消息发送
     */
    public void send() {
        if (!isStart) {
            JOptionPane.showMessageDialog(frame, "服务器还未启动,不能发送消息！", "错误",
                    JOptionPane.ERROR_MESSAGE);
            return;
        }
//        if (clients.size() == 0) {
//            JOptionPane.showMessageDialog(frame, "没有用户在线,不能发送消息！", "错误",
//                    JOptionPane.ERROR_MESSAGE);
//            return;
//        }
        String message = txt_message.getText().trim();
        if (message == null || message.equals("")) {
            JOptionPane.showMessageDialog(frame, "消息不能为空！", "错误",
                    JOptionPane.ERROR_MESSAGE);
            return;
        }
        sendServerMessage(message, sendfor_who);// 群发服务器消息
        //contentArea.append("对  "+listModel.getElementAt(sendfor_who)+"  说：" + txt_message.getText() + "
");
        txt_message.setText(null);
    }

    // 构造放法
    public Server() {
        SelecTry selectIndex = new SelecTry();
        frame = new JFrame("服务器");
        contentArea = new JTextArea();
        contentArea.setEditable(false);
        contentArea.setForeground(Color.blue);
        txt_message = new JTextField();
        txt_max = new JTextField("30");
        txt_port = new JTextField("6666");
        btn_start = new JButton("启动");
        btn_stop = new JButton("停止");
        btn_send = new JButton("发送");
        btn_send_file = new JButton("文件");
        btn_stop.setEnabled(false);
        listModel = new DefaultListModel();
        all_listModel = new DefaultListModel();
        //listModel.addElement("全部用户");
        userList = new JList(all_listModel);//listModel
        userList.addListSelectionListener(selectIndex);

        user_name_update();//更新用户状态

//        all_userList = new JList(all_listModel);

        southPanel = new JPanel(new BorderLayout());
        sendPanel = new JPanel(new BorderLayout());
        southPanel.setBorder(new TitledBorder("写消息"));
        southPanel.add(txt_message, "Center");
        sendPanel.add(btn_send, BorderLayout.NORTH);
        sendPanel.add(btn_send_file, BorderLayout.SOUTH);

        southPanel.add(sendPanel, "East");

        leftPanel = new JScrollPane(userList);
        leftPanel.setBorder(new TitledBorder("用户列表"));

//        rightPanel2 = new JScrollPane(all_userList);
//        rightPanel2.setBorder(new TitledBorder("全部用户"));

        rightPanel = new JScrollPane(contentArea);
        rightPanel.setBorder(new TitledBorder("消息显示区"));

        centerSplit = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT, leftPanel,
                rightPanel);
        centerSplit.setDividerLocation(150);

//        centerSplit2 = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT, centerSplit,
//                rightPanel2);
//        centerSplit2.setDividerLocation(450);

        northPanel = new JPanel();
        northPanel.setLayout(new GridLayout(1, 6));
        northPanel.add(new JLabel("          人数上限"));
        northPanel.add(txt_max);
        northPanel.add(new JLabel("           端口"));
        northPanel.add(txt_port);
        northPanel.add(btn_start);
        northPanel.add(btn_stop);
        northPanel.setBorder(new TitledBorder("配置信息"));

        frame.setLayout(new BorderLayout());
        frame.add(northPanel, "North");
        frame.add(centerSplit, "Center");
        //frame.add(rightPanel2,BorderLayout.EAST);
        frame.add(southPanel, "South");
        frame.setSize(600, 400);
        //frame.setSize(Toolkit.getDefaultToolkit().getScreenSize());//设置全屏
        int screen_width = Toolkit.getDefaultToolkit().getScreenSize().width;
        int screen_height = Toolkit.getDefaultToolkit().getScreenSize().height;
        frame.setLocation((screen_width - frame.getWidth()) / 2,
                (screen_height - frame.getHeight()) / 2);
        frame.setVisible(true);

        // 关闭窗口时事件
        frame.addWindowListener(new WindowAdapter() {
            public void windowClosing(WindowEvent e) {
                if (isStart) {
                    closeServer();// 关闭服务器
                }
                System.exit(0);// 退出程序
            }
        });

        // 文本框按回车键时事件
        txt_message.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                send();
            }
        });

        // 单击发送按钮时事件
        btn_send.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0) {
                send();
            }
        });

        //单机文件按钮时事件
        btn_send_file.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0) {
                //文件选择对话框启动，当选择了文件以后给每一个client发送文件
                JFileChooser sourceFileChooser = new JFileChooser(".");
                sourceFileChooser.setFileSelectionMode(JFileChooser.FILES_ONLY);
                int status = sourceFileChooser.showOpenDialog(frame);
                File sourceFile = new File(sourceFileChooser.getSelectedFile().getPath());
                //服务器text area提示
                contentArea.append("发送文件：" + sourceFile.getName() + "
");
                for (int i = clients.size() - 1; i >= 0; i--) {
                    SendFileThread sendFile = new SendFileThread(frame, clients.get(i).socket, "服务器", sourceFileChooser, status);
                    sendFile.start();
                    //client端提示
                    clients.get(i).getWriter().println("服务器发送一个文件：" + sourceFile.getName() + "(多人发送)");
                    clients.get(i).getWriter().flush();
                }

            }
        });

        // 单击启动服务器按钮时事件
        btn_start.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {

                if (isStart) {
                    JOptionPane.showMessageDialog(frame, "服务器已处于启动状态，不要重复启动！",
                            "错误", JOptionPane.ERROR_MESSAGE);
                    return;
                }
                int max;//人数
                int port;//端口号
                try {
                    try {
                        max = Integer.parseInt(txt_max.getText());
                    } catch (Exception e1) {
                        throw new Exception("人数上限为正整数！");
                    }
                    if (max <= 0) {
                        throw new Exception("人数上限为正整数！");
                    }
                    try {
                        port = Integer.parseInt(txt_port.getText());
                    } catch (Exception e1) {
                        throw new Exception("端口号为正整数！");
                    }
                    if (port <= 0) {
                        throw new Exception("端口号 为正整数！");
                    }
                    serverStart(max, port);
                    contentArea.append("服务器已成功启动!   人数上限：" + max + ",  端口：" + port
                            + "
");
                    JOptionPane.showMessageDialog(frame, "服务器成功启动!");
                    btn_start.setEnabled(false);
                    txt_max.setEnabled(false);
                    txt_port.setEnabled(false);
                    btn_stop.setEnabled(true);
                    listModel.addElement("全部用户");
                    user_name_update();
                } catch (Exception exc) {
                    JOptionPane.showMessageDialog(frame, exc.getMessage(),
                            "错误", JOptionPane.ERROR_MESSAGE);
                }
            }
        });

        // 单击停止服务器按钮时事件
        btn_stop.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                if (!isStart) {
                    JOptionPane.showMessageDialog(frame, "服务器还未启动，无需停止！", "错误",
                            JOptionPane.ERROR_MESSAGE);
                    return;
                }
                try {
                    closeServer();
                    btn_start.setEnabled(true);
                    txt_max.setEnabled(true);
                    txt_port.setEnabled(true);
                    btn_stop.setEnabled(false);
                    contentArea.append("服务器成功停止!
");
                    JOptionPane.showMessageDialog(frame, "服务器成功停止！");
                } catch (Exception exc) {
                    JOptionPane.showMessageDialog(frame, "停止服务器发生异常！", "错误",
                            JOptionPane.ERROR_MESSAGE);
                }
            }
        });
    }

    /**
     * 监听左边jlist选择的是哪一个用户
     */
    class SelecTry implements ListSelectionListener {
        int change = 0, who;

        public void valueChanged(ListSelectionEvent e) {
            //System.out.println("you selected:"+listModel.getElementAt(userList.getSelectedIndex()));
            sendfor_who = userList.getSelectedIndex();
        }

    }

    /**
     * 找回密码模块
     *
     * @param username
     * @param youxiang
     * @param new_password
     * @return
     */
    public int user_forget(String username, String youxiang, String new_password) {
        try {
            Connection con = null; //定义一个MYSQL链接对象
            Class.forName("com.mysql.jdbc.Driver").newInstance();//MYSQL驱动
            con = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/server_db", "root", "root"); //链接本地MYSQL
            Statement stmt; //创建声明
            stmt = con.createStatement();

            String codingpassword = EncoderByMd5(new_password);

            //查询数据，不能有相同的用户名
            String selectSql = "SELECT * FROM user";
            ResultSet selectRes = stmt.executeQuery(selectSql);
            while (selectRes.next()) { //循环输出结果集
                int userid = selectRes.getInt("Id");
                String username_db = selectRes.getString("username");
                String youxiang_db = selectRes.getString("youxiang");
                if (username.equals(username_db)) {
                    if (youxiang_db.equals(youxiang)) {
                        //更新一条数据
                        String updateSql = "UPDATE user SET password = '" + codingpassword + "' WHERE Id = " + userid + "";
                        long updateRes = stmt.executeUpdate(updateSql);
                        return 1;
                    }

                }
            }
            return 0;
        } catch (Exception e) {
            System.out.print("MYSQL ERROR:" + e.getMessage());
        }
        return 0;
    }


    /**
     * 注册模块
     *
     * @param username
     * @param password
     * @param youxiang
     * @return
     */
    public int user_register(String username, String password, String youxiang) {

        try {
            Connection con = null; //定义一个MYSQL链接对象
            Class.forName("com.mysql.jdbc.Driver").newInstance();//MYSQL驱动
            con = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/server_db", "root", "root"); //链接本地MYSQL
            Statement stmt; //创建声明
            stmt = con.createStatement();

            String codingPassword = EncoderByMd5(password);

            //查询数据，不能有相同的用户名
            String selectSql = "SELECT * FROM user";
            ResultSet selectRes = stmt.executeQuery(selectSql);
            while (selectRes.next()) { //循环输出结果集
                String username_db = selectRes.getString("username");
                if (username.equals(username_db)) {
                    return 2;
                }
            }
            //新增一条数据
            stmt.executeUpdate("INSERT INTO user (username, password,youxiang) VALUES ('" + username + "', '" + codingPassword + "','" + youxiang + "')");
            all_listModel.addElement(username);
            return 1;
        } catch (Exception e) {
            System.out.print("MYSQL ERROR:" + e.getMessage());
        }
        return 0;
    }

    /**
     * 当有用户下线时，在服务器改变状态
     *
     * @param name
     * @return
     */
    public int user_offLine(String name) {
        try {
            Connection con = null; //定义一个MYSQL链接对象
            Class.forName("com.mysql.jdbc.Driver").newInstance();//MYSQL驱动
            con = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/server_db", "root", "root"); //链接本地MYSQL
            Statement stmt; //创建声明
            stmt = con.createStatement();

            //
            String username_fromDb;
            int id = 0;
            String selectSql = "SELECT * FROM user";
            ResultSet selectRes = stmt.executeQuery(selectSql);
            while (selectRes.next()) { //循环输出结果集
                username_fromDb = selectRes.getString("username");
                id = selectRes.getInt("Id");
                if (name.equals(username_fromDb)) {
                    selectSql = "UPDATE user SET state = 0  WHERE Id = " + id + "";
                    stmt.executeUpdate(selectSql);
                    selectSql = "UPDATE user SET serverPort = 0  WHERE Id = " + id + "";
                    stmt.executeUpdate(selectSql);
                    selectSql = "UPDATE user SET ipAdres = ''  WHERE Id = " + id + "";
                    stmt.executeUpdate(selectSql);
                    return 1;
                }
            }
        } catch (Exception e) {
            System.out.print("MYSQL ERROR:" + e.getMessage());
        }
        return 0;
    }

    /**
     * 登陆模块
     *
     * @param username
     * @param password
     * @return
     */
    public int user_login(String username, String password,int serverPort,String myIP) {
        try {
            Connection con = null; //定义一个MYSQL链接对象
            Class.forName("com.mysql.jdbc.Driver").newInstance();//MYSQL驱动
            con = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/server_db", "root", "root"); //链接本地MYSQL
            Statement stmt; //创建声明
            stmt = con.createStatement();


            //
            String username_fromDb;
            String password_fromDb;
            String codingNewPassword;
            int state = 0, id = 0;
            String selectSql = "SELECT * FROM user";
            ResultSet selectRes = stmt.executeQuery(selectSql);
            while (selectRes.next()) { //循环输出结果集
                username_fromDb = selectRes.getString("username");
                password_fromDb = selectRes.getString("password");
                codingNewPassword = EncoderByMd5(password);
                id = selectRes.getInt("Id");
                state = selectRes.getInt("state");
                if (username.equals(username_fromDb) && codingNewPassword.equals(password_fromDb)) {
                    if (state == 0) {
                        selectSql = "UPDATE user SET state = 1  WHERE Id = " + id + "";
                        stmt.executeUpdate(selectSql);
                        selectSql = "UPDATE user SET serverPort = " + serverPort + "  WHERE Id = " + id + "";
                        stmt.executeUpdate(selectSql);
                        selectSql = "UPDATE user SET ipAdres = '" + myIP + "'  WHERE Id = " + id + "";
                        stmt.executeUpdate(selectSql);
                        return 1;//还没有登陆，可以登陆
                    } else {
                        return 2;//已登陆状态，无法登陆
                    }

                }
            }
        } catch (Exception e) {
            System.out.print("MYSQL ERROR:" + e.getMessage());
        }
        return 0;
    }

    /**
     * 启动服务器
     *
     * @param max
     * @param port
     * @throws java.net.BindException
     */
    public void serverStart(int max, int port) throws java.net.BindException {
        try {
            clients = new ArrayList<ClientThread>();
            serverSocket = new ServerSocket(port);
            serverThread = new ServerThread(serverSocket, max);
            serverThread.start();
            isStart = true;
        } catch (BindException e) {
            isStart = false;
            throw new BindException("端口号已被占用，请换一个！");
        } catch (Exception e1) {
            e1.printStackTrace();
            isStart = false;
            throw new BindException("启动服务器异常！");
        }
    }

    /**
     * 关闭服务器
     */
    @SuppressWarnings("deprecation")
    public void closeServer() {
        try {
            if (serverThread != null)
                serverThread.stop();// 停止服务器线程

            for (int i = clients.size() - 1; i >= 0; i--) {
                // 给所有在线用户发送关闭命令
                clients.get(i).getWriter().println("CLOSE");
                clients.get(i).getWriter().flush();
                // 释放资源
                clients.get(i).stop();// 停止此条为客户端服务的线程
                clients.get(i).reader.close();
                clients.get(i).writer.close();
                clients.get(i).socket.close();
                clients.remove(i);
            }
            if (serverSocket != null) {
                serverSocket.close();// 关闭服务器端连接
            }
            listModel.removeAllElements();// 清空用户列表
            isStart = false;
            set_user_state_off();
            user_name_update();
        } catch (IOException e) {
            e.printStackTrace();
            isStart = true;
        }
    }

    /**
     * 群发服务器消息
     *
     * @param message
     * @param who
     */
    public void sendServerMessage(String message, int who) {
        if (who == 0) {
            StringTokenizer stringTokenizer;
            int flag = 0;
            for (int i = all_listModel.size(); i > 0; i--) {
                flag = 0;
                String msg = all_listModel.getElementAt(i - 1) + "";
                stringTokenizer = new StringTokenizer(
                        msg, "---");
                String user_name = stringTokenizer.nextToken();
                for (int j = clients.size() - 1; j >= 0; j--) {
                    if (user_name.equals(clients.get(j).getUser().getName())) {
                        clients.get(j).getWriter().println("服务器对你说   " + message);
                        clients.get(j).getWriter().flush();
                        flag = 1;//该用户在线状态，已发出去
                        break;
                    }
                }
                if (flag == 0) {
                    //用户离线状态，则留言
                    send_messageTo_board("服务器", user_name, message);
                }
            }
            contentArea.append("对  全部用户   发送：" + message + "
");
        } else {
            int flag = 0;
            String msg = "" + all_listModel.getElementAt(who);
            StringTokenizer stringTokenizer = new StringTokenizer(
                    msg, "---");
            String user_name = stringTokenizer.nextToken();
            for (int i = clients.size() - 1; i >= 0; i--) {
                if (user_name.equals(clients.get(i).getUser().getName())) {
                    clients.get(i).getWriter().println("服务器对你说   " + message);
                    clients.get(i).getWriter().flush();
                    flag = 1;//该用户在线状态，已发出去
                    break;
                }
            }
            if (flag == 0) {
//                JOptionPane.showMessageDialog(frame, "该用户不在线，已存为留言板！", "错误",
//                        JOptionPane.ERROR_MESSAGE);
                send_messageTo_board("服务器", user_name, message);
                contentArea.append("对  " + user_name + "  留言：" + message + "
");
            } else {
                contentArea.append("对  " + user_name + "  说：" + message + "
");
            }
        }

    }

    /**
     * 用户不在线时，离线消息保存到服务器里面
     * @param send_from
     * @param send_for
     * @param message
     * @return
     */
    public int send_messageTo_board(String send_from, String send_for, String message) {
        SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");//设置日期格式
        String msg = send_from + "#" + df.format(new Date()) + "#" + message + "#";
        try {
            Connection con = null; //定义一个MYSQL链接对象
            Class.forName("com.mysql.jdbc.Driver").newInstance();//MYSQL驱动
            con = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/server_db", "root", "root"); //链接本地MYSQL
            Statement stmt; //创建声明
            stmt = con.createStatement();

            //查询数据，不能有相同的用户名
            String selectSql = "SELECT * FROM user";
            ResultSet selectRes = stmt.executeQuery(selectSql);
            while (selectRes.next()) { //循环输出结果集
                int Id = selectRes.getInt("Id");
                String username_db = selectRes.getString("username");
                if (send_for.equals(username_db)) {
                    String old_message = selectRes.getString("message");
                    String updateSql = "UPDATE user SET message = '" + old_message + msg + "' WHERE Id = " + Id + "";
                    stmt.executeUpdate(updateSql);
                    return 1;
                }
            }
            return 0;
        } catch (Exception e) {
            System.out.print("MYSQL ERROR:" + e.getMessage());
        }
        return 0;
    }

    /**
     * 服务器线程
     */
    class ServerThread extends Thread {
        private ServerSocket serverSocket;
        private int max;// 人数上限

        // 服务器线程的构造方法
        public ServerThread(ServerSocket serverSocket, int max) {
            this.serverSocket = serverSocket;
            this.max = max;
        }

        public void run() {
            while (true) {// 不停的等待客户端的链接
                try {
                    Socket socket = serverSocket.accept();
                    if (clients.size() == max) {// 如果已达人数上限
                        BufferedReader r = new BufferedReader(
                                new InputStreamReader(socket.getInputStream()));
                        PrintWriter w = new PrintWriter(socket
                                .getOutputStream());
                        // 接收客户端的基本用户信息
                        String inf = r.readLine();
                        StringTokenizer st = new StringTokenizer(inf, "#");
                        User user = new User(st.nextToken(), st.nextToken());
                        // 反馈连接成功信息
                        w.println("MAX#服务器：对不起，" + user.getName()
                                + user.getIp() + "，服务器在线人数已达上限，请稍后尝试连接！");
                        w.flush();
                        // 释放资源
                        r.close();
                        w.close();
                        socket.close();
                        continue;
                    }
                    ClientThread client = new ClientThread(socket);
                    client.start();// 开启对此客户端服务的线程
                    client.getUser().setState(1);//在线状态
                    clients.add(client);
                    listModel.addElement(client.getUser().getName());// 更新在线列表
                    contentArea.append(client.getUser().getName()
                            + client.getUser().getIp() + "上线!
");
//                    user_name_update();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

    /**
     * 为一个客户端服务的线程
     */
    class ClientThread extends Thread {
        private Socket socket;
        private BufferedReader reader;
        private PrintWriter writer;
        private User user;

        public BufferedReader getReader() {
            return reader;
        }

        public PrintWriter getWriter() {
            return writer;
        }

        public User getUser() {
            return user;
        }

        // 客户端线程的构造方法
        public ClientThread(Socket socket) {
            try {
                this.socket = socket;
                reader = new BufferedReader(new InputStreamReader(socket
                        .getInputStream()));
                writer = new PrintWriter(socket.getOutputStream());
                // 接收客户端的基本用户信息
                String inf = reader.readLine();
                StringTokenizer st = new StringTokenizer(inf, "#");
                user = new User(st.nextToken(), st.nextToken());
                // 反馈连接成功信息
                writer.println(user.getName() + user.getIp() + "与服务器连接成功!");
                writer.flush();


            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        @SuppressWarnings("deprecation")
        public void run() {// 不断接收客户端的消息，进行处理。
            String message = null;
            while (true) {
                try {
                    message = reader.readLine();// 接收客户端消息
                    StringTokenizer stringTokenizer = new StringTokenizer(
                            message, "#");
                    String command = stringTokenizer.nextToken();// 命令
                    if (command.equals("CLOSE"))// 下线命令
                    {
                        contentArea.append(this.getUser().getName()
                                + this.getUser().getIp() + "下线!
");
                        // 断开连接释放资源
                        user_offLine(this.getUser().getName());
                        this.getUser().setState(0);
                        reader.close();
                        writer.close();
                        socket.close();

                        user_name_update();//更新用户状态


                        //反馈用户状态
                        String liststr = "";
                        for (int j = 1; j < all_listModel.size(); j++) {
                            liststr += all_listModel.get(j) + "#";
                        }
                        // 向所有在线用户发送该用户上线命令
                        for (int j = clients.size()-1 ; j >= 0; j--) {
                            clients.get(j).getWriter().println(
                                    "USERLIST#" + all_listModel.size() + "#" + liststr);
                            clients.get(j).getWriter().flush();
                        }
                        //user_name_update();//更新用户状态

                        listModel.removeElement(user.getName());// 更新在线列表

                        // 删除此条客户端服务线程
                        for (int i = clients.size() - 1; i >= 0; i--) {
                            if (clients.get(i).getUser() == user) {
                                ClientThread temp = clients.get(i);
                                clients.remove(i);// 删除此用户的服务线程
                                temp.stop();// 停止这条服务线程
                                return;
                            }
                        }
                    } else if (command.equals("USERLOGIN")) {
                        String username = stringTokenizer.nextToken();
                        String password = stringTokenizer.nextToken();
                        int serverPort = Integer.parseInt(stringTokenizer.nextToken());
                        String myIP = stringTokenizer.nextToken();
                        int i = user_login(username, password,serverPort,myIP);
                        if (1 == i) {
                            user_name_update();
                            String msg = get_message(username);
                            if (msg.equals("")) {
                                writer.println("USERLOGIN#OK#");
                                writer.flush();
                            } else {
                                writer.println("USERLOGIN#OK#" + msg);
                                writer.flush();
                            }


                            //反馈用户状态
                            String temp = "";
                            for (int j = 1; j < all_listModel.size(); j++) {
                                temp += all_listModel.get(j) + "#";
                            }
                            // 向所有在线用户发送该用户上线命令
                            for (int j = clients.size()-1 ; j >= 0; j--) {
                                clients.get(j).getWriter().println(
                                        "USERLIST#" + all_listModel.size() + "#" + temp);
                                clients.get(j).getWriter().flush();
                            }

                        } else if (2 == i) {
                            writer.println("USERLOGIN#ALREADY");
                            writer.flush();
                        } else {
                            writer.println("USERLOGIN#NO");
                            writer.flush();

                        }
                        //user_name_update();
                    } else if (command.equals("USERZHUCE")) {
                        String username = stringTokenizer.nextToken();
                        String password = stringTokenizer.nextToken();
                        String youxiang = stringTokenizer.nextToken();
                        int i = user_register(username, password, youxiang);
                        if (1 == i) {
                            writer.println("USERZHUCE#OK");
                            writer.flush();
                            contentArea.append("有新用户注册！     用户名：" + username + "
");
                            user_name_update();//更新用户状态
                        } else if (i == 2) {
                            writer.println("USERZHUCE#exict");
                            writer.flush();
                        } else {
                            writer.println("USERZHUCE#NO");
                            writer.flush();
                        }
                    } else if (command.equals("USERFORGET")) {
                        String username = stringTokenizer.nextToken();
                        String youxiang = stringTokenizer.nextToken();
                        String new_password = stringTokenizer.nextToken();
                        int i = user_forget(username, youxiang, new_password);
                        if (1 == i) {
                            //JOptionPane.showMessageDialog(frame, "登陆成功!" );
                            writer.println("USERFORGET#OK");
                            writer.flush();
                            contentArea.append("   用户：" + username + "  修改密码！
");
                        } else if (i == 2) {
                            writer.println("USERFORGET#YOUXIANG_WRONG");
                            writer.flush();
                        } else if (i == 3) {
                            writer.println("USERFORGET#NAME_NO_exict");
                            writer.flush();
                        } else {
                            writer.println("USERFORGET#NO");
                            writer.flush();
                        }
                    } else if (command.equals("P2P")) {
                        String username = stringTokenizer.nextToken();
                        int i = get_user_serverPort(username);
                        String ip = get_user_serverIP(username);
                        if(i!=0){
                            writer.println("P2P#OK#"+username+"#"+i+"#"+ip);
                            writer.flush();
                        }else{
                            writer.println("P2P#NO#"+username);
                            writer.flush();
                        }
                    }else if(command.equals("LIXIAN")){
                        String username_sent = stringTokenizer.nextToken();
                        String username_receive = stringTokenizer.nextToken();
                        String msg = stringTokenizer.nextToken();
                        send_messageTo_board(username_sent,username_receive,msg);
                        System.out.println("离线发送ok");
                    } else {
                        dispatcherMessage(message);// 转发消息
                    }
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }

        public int get_user_serverPort(String user_name){
            try {
                Connection con = null; //定义一个MYSQL链接对象
                Class.forName("com.mysql.jdbc.Driver").newInstance();//MYSQL驱动
                con = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/server_db", "root", "root"); //链接本地MYSQL
                Statement stmt; //创建声明
                stmt = con.createStatement();

                //查询数据，不能有相同的用户名
                String selectSql = "SELECT * FROM user";
                ResultSet selectRes = stmt.executeQuery(selectSql);
                while (selectRes.next()) { //循环输出结果集
                    String username_db = selectRes.getString("username");
                    if (user_name.equals(username_db)) {
                        int serverPort = selectRes.getInt("serverPort");
                        return serverPort;
                    }
                }
            } catch (Exception e) {
                System.out.print("MYSQL ERROR:" + e.getMessage());
            }
            return 0;
        }

        public String get_user_serverIP(String user_name){
            try {
                Connection con = null; //定义一个MYSQL链接对象
                Class.forName("com.mysql.jdbc.Driver").newInstance();//MYSQL驱动
                con = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/server_db", "root", "root"); //链接本地MYSQL
                Statement stmt; //创建声明
                stmt = con.createStatement();

                //查询数据，不能有相同的用户名
                String selectSql = "SELECT * FROM user";
                ResultSet selectRes = stmt.executeQuery(selectSql);
                while (selectRes.next()) { //循环输出结果集
                    String username_db = selectRes.getString("username");
                    if (user_name.equals(username_db)) {
                        String serverIP = selectRes.getString("ipAdres");
                        return serverIP;
                    }
                }
            } catch (Exception e) {
                System.out.print("MYSQL ERROR:" + e.getMessage());
            }
            return "";
        }

        public String get_message(String name) {
            try {
                Connection con = null; //定义一个MYSQL链接对象
                Class.forName("com.mysql.jdbc.Driver").newInstance();//MYSQL驱动
                con = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/server_db", "root", "root"); //链接本地MYSQL
                Statement stmt; //创建声明
                stmt = con.createStatement();

                //查询数据，不能有相同的用户名
                String selectSql = "SELECT * FROM user";
                ResultSet selectRes = stmt.executeQuery(selectSql);
                while (selectRes.next()) { //循环输出结果集
                    int Id = selectRes.getInt("Id");
                    String username_db = selectRes.getString("username");
                    if (name.equals(username_db)) {
                        String message = selectRes.getString("message");
                        String updateSql = "UPDATE user SET message = '' WHERE Id = " + Id + "";
                        stmt.executeUpdate(updateSql);
                        return message;
                    }
                }
                return "";
            } catch (Exception e) {
                System.out.print("MYSQL ERROR:" + e.getMessage());
            }
            return "";
        }

        // 转发消息
        public void dispatcherMessage(String message) {
            StringTokenizer stringTokenizer = new StringTokenizer(message, "#");
            String source = stringTokenizer.nextToken();
            String owner = stringTokenizer.nextToken();
            String content = stringTokenizer.nextToken();

            if (owner.equals("ALL")) {// 群发
                message = source + "说：" + content;
                contentArea.append(message + "
");
                for (int i = clients.size() - 1; i >= 0; i--) {
                    clients.get(i).getWriter().println(message + "(多人发送)");
                    clients.get(i).getWriter().flush();
                }
            } else {
                for (int i = clients.size() - 1; i >= 0; i--) {
                    if (clients.get(i).user.getName().equals(owner)) {
                        clients.get(i).getWriter().println(owner + "  对你说: " + content);
                        clients.get(i).getWriter().flush();
                        //contentArea.append(owner+"  对    "+ clients.get(i).user.getName()+ "  说  :"+ content+"
");
                    }
                    if (clients.get(i).user.getName().equals(source)) {
                        clients.get(i).getWriter().println("对   " + source + "  说: " + content);
                        clients.get(i).getWriter().flush();
                    }
                }
            }
        }
    }
}

import java.io.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;

import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.ProgressMonitor;
import javax.swing.ProgressMonitorInputStream;


public class SendFileThread extends Thread {
    private Socket clientSocket;
    private String name;
    JFileChooser sourceFileChooser;
    int status;
    JFrame JFrame;

    public SendFileThread(JFrame frame, Socket socket, String name, JFileChooser sourceFileChooser, int status) {
        this.clientSocket = socket;
        this.name = name;
        this.sourceFileChooser = sourceFileChooser;
        this.status = status;
        this.JFrame = frame;
    }

    public void run() {
//        JFileChooser sourceFileChooser = new JFileChooser(".");
//        sourceFileChooser.setFileSelectionMode(JFileChooser.FILES_ONLY);
//        int status = sourceFileChooser.showOpenDialog(null);
        if (status == JFileChooser.APPROVE_OPTION) {
            File sourceFile = new File(sourceFileChooser.getSelectedFile().getPath());
            String sourceFilePath = sourceFile.getAbsolutePath();
            String fileName = sourceFile.getName();
            //System.out.println(sourceFilePath+"\"+fileName);
            try {
                PrintWriter sendToClient = new PrintWriter(clientSocket.getOutputStream());
                BufferedReader getFromClient = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
                ServerSocket fileSenderSocket = null;
                try {
                    fileSenderSocket = new ServerSocket(0);
                } catch (IOException ex1) {
                    JOptionPane.showMessageDialog(JFrame, "无法分配端口以发送此文件!", "错误", JOptionPane.ERROR_MESSAGE);
                }
                sendToClient.println("FILE#" + fileSenderSocket.getLocalPort() + "#" + fileName + "#"
                        + String.valueOf(sourceFile.length()) + "#" + clientSocket.getInetAddress().getHostAddress() + "#" + name);
                sendToClient.flush();
                //System.out.println("Sender: "+fileSenderSocket.getLocalSocketAddress());
                Socket fileReceiverSocket = fileSenderSocket.accept();

                BufferedReader getFromReceiver = null;
                PrintWriter sendToReceiver = null;
                try {
                    getFromReceiver = new BufferedReader(new InputStreamReader(fileReceiverSocket.getInputStream()));
                    sendToReceiver = new PrintWriter(fileReceiverSocket.getOutputStream());
                } catch (IOException ex) {
                } finally {
                }
                String judge = getFromReceiver.readLine();
                if (judge.equals("accepted")) {
                    DataOutputStream sendFileToReceiver = new DataOutputStream(new BufferedOutputStream(fileReceiverSocket.getOutputStream()));
                    ProgressMonitorInputStream monitor;
                    FileInputStream sendFileStream = null;
                    try {
                        sendFileStream = new FileInputStream(sourceFile);
                    } catch (FileNotFoundException ex) {
                        sendToReceiver.flush();
                        sendFileToReceiver.writeByte(0);
                        sendFileToReceiver.flush();
                        return;
                    }
                    monitor = new ProgressMonitorInputStream(JFrame, "正在发送： " + fileName, sendFileStream);
                    ProgressMonitor progressMonitor = monitor.getProgressMonitor();

                    int read_unit = 500;
                    long fileSize = monitor.available();
                    int readed = 0;
                    byte[] data = new byte[read_unit];
                    try {
                        sendFileToReceiver.writeByte(1);
                        sendFileToReceiver.flush();
                        while (monitor.available() > 0) {
                            int in = monitor.read(data);
                            readed += in;
                            float process = (float) readed / fileSize * 100;
                            progressMonitor.setNote(process + " % 完成");
                            if (in > 0) {
                                sendFileToReceiver.write(data, 0, in);
                            }
                        }
                        sendFileToReceiver.flush();
                    } catch (IOException e) {
                        JOptionPane.showMessageDialog(JFrame, "传输中断!", "错误", JOptionPane.ERROR_MESSAGE);
                    } finally {
                        if (sendFileStream != null)
                            try {
                                sendFileStream.close();
                                monitor.close();
                            } catch (IOException e) {
                            }
                    }
                    try {
                        fileReceiverSocket.close();
                    } catch (IOException ex1) {
                    }
                } else if (judge.equals("refused")) {
                    JOptionPane.showMessageDialog(JFrame, "对方拒绝接受文件 " + fileName, "错误！", JOptionPane.INFORMATION_MESSAGE);
                }

            } catch (IOException ex) {
            } finally {
            }
        }
    }
}

//用户信息类
public class User{
    private String name;
    private String ip;
    private int state;

    public User(String name, String ip) {
        this.name = name;
        this.ip = ip;
        state = 0;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getIp() {
        return ip;
    }

    public void setIp(String ip) {
        this.ip = ip;
    }

    public int getState() {
        return state;
    }

    public void setState(int state) {
        this.state = state;
    }
}

数据库：

是通过MD5加密保存。

客户端代码：

package com.company;

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Font;
import java.awt.GridLayout;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.io.*;
import java.net.BindException;
import java.net.InetAddress;
import java.net.ServerSocket;
import java.net.Socket;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;
import java.util.StringTokenizer;

import javax.swing.*;
import javax.swing.border.TitledBorder;
import javax.swing.event.ListSelectionEvent;
import javax.swing.event.ListSelectionListener;

//import socket_chat_server.Server.ClientThread;
//import socket_chat_server.Server.SelecTry;

public class Client{

    private JPanel sendPanel;
    private JButton btn_send_file;
    private JFrame frame;
    private JList userList;
    private JTextArea textArea;
    private JTextField textField;
    private JTextField txt_port;
    private JTextField txt_hostIp;
    private JTextField txt_name;
    private JButton btn_start;
    private JButton btn_stop;
    private JButton btn_send;
    private JPanel northPanel;
    private JPanel southPanel;
    private JScrollPane rightScroll;
    private JScrollPane leftScroll;
    private JSplitPane centerSplit;

    private JPanel logPanle;
    private JFrame loginframe;
    private JLabel label_username;
    private JLabel label_password;
    private JTextField txt_login_name;
    private JTextField txt_password;
    private JTextField txt_login_ip;
    private JTextField txt_login_port;
    private JTextField txt_login_forget;
    private JButton btn_submit;
    private JButton btn_zhuce;
    private JButton btn_forget_pass;

    private DefaultListModel listModel;
    private boolean isConnected = false;

    private int sendfor_who;
    private int server_port=0;

    private ServerSocket serverSocket;
    private ServerThread serverThread;
    private Socket socketfor_p2p;
    private boolean isConnected_p2p = false;
    private ArrayList<ClientThread> clients;//客户线程数组
    private PrintWriter P2P_printWriter;//点对点服务的输出流
    private BufferedReader P2P_bufferReader;//点对点服务的输入流
    private MessageThread_P2P messageThread_for_p2p;// 负责接收p2p消息的线程
    private Map<String, Boolean> P2P_connected_user = new HashMap<String, Boolean>();

    private Socket socket;
    private PrintWriter writer;
    private BufferedReader reader;
    private MessageThread messageThread;// 负责接收消息的线程
    private Map<String, User> onLineUsers = new HashMap<String, User>();// 所有在线用户
    private String myIP = "";//每一个客户端都有唯一的IP地址

    // 主方法,程序入口
    public static void main(String[] args) throws BindException {
        new Client();

    }

    class SelecTry implements ListSelectionListener
    {
        int change=0,who;
        public void valueChanged(ListSelectionEvent e){
            //System.out.println("you selected:"+listModel.getElementAt(userList.getSelectedIndex()));
            sendfor_who=userList.getSelectedIndex();
            isConnected_p2p = false;
        }

    }

    /**
     * 连接服务器
     *
     * @param port
     * @param hostIp
     * @param name
     */
    public boolean connectServer_p2p(int port, String hostIp, String name) {
        // 连接服务器
        try {
            socketfor_p2p = new Socket(hostIp, port);// 根据端口号和服务器ip建立连接
            P2P_printWriter = new PrintWriter(socketfor_p2p.getOutputStream());
            P2P_bufferReader = new BufferedReader(new InputStreamReader(socketfor_p2p
                    .getInputStream()));

            messageThread_for_p2p = new MessageThread_P2P(P2P_bufferReader);
            messageThread_for_p2p.start();
            P2P_connected_user.put(name,true);
            isConnected_p2p = true;// 已经连接上了
            return true;
        } catch (Exception e) {
            textArea.append("与端口号为：" + port + "    IP地址为：" + hostIp
                    + "   的服务连接失败!" + "
");
            isConnected_p2p = false;// 未连接上
            return false;
        }
    }

    /**
     * 关闭服务
     */
    @SuppressWarnings("deprecation")
    public void closeServer() {
        try {
            if (serverThread != null)
                serverThread.stop();// 停止服务器线程

            for (int i = clients.size() - 1; i >= 0; i--) {
                // 给所有在线用户发送关闭命令
                clients.get(i).getWriter().println("CLOSE#"+frame.getTitle());
                clients.get(i).getWriter().flush();
                // 释放资源
                clients.get(i).stop();// 停止此条为客户端服务的线程
                clients.get(i).reader_ptp.close();
                clients.get(i).writer_ptp.close();
                clients.get(i).socket.close();
                clients.remove(i);
            }
            if (serverSocket != null) {
                serverSocket.close();// 关闭服务器端连接
            }
            listModel.removeAllElements();// 清空用户列表
//            isStart = false;
        } catch (IOException e) {
            e.printStackTrace();
//            isStart = true;
        }
    }

    // 不断接收消息的线程
    class MessageThread_P2P extends Thread {
        private BufferedReader reader_ptp;

        // 接收消息线程的构造方法
        public MessageThread_P2P(BufferedReader reader) {
            this.reader_ptp = reader;

        }

        // 被动的关闭连接
        public synchronized void closeCon() throws Exception {
            System.out.println("close :*************");
            // 被动的关闭连接释放资源
            if (reader_ptp != null) {
                reader_ptp.close();
            }
            if (P2P_printWriter != null) {
                P2P_printWriter.close();
            }
            if (socketfor_p2p != null) {
                socketfor_p2p.close();
            }
            isConnected_p2p = false;// 修改状态为断开

        }

        public void run() {
            String message = "";
            while (true) {
                try {
                    message = reader_ptp.readLine();
                    StringTokenizer stringTokenizer = new StringTokenizer(
                            message, "/#");
                    String command = stringTokenizer.nextToken();// 命令
                    if (command.equals("CLOSE"))// 服务器已关闭命令
                    {
                        String user = stringTokenizer.nextToken();
                        textArea.append("用户 "+user+"  已下线，p2p服务已关闭!
");
                        closeCon();// 被动的关闭连接
                        JOptionPane.showMessageDialog(frame, "用户 "+user+"  已下线，p2p服务已关闭!", "错误",
                                JOptionPane.ERROR_MESSAGE);
                        return;// 结束线程
                    } else if (command.equals("FILE")) {
                        int portNumber = Integer.parseInt(stringTokenizer.nextToken());
                        String fileName = stringTokenizer.nextToken();
                        long fileSize = Long.parseLong(stringTokenizer.nextToken());
                        String ip = stringTokenizer.nextToken();
                        String Nickname = stringTokenizer.nextToken();
                        ReceiveFileThread receiveFile = new ReceiveFileThread(textArea,frame,ip, portNumber, fileName, fileSize, Nickname);
                        receiveFile.start();
                        textArea.append("从 "+Nickname+" 接受文件:"+fileName+",大小为:"+fileSize
                                +"ip:"+ip+"port:"+portNumber+"
");
                    } else {// 普通消息
                        textArea.append(""+message + "
");
                    }
                } catch (IOException e) {
                    e.printStackTrace();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }
    }

    /**
     * 启动服务器
     *
     * @param port
     * @throws java.net.BindException
     */
    public void serverStart(int port) throws java.net.BindException {
        try {
            clients = new ArrayList<ClientThread>();
            serverSocket = new ServerSocket(port);
            serverThread = new ServerThread(serverSocket);
            serverThread.start();
            server_port = serverSocket.getLocalPort();
            InetAddress addr = InetAddress.getLocalHost();
            myIP = addr.getHostAddress();//获得本机IP
//            myIP = serverSocket.getInetAddress().getHostAddress();
            System.out.println("mmyIP=="+myIP+"
");
        } catch (BindException e) {
            throw new BindException("端口号已被占用，请换一个！");
        } catch (Exception e1) {
            e1.printStackTrace();
            throw new BindException("启动服务器异常！");
        }
    }

    /**
     * 为另一个主动链接的客户端提供服务的线程
     */
    class ClientThread extends Thread {
        private Socket socket;
        private BufferedReader reader_ptp;
        private PrintWriter writer_ptp;
        private User user;

        public BufferedReader getReader() {
            return reader_ptp;
        }

        public PrintWriter getWriter() {
            return writer_ptp;
        }

        public User getUser() {
            return user;
        }

        // 客户端线程的构造方法
        public ClientThread(Socket socket) {
            try {
                this.socket = socket;
                reader_ptp = new BufferedReader(new InputStreamReader(socket
                        .getInputStream()));
                writer_ptp = new PrintWriter(socket.getOutputStream());

                // 接收客户端的基本用户信息
                String inf = reader_ptp.readLine();
                StringTokenizer st = new StringTokenizer(inf, "#");
                user = new User(st.nextToken(), socket.getLocalAddress().toString());
                // 反馈连接成功信息
                writer_ptp.println(frame.getTitle()+"  对你说：  "+user.getName()+"/"+user.getIp()+"你好！"+"与我"+frame.getTitle()+"建立链接成功！");
                writer_ptp.flush();
//                // 反馈当前在线用户信息
//                if (clients.size() > 0) {
//                    String temp = "";
//                    for (int i = clients.size() - 1; i >= 0; i--) {
//                        temp += (clients.get(i).getUser().getName() + "/" + clients
//                                .get(i).getUser().getIp())
//                                + "#";
//                    }
//                    writer.println("USERLIST#" + clients.size() + "#" + temp);
//                    writer.flush();
//                }
//                // 向所有在线用户发送该用户上线命令
//                for (int i = clients.size() - 1; i >= 0; i--) {
//                    clients.get(i).getWriter().println(
//                            "ADD#" + user.getName() + user.getIp());
//                    clients.get(i).getWriter().flush();
//                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        @SuppressWarnings("deprecation")
        public void run() {// 不断接收客户端的消息，进行处理。
            String message = null;
            while (true) {
                try {
                    message = reader_ptp.readLine();// 接收客户端消息
                    StringTokenizer stringTokenizer = new StringTokenizer(message,"/#");
                    String command = stringTokenizer.nextToken();
                    if (command.equals("CLOSE"))// 下线命令
                    {
                        textArea.append("与"+this.getUser().getName()
                                + this.getUser().getIp() + "建立连接成功!
");
                        // 断开连接释放资源
                        this.getUser().setState(0);
                        reader.close();
                        writer.close();
                        socket.close();

                    } else if (command.equals("FILE")) {
                        int portNumber = Integer.parseInt(stringTokenizer.nextToken());
                        String fileName = stringTokenizer.nextToken();
                        long fileSize = Long.parseLong(stringTokenizer.nextToken());
                        String ip = stringTokenizer.nextToken();
                        String Nickname = stringTokenizer.nextToken();
                        ReceiveFileThread receiveFile = new ReceiveFileThread(textArea,frame,ip, portNumber, fileName, fileSize, Nickname);
                        receiveFile.start();
                        textArea.append("从 "+Nickname+" 接受文件 :"+fileName+",大小为:  "+fileSize
                                +"   ip: "+ip+"    port:"+portNumber+"
");
                    }else {
                        textArea.append(user.getName()+"  对你说： "+message+"
");
                    }
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }

    }

    /**
     * 服务线程
     */
    class ServerThread extends Thread {
        private ServerSocket serverSocket;

        // 服务器线程的构造方法
        public ServerThread(ServerSocket serverSocket) {
            this.serverSocket = serverSocket;
        }

        public void run() {
            while (true) {// 不停的等待客户端的链接
                try {
                    Socket socket = serverSocket.accept();
                    ClientThread client = new ClientThread(socket);
                    client.start();// 开启对此客户端服务的线程
                    clients.add(client);
                    textArea.append("有新用户p2p链接
");
//                    user_name_update();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }


    public void sendFile() {
        //文件选择对话框启动，当选择了文件以后给每一个client发送文件
        JFileChooser sourceFileChooser = new JFileChooser(".");
        sourceFileChooser.setFileSelectionMode(JFileChooser.FILES_ONLY);
        int status = sourceFileChooser.showOpenDialog(frame);
        File sourceFile = new File(sourceFileChooser.getSelectedFile().getPath());
        //服务器text area提示
        textArea.append("发送文件：" + sourceFile.getName() + "
");

        if(sendfor_who==0){
            textArea.append("对服务器发送文件!");
        }else{
            StringTokenizer st = new StringTokenizer(listModel.getElementAt(sendfor_who)+"", "---()");
            String user_name = st.nextToken();
            String user_state = st.nextToken();
            if (user_state.equals("在线")) {
                for (int i = clients.size()-1; i >= 0; i--) {
                    if (clients.get(i).getUser().getName().equals(user_name)) {
                        SendFileThread sendFile = new SendFileThread(frame, clients.get(i).socket, frame.getTitle(), sourceFileChooser, status);
                        sendFile.start();
                        //client端提示
                        textArea.append("给  "+user_name+"  发送一个文件：" + sourceFile.getName() + "
");
                        return;
                    }
                }
                SendFileThread sendFile = new SendFileThread(frame, socketfor_p2p, frame.getTitle(), sourceFileChooser, status);
                sendFile.start();
                //client端提示
                textArea.append("给  "+user_name+"  发送一个文件：" + sourceFile.getName() + "
");
            }else{
                JOptionPane.showMessageDialog(frame, "用户不在线，不能发送文件！");
            }
        }

    }



    // 执行发送
    public void send() {
        if (!isConnected) {
            JOptionPane.showMessageDialog(frame, "还没有连接服务器，无法发送消息！", "错误",
                    JOptionPane.ERROR_MESSAGE);
            return;
        }
        String message = textField.getText().trim();
        if (message == null || message.equals("")) {
            JOptionPane.showMessageDialog(frame, "消息不能为空！", "错误",
                    JOptionPane.ERROR_MESSAGE);
            return;
        }
        //sendMessage(frame.getTitle() + "#" + "ALL" + "#" + message);
        if(sendfor_who==0){
            sendMessage(frame.getTitle() + "#" + "ALL" + "#" + message);
            textField.setText(null);
        }else{
            StringTokenizer st = new StringTokenizer(listModel.getElementAt(sendfor_who)+"", "---()");
            String user_name = st.nextToken();
            String user_state = st.nextToken();
            if (user_state.equals("在线")) {
                for (int i = clients.size()-1; i >= 0; i--) {
                    if (clients.get(i).getUser().getName().equals(user_name)) {
                        clients.get(i).writer_ptp.println("对 "+user_name+"  说：  "+message+"
");
                        clients.get(i).writer_ptp.flush();
                        textArea.append("对  "+user_name+"  说： "+message+"
");
                        textField.setText(null);
                        return;
                    }
                }
                if (!isConnected_p2p) {
                    JOptionPane.showMessageDialog(frame, "点对点即将连接！");
                    sendMessage("P2P#"+user_name);
                }else{
                    P2P_printWriter.println(message);
                    P2P_printWriter.flush();
                    textArea.append("对  "+user_name+"  说： "+message+"
");
                    textField.setText(null);
                }

            }else{
                JOptionPane.showMessageDialog(frame, "用户不在线，已存为留言！");
                sendMessage("LIXIAN#"+frame.getTitle() + "#" + user_name + "#" + message);
                textArea.append("对  "+user_name+"  留言： "+message+"
");
                textField.setText(null);
            }
        }
    }

    public void Login(){
        Font font = new Font("宋体", 1, 16);

        logPanle = new JPanel();
        //logPanle.setLayout(new GridLayout(2, 2));
        logPanle.setBounds(2, 45, 250, 225);
        logPanle.setBackground(Color.lightGray);
        logPanle.setLayout(new GridLayout(5, 2, 20, 20));

        label_username = new JLabel("用户名:");
        label_username.setFont(font);
        label_username.setHorizontalAlignment(SwingConstants.CENTER);
        logPanle.add(label_username);

        txt_login_name = new JTextField("name");
        txt_login_name.setFont(font);
        logPanle.add(txt_login_name);

        label_password = new JLabel("密 码:");
        label_password.setFont(font);
        label_password.setHorizontalAlignment(SwingConstants.CENTER);
        logPanle.add(label_password);

        txt_password = new JTextField("");
        txt_password.setFont(font);
        logPanle.add(txt_password);

        txt_login_ip = new JTextField("127.0.0.1");
        txt_login_ip.setFont(font);
        logPanle.add(txt_login_ip);

        txt_login_port = new JTextField("6666");
        txt_login_port.setFont(font);
        logPanle.add(txt_login_port);

        logPanle.add(txt_login_ip);
        logPanle.add(txt_login_port);

        btn_submit = new JButton("登陆");
        btn_submit.setFont(font);
        btn_submit.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                int port;
                String message_name = txt_login_name.getText().trim();
                if (message_name == null || message_name.equals("")) {
                    JOptionPane.showMessageDialog(logPanle, "用户名不能为空！", "错误",
                            JOptionPane.ERROR_MESSAGE);
                    return;
                }
                String message_pw = txt_password.getText().trim();
                if (message_pw == null || message_pw.equals("")) {
                    JOptionPane.showMessageDialog(logPanle, "密码不能为空！", "错误",
                            JOptionPane.ERROR_MESSAGE);
                    return;
                }
                if (isConnected) {
                    String message1 = txt_login_name.getText().trim();
                    if (message1 == null || message1.equals("")) {
                        JOptionPane.showMessageDialog(logPanle, "用户名不能为空！", "错误",
                                JOptionPane.ERROR_MESSAGE);
                        return;
                    }
                    String message2 = txt_password.getText().trim();
                    if (message2 == null || message2.equals("")) {
                        JOptionPane.showMessageDialog(logPanle, "密码不能为空！", "错误",
                                JOptionPane.ERROR_MESSAGE);
                        return;
                    }
                    sendMessage("USERLOGIN#"+message1+"#"+message2+"#"+server_port+"#"+myIP);
                    return;
                }else{
                    try {
                        try {
                            port = Integer.parseInt(txt_login_port.getText().trim());
                        } catch (NumberFormatException e2) {
                            throw new Exception("端口号不符合要求!端口为整数!");
                        }
                        String hostIp = txt_login_ip.getText().trim();
                        String name = txt_login_name.getText().trim();
                        if (name.equals("") || hostIp.equals("")) {
                            throw new Exception("姓名、服务器IP不能为空!");
                        }
                        boolean flag = connectServer(port, hostIp, name);
                        if (flag == false) {
                            throw new Exception("与服务器连接失败!");
                        }
                        frame.setTitle(name);
                        listModel.addElement("全部用户");
                    } catch (Exception exc) {
                        JOptionPane.showMessageDialog(loginframe, exc.getMessage(),
                                "错误", JOptionPane.ERROR_MESSAGE);
                        return;
                    }
                }

                sendMessage("USERLOGIN#"+message_name+"#"+message_pw+"#"+server_port+"#"+myIP);
            }
        });
        logPanle.add(btn_submit);

        btn_zhuce = new JButton("注册");
        btn_zhuce.setFont(font);
        btn_zhuce.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                int port;
                String message_name = txt_login_name.getText().trim();
                if (message_name == null || message_name.equals("")) {
                    JOptionPane.showMessageDialog(logPanle, "用户名不能为空！", "错误",
                            JOptionPane.ERROR_MESSAGE);
                    return;
                }
                String message_pw = txt_password.getText().trim();
                if (message_pw == null || message_pw.equals("")) {
                    JOptionPane.showMessageDialog(logPanle, "密码不能为空！", "错误",
                            JOptionPane.ERROR_MESSAGE);
                    return;
                }
                String message_yx = txt_login_forget.getText().trim();
                if (message_yx == null || message_yx.equals("")) {
                    JOptionPane.showMessageDialog(logPanle, "注册邮箱不能为空！", "错误",
                            JOptionPane.ERROR_MESSAGE);
                    return;
                }

                if (isConnected) {
                    String message1 = txt_login_name.getText().trim();
                    if (message1 == null || message1.equals("")) {
                        JOptionPane.showMessageDialog(logPanle, "用户名不能为空！", "错误",
                                JOptionPane.ERROR_MESSAGE);
                        return;
                    }
                    String message2 = txt_password.getText().trim();
                    if (message2 == null || message2.equals("")) {
                        JOptionPane.showMessageDialog(logPanle, "密码不能为空！", "错误",
                                JOptionPane.ERROR_MESSAGE);
                        return;
                    }
                    String message3 = txt_login_forget.getText().trim();
                    if (message3 == null || message3.equals("")) {
                        JOptionPane.showMessageDialog(logPanle, "注册邮箱不能为空！", "错误",
                                JOptionPane.ERROR_MESSAGE);
                        return;
                    }
                    sendMessage("USERZHUCE#"+message1+"#"+message2+"#"+message3);
                    return;
                }else{
                    try {
                        try {
                            port = Integer.parseInt(txt_login_port.getText().trim());
                        } catch (NumberFormatException e2) {
                            throw new Exception("端口号不符合要求!端口为整数!");
                        }
                        String hostIp = txt_login_ip.getText().trim();
                        String name = txt_login_name.getText().trim();
                        if (name.equals("") || hostIp.equals("")) {
                            throw new Exception("姓名、服务器IP不能为空!");
                        }
                        boolean flag = connectServer(port, hostIp, name);
                        if (flag == false) {
                            throw new Exception("与服务器连接失败!");
                        }
                        frame.setTitle(name);
                        listModel.addElement("全部用户");
                    } catch (Exception exc) {
                        JOptionPane.showMessageDialog(frame, exc.getMessage(),
                                "错误", JOptionPane.ERROR_MESSAGE);
                        return;
                    }
                }


                sendMessage("USERZHUCE#"+message_name+"#"+message_pw+"#"+message_yx);
            }
        });
        logPanle.add(btn_zhuce);



        txt_login_forget = new JTextField("");
        txt_login_forget.setFont(font);
        logPanle.add(txt_login_forget);

        btn_forget_pass = new JButton("密码找回");
        btn_forget_pass.setFont(font);
        btn_forget_pass.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                int port;

                String message_name = txt_login_name.getText().trim();
                if (message_name == null || message_name.equals("")) {
                    JOptionPane.showMessageDialog(logPanle, "用户名不能为空！", "错误",
                            JOptionPane.ERROR_MESSAGE);
                    return;
                }
                String message_yx = txt_login_forget.getText().trim();
                if (message_yx == null || message_yx.equals("")) {
                    JOptionPane.showMessageDialog(logPanle, "注册邮箱不能为空！", "错误",
                            JOptionPane.ERROR_MESSAGE);
                    return;
                }
                String message_pw = txt_password.getText().trim();
                if (message_pw == null || message_pw.equals("")) {
                    JOptionPane.showMessageDialog(logPanle, "修改密码不能为空！", "错误",
                            JOptionPane.ERROR_MESSAGE);
                    return;
                }

                if (isConnected) {
                    String message1 = txt_login_name.getText().trim();
                    if (message1 == null || message1.equals("")) {
                        JOptionPane.showMessageDialog(logPanle, "用户名不能为空！", "错误",
                                JOptionPane.ERROR_MESSAGE);
                        return;
                    }
                    String message2 = txt_login_forget.getText().trim();
                    if (message2 == null || message2.equals("")) {
                        JOptionPane.showMessageDialog(logPanle, "注册邮箱不能为空！", "错误",
                                JOptionPane.ERROR_MESSAGE);
                        return;
                    }
                    String message3 = txt_password.getText().trim();
                    if (message3 == null || message3.equals("")) {
                        JOptionPane.showMessageDialog(logPanle, "修改密码不能为空！", "错误",
                                JOptionPane.ERROR_MESSAGE);
                        return;
                    }
                    sendMessage("USERFORGET#"+message1+"#"+message2+"#"+message3);
                    return;
                }else{
                    try {
                        try {
                            port = Integer.parseInt(txt_login_port.getText().trim());
                        } catch (NumberFormatException e2) {
                            throw new Exception("端口号不符合要求!端口为整数!");
                        }
                        String hostIp = txt_login_ip.getText().trim();
                        String name = txt_login_name.getText().trim();
                        if (name.equals("") || hostIp.equals("")) {
                            throw new Exception("姓名、服务器IP不能为空!");
                        }
                        boolean flag = connectServer(port, hostIp, name);
                        if (flag == false) {
                            throw new Exception("与服务器连接失败!");
                        }
                        frame.setTitle(name);
                        listModel.addElement("全部用户");
                    } catch (Exception exc) {
                        JOptionPane.showMessageDialog(frame, exc.getMessage(),
                                "错误", JOptionPane.ERROR_MESSAGE);
                        return;
                    }
                }

                sendMessage("USERFORGET#"+message_name+"#"+message_yx+"#"+message_pw);
            }
        });
        logPanle.add(btn_forget_pass);


        logPanle.setBorder(new TitledBorder("登陆"));
        loginframe = new JFrame("登陆窗口");
        loginframe.add(logPanle,"Center");
        loginframe.setSize(300, 300);
        int screen_width = Toolkit.getDefaultToolkit().getScreenSize().width;
        int screen_height = Toolkit.getDefaultToolkit().getScreenSize().height;
        loginframe.setLocation((screen_width - loginframe.getWidth()) / 2,
                (screen_height - loginframe.getHeight()) / 2);
        loginframe.setVisible(true);

        // 关闭窗口时事件
        loginframe.addWindowListener(new WindowAdapter() {
            public void windowClosing(WindowEvent e) {
                if (isConnected) {
                    closeConnection();// 关闭连接
                    closeServer();//关闭服务程序
                }
                System.exit(0);// 退出程序
            }
        });
    }

    // 构造方法
    public Client() throws BindException {

        serverStart(0);

        SelecTry selectIndex=new SelecTry();

        textArea = new JTextArea();
        textArea.setEditable(false);
        textArea.setForeground(Color.blue);
        textField = new JTextField();
        txt_port = new JTextField("6666");
        txt_hostIp = new JTextField("127.0.0.1");
        txt_name = new JTextField("姓名");
        btn_start = new JButton("连接");
        btn_stop = new JButton("断开");
        btn_send = new JButton("发送");
        btn_send_file = new JButton("文件");
        listModel = new DefaultListModel();
        userList = new JList(listModel);
        //listModel.addElement("全部用户");
        userList.addListSelectionListener(selectIndex);
        northPanel = new JPanel();
        northPanel.setLayout(new GridLayout(1, 7));
        northPanel.add(new JLabel("     端口"));
        northPanel.add(txt_port);
        northPanel.add(new JLabel("    服务器IP"));
        northPanel.add(txt_hostIp);
        northPanel.add(new JLabel("     姓名"));
        northPanel.add(txt_name);
        northPanel.add(btn_start);
        northPanel.add(btn_stop);
        northPanel.setBorder(new TitledBorder("连接信息"));

        rightScroll = new JScrollPane(textArea);
        rightScroll.setBorder(new TitledBorder("消息显示区"));
        leftScroll = new JScrollPane(userList);
        leftScroll.setBorder(new TitledBorder("用户列表"));
        southPanel = new JPanel(new BorderLayout());
        sendPanel = new JPanel(new BorderLayout());
        southPanel.setBorder(new TitledBorder("写消息"));
        southPanel.add(textField, "Center");
        sendPanel.add(btn_send, BorderLayout.NORTH);
        sendPanel.add(btn_send_file, BorderLayout.SOUTH);
        southPanel.add(sendPanel, "East");


        centerSplit = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT, leftScroll,
                rightScroll);
        centerSplit.setDividerLocation(150);

        frame = new JFrame("客户机");
        // 更改JFrame的图标：
        //frame.setIconImage(Toolkit.getDefaultToolkit().createImage(Client.class.getResource("qq.png")));
        frame.setLayout(new BorderLayout());
        frame.add(northPanel, "North");
        frame.add(centerSplit, "Center");
        frame.add(southPanel, "South");
        frame.setSize(600, 400);
        int screen_width = Toolkit.getDefaultToolkit().getScreenSize().width;
        int screen_height = Toolkit.getDefaultToolkit().getScreenSize().height;
        frame.setLocation((screen_width - frame.getWidth()) / 2,
                (screen_height - frame.getHeight()) / 2);
        frame.setVisible(false);

        // 写消息的文本框中按回车键时事件
        textField.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0) {
                send();
            }
        });

        // 单击发送按钮时事件
        btn_send.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                send();
            }
        });

        //单机文件按钮时事件
        btn_send_file.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0) {
                sendFile();
            }
        });

        // 单击连接按钮时事件
//        btn_start.addActionListener(new ActionListener() {
//            public void actionPerformed(ActionEvent e) {
//                int port;
//                if (isConnected) {
//                    JOptionPane.showMessageDialog(frame, "已处于连接上状态，不要重复连接!",
//                            "错误", JOptionPane.ERROR_MESSAGE);
//                    return;
//                }
//                try {
//                    try {
//                        port = Integer.parseInt(txt_port.getText().trim());
//                    } catch (NumberFormatException e2) {
//                        throw new Exception("端口号不符合要求!端口为整数!");
//                    }
//                    String hostIp = txt_hostIp.getText().trim();
//                    String name = txt_name.getText().trim();
//                    if (name.equals("") || hostIp.equals("")) {
//                        throw new Exception("姓名、服务器IP不能为空!");
//                    }
//                    boolean flag = connectServer(port, hostIp, name);
//                    if (flag == false) {
//                        throw new Exception("与服务器连接失败!");
//                    }
//                    listModel.addElement("全部用户");
//                    frame.setTitle(name);
//                    JOptionPane.showMessageDialog(frame, "成功连接!");
//                } catch (Exception exc) {
//                    JOptionPane.showMessageDialog(frame, exc.getMessage(),
//                            "错误", JOptionPane.ERROR_MESSAGE);
//                }
//            }
//        });

        // 单击断开按钮时事件
        btn_stop.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                if (!isConnected) {
                    JOptionPane.showMessageDialog(frame, "已处于断开状态，不要重复断开!",
                            "错误", JOptionPane.ERROR_MESSAGE);
                    return;
                }
                try {
                    boolean flag = closeConnection();// 断开连接
                    closeServer();
                    if (flag == false) {
                        throw new Exception("断开连接发生异常！");
                    }
                    JOptionPane.showMessageDialog(frame, "成功断开!");
                    frame.setVisible(false);
                    textArea.setText("");
                    loginframe.setVisible(true);
                    listModel.removeAllElements();
                } catch (Exception exc) {
                    JOptionPane.showMessageDialog(frame, exc.getMessage(),
                            "错误", JOptionPane.ERROR_MESSAGE);
                }
            }
        });

        // 关闭窗口时事件
        frame.addWindowListener(new WindowAdapter() {
            public void windowClosing(WindowEvent e) {
                if (isConnected) {
                    closeConnection();// 关闭连接
                    closeServer();//关闭服务程序
                }
                System.exit(0);// 退出程序
            }
        });
        Login();
    }

    /**
     * 连接服务器
     *
     * @param port
     * @param hostIp
     * @param name
     */
    public boolean connectServer(int port, String hostIp, String name) {
        // 连接服务器
        try {
            socket = new Socket(hostIp, port);// 根据端口号和服务器ip建立连接
            writer = new PrintWriter(socket.getOutputStream());
            reader = new BufferedReader(new InputStreamReader(socket
                    .getInputStream()));
            // 发送客户端用户基本信息(用户名和ip地址)
            sendMessage(name + "#" + socket.getLocalAddress().toString());
            // 开启接收消息的线程
            messageThread = new MessageThread(reader, textArea);
            messageThread.start();
            isConnected = true;// 已经连接上了
            return true;
        } catch (Exception e) {
            textArea.append("与端口号为：" + port + "    IP地址为：" + hostIp
                    + "   的服务器连接失败!" + "
");
            isConnected = false;// 未连接上
            return false;
        }
    }

    /**
     * 发送消息
     *
     * #param message
     */
    public void sendMessage(String message) {
        writer.println(message);
        writer.flush();
    }

    /**
     * 客户端主动关闭连接
     */
    @SuppressWarnings("deprecation")
    public synchronized boolean closeConnection() {
        try {
            sendMessage("CLOSE");// 发送断开连接命令给服务器
            messageThread.stop();// 停止接受消息线程
            // 释放资源
            if (reader != null) {
                reader.close();
            }
            if (writer != null) {
                writer.close();
            }
            if (socket != null) {
                socket.close();
            }
            isConnected = false;
            listModel.removeAllElements();
            return true;
        } catch (IOException e1) {
            e1.printStackTrace();
            isConnected = true;
            return false;
        }
    }

    // 不断接收消息的线程
    class MessageThread extends Thread {
        private BufferedReader reader;
        private JTextArea textArea;

        // 接收消息线程的构造方法
        public MessageThread(BufferedReader reader, JTextArea textArea) {
            this.reader = reader;
            this.textArea = textArea;
        }

        // 被动的关闭连接
        public synchronized void closeCon() throws Exception {
            // 清空用户列表
            listModel.removeAllElements();
            // 被动的关闭连接释放资源
            if (reader != null) {
                reader.close();
            }
            if (writer != null) {
                writer.close();
            }
            if (socket != null) {
                socket.close();
            }
            isConnected = false;// 修改状态为断开

        }

        public void run() {
            String message = "";
            while (true) {
                try {
                    message = reader.readLine();
                    StringTokenizer stringTokenizer = new StringTokenizer(
                            message, "/#");
                    String command = stringTokenizer.nextToken();// 命令
                    if (command.equals("CLOSE"))// 服务器已关闭命令
                    {
                        textArea.append("服务器已关闭!
");
                        closeCon();// 被动的关闭连接
                        JOptionPane.showMessageDialog(frame, "服务器已关闭！", "错误",
                                JOptionPane.ERROR_MESSAGE);
                        frame.setVisible(false);
                        textArea.setText("");
                        loginframe.setVisible(true);
                        return;// 结束线程
                    } else if (command.equals("ADD")) {// 有用户上线更新在线列表
                        String username = "";
                        String userIp = "";
                        if ((username = stringTokenizer.nextToken()) != null
                                && (userIp = stringTokenizer.nextToken()) != null) {
                            User user = new User(username, userIp);
                            onLineUsers.put(username, user);
                            listModel.addElement(username);
                        }
                    } else if (command.equals("DELETE")) {// 有用户下线更新在线列表
                        String username = stringTokenizer.nextToken();
                        User user = (User) onLineUsers.get(username);
                        onLineUsers.remove(user);
                        listModel.removeElement(username);
                    } else if (command.equals("USERLIST")) {// 加载在线用户列表
                        listModel.removeAllElements();
                        listModel.addElement("全部用户");
                        StringTokenizer strToken ;
                        String user ;// 命令
                        int size = Integer
                                .parseInt(stringTokenizer.nextToken());
                        String username = null;
                        String userIp = null;
                        for (int i = 0; i < size-1; i++) {
                            username = stringTokenizer.nextToken();
                            strToken = new StringTokenizer(username, "---()");
                            if (strToken.nextToken().equals(frame.getTitle())) {
                                continue;
                            }else{
                                listModel.addElement(username);
                            }
                            //userIp = stringTokenizer.nextToken();
                            //User user = new User(username, userIp);
                            //onLineUsers.put(username, user);
                        }
                    } else if (command.equals("MAX")) {// 人数已达上限
                        textArea.append(stringTokenizer.nextToken()
                                + stringTokenizer.nextToken() + "
");
                        closeCon();// 被动的关闭连接
                        JOptionPane.showMessageDialog(frame, "服务器缓冲区已满！", "错误",
                                JOptionPane.ERROR_MESSAGE);
                        return;// 结束线程
                    } else if(command.equals("FILE")){
                        int portNumber = Integer.parseInt(stringTokenizer.nextToken());
                        String fileName = stringTokenizer.nextToken();
                        long fileSize = Long.parseLong(stringTokenizer.nextToken());
                        String ip = stringTokenizer.nextToken();
                        String Nickname = stringTokenizer.nextToken();
                        ReceiveFileThread receiveFile = new ReceiveFileThread(textArea,frame,ip, portNumber, fileName, fileSize, Nickname);
                        receiveFile.start();
                        textArea.append("从"+Nickname+"接受文件:"+fileName+",大小为:"+fileSize
                                +"ip:"+ip+"port:"+portNumber+"
");
                    }else if(command.equals("USERLOGIN")){
                        String st = stringTokenizer.nextToken();
                        if(st.equals("OK")){
                            JOptionPane.showMessageDialog(loginframe, "登陆成功!" );
                            loginframe.setVisible(false);
                            txt_name.setText(txt_login_name.getText());
                            frame.setVisible(true);
                            int count = stringTokenizer.countTokens();
                            while(true){
                                if(count==0){
                                    break;
                                }
                                textArea.append(stringTokenizer.nextToken()+"  对你留言 ，");
                                textArea.append("时间： "+stringTokenizer.nextToken()+"
   ");
                                textArea.append("留言内容： "+stringTokenizer.nextToken()+"
");
                                count-=3;
                            }

                        }else if(st.equals("ALREADY")){
                            JOptionPane.showMessageDialog(loginframe, "账号已登陆!" );
                        }else{
                            JOptionPane.showMessageDialog(loginframe, "登陆失败!" );
                        }
                    }else if(command.equals("USERZHUCE")){
                        String st = stringTokenizer.nextToken();
                        if(st.equals("OK")){
                            JOptionPane.showMessageDialog(loginframe, "注册成功!" );

                        }else if(st.equals("exict")){
                            JOptionPane.showMessageDialog(loginframe, "用户名已存在!" );
                        }else{
                            JOptionPane.showMessageDialog(loginframe, "注册失败!" );
                        }
                    }else if(command.equals("USERFORGET")){
                        String st = stringTokenizer.nextToken();
                        if(st.equals("OK")){
                            JOptionPane.showMessageDialog(loginframe, "修改密码成功!" );

                        }else if(st.equals("YOUXIANG_WRONG")){
                            JOptionPane.showMessageDialog(loginframe, "邮箱错误!" );
                        }else if(st.equals("NAME_NO_exict")){
                            JOptionPane.showMessageDialog(loginframe, "用户不存在!" );
                        }else{
                            JOptionPane.showMessageDialog(loginframe, "找回密码失败!" );
                        }
                    } else if (command.equals("P2P")) {
                        String st = stringTokenizer.nextToken();
                        if(st.equals("OK")){
                            String username = stringTokenizer.nextToken();
                            int serverPort = Integer.parseInt(stringTokenizer.nextToken());
                            String ip = stringTokenizer.nextToken();
                            boolean cn = connectServer_p2p(serverPort,ip,username);
                            if (cn) {
                                JOptionPane.showMessageDialog(frame, "与"+username+"的连接成功，端口号为："+serverPort+"IP:"+ip );
                                P2P_printWriter.println(frame.getTitle()+"#"+myIP);
                                P2P_printWriter.flush();

                                String msg = textField.getText().trim();
                                P2P_printWriter.println(msg);
                                P2P_printWriter.flush();

                                textArea.append("对  "+username+"  说： "+msg+"
");

                                textField.setText(null);
                            }

                        }else{
                            String username = stringTokenizer.nextToken();
                            JOptionPane.showMessageDialog(frame, "与"+username+"的连接失败！");
                        }
                    } else {// 普通消息
                        textArea.append(message + "
");
                    }
                } catch (IOException e) {
                    e.printStackTrace();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

package com.company;

import javax.swing.*;
import java.io.*;
import java.net.ServerSocket;
import java.net.Socket;


public class SendFileThread extends Thread {
    private Socket clientSocket;
    private String name;
    JFileChooser sourceFileChooser;
    int status;
    JFrame JFrame;

    public SendFileThread(JFrame frame, Socket socket, String name, JFileChooser sourceFileChooser, int status) {
        this.clientSocket = socket;
        this.name = name;
        this.sourceFileChooser = sourceFileChooser;
        this.status = status;
        this.JFrame = frame;
    }

    public void run() {
//        JFileChooser sourceFileChooser = new JFileChooser(".");
//        sourceFileChooser.setFileSelectionMode(JFileChooser.FILES_ONLY);
//        int status = sourceFileChooser.showOpenDialog(null);
        if (status == JFileChooser.APPROVE_OPTION) {
            File sourceFile = new File(sourceFileChooser.getSelectedFile().getPath());
            String sourceFilePath = sourceFile.getAbsolutePath();
            String fileName = sourceFile.getName();
            //System.out.println(sourceFilePath+"\"+fileName);
            try {
                PrintWriter sendToClient = new PrintWriter(clientSocket.getOutputStream());
                BufferedReader getFromClient = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
                ServerSocket fileSenderSocket = null;
                try {
                    fileSenderSocket = new ServerSocket(0);
                } catch (IOException ex1) {
                    JOptionPane.showMessageDialog(JFrame, "无法分配端口以发送此文件!", "错误", JOptionPane.ERROR_MESSAGE);
                }
                sendToClient.println("FILE#" + fileSenderSocket.getLocalPort() + "#" + fileName + "#"
                        + String.valueOf(sourceFile.length()) + "#" + clientSocket.getLocalAddress() + "#" + name);
                sendToClient.flush();
                //System.out.println("Sender: "+fileSenderSocket.getLocalSocketAddress());
                Socket fileReceiverSocket = fileSenderSocket.accept();

                BufferedReader getFromReceiver = null;
                PrintWriter sendToReceiver = null;
                try {
                    getFromReceiver = new BufferedReader(new InputStreamReader(fileReceiverSocket.getInputStream()));
                    sendToReceiver = new PrintWriter(fileReceiverSocket.getOutputStream());
                } catch (IOException ex) {
                } finally {
                }
                String judge = getFromReceiver.readLine();
                if (judge.equals("accepted")) {
                    DataOutputStream sendFileToReceiver = new DataOutputStream(new BufferedOutputStream(fileReceiverSocket.getOutputStream()));
                    ProgressMonitorInputStream monitor;
                    FileInputStream sendFileStream = null;
                    try {
                        sendFileStream = new FileInputStream(sourceFile);
                    } catch (FileNotFoundException ex) {
                        sendToReceiver.flush();
                        sendFileToReceiver.writeByte(0);
                        sendFileToReceiver.flush();
                        return;
                    }
                    monitor = new ProgressMonitorInputStream(JFrame, "正在发送： " + fileName, sendFileStream);
                    ProgressMonitor progressMonitor = monitor.getProgressMonitor();

                    int read_unit = 500;
                    long fileSize = monitor.available();
                    int readed = 0;
                    byte[] data = new byte[read_unit];
                    try {
                        sendFileToReceiver.writeByte(1);
                        sendFileToReceiver.flush();
                        while (monitor.available() > 0) {
                            int in = monitor.read(data);
                            readed += in;
                            float process = (float) readed / fileSize * 100;
                            progressMonitor.setNote(process + " % 完成");
                            if (in > 0) {
                                sendFileToReceiver.write(data, 0, in);
                            }
                        }
                        sendFileToReceiver.flush();
                    } catch (IOException e) {
                        JOptionPane.showMessageDialog(JFrame, "传输中断!", "错误", JOptionPane.ERROR_MESSAGE);
                    } finally {
                        if (sendFileStream != null)
                            try {
                                sendFileStream.close();
                                monitor.close();
                            } catch (IOException e) {
                            }
                    }
                    try {
                        fileReceiverSocket.close();
                    } catch (IOException ex1) {
                    }
                } else if (judge.equals("refused")) {
                    JOptionPane.showMessageDialog(JFrame, "对方拒绝接受文件 " + fileName, "错误！", JOptionPane.INFORMATION_MESSAGE);
                }

            } catch (IOException ex) {
            } finally {
            }
        }
    }
}

package com.company;
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;

import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JTextArea;
import javax.swing.ProgressMonitor;
import javax.swing.ProgressMonitorInputStream;


public class ReceiveFileThread extends Thread {
    private String fileSenderIPAddress;
    private int fileSenderPortNumber;
    private String fileName;
    private long fileSize;
    private String otherNickname;
    JFrame frame;
    JTextArea textArea;

    public ReceiveFileThread(JTextArea textArea,JFrame frame,String ip, int port_number, String file_name, long file_size, String other_nickname) {
        this.fileSenderIPAddress = ip;
        this.fileSenderPortNumber = port_number;
        this.fileName = file_name;
        this.fileSize = file_size;
        this.otherNickname = other_nickname;
        this.frame = frame;
        this.textArea = textArea;
    }

    public void run() {
        Socket fileSenderSocket = null;
        try {
            fileSenderSocket = new Socket(fileSenderIPAddress, fileSenderPortNumber);
        }
        catch(IOException ex) {
            JOptionPane.showMessageDialog(frame, "无法连接到服务器接收文件!", "错误", JOptionPane.ERROR_MESSAGE);
        }
        finally {
        }
        DataInputStream getFromSender = null;
        DataOutputStream sendToSender = null;
        try {
            getFromSender = new DataInputStream(new BufferedInputStream(fileSenderSocket.getInputStream()));
            sendToSender = new DataOutputStream(new BufferedOutputStream(fileSenderSocket.getOutputStream()));
            BufferedReader getInfoFromSender =new BufferedReader(new InputStreamReader(getFromSender));

            int permit = JOptionPane.showConfirmDialog(frame, "接受文件:"+fileName+" 从 "+otherNickname+"?", "文件传输请求：", JOptionPane.YES_NO_OPTION);
            if(permit == JOptionPane.YES_OPTION) {
                sendToSender.writeBytes("accepted
");
                sendToSender.flush();

                JFileChooser destinationFileChooser = new JFileChooser(".");
                destinationFileChooser.setFileSelectionMode(JFileChooser.DIRECTORIES_ONLY);
                int status = destinationFileChooser.showSaveDialog(frame);
                File destinationPath = null;
                if (status == JFileChooser.APPROVE_OPTION) {
                    destinationPath = new File(destinationFileChooser.getSelectedFile().getPath());
                    //String destinationFile = destinationPath.getAbsolutePath()+"\"+fileName;
                    //System.out.println(destinationFilePath);
                }
                try {
                    byte judge = getFromSender.readByte();
                    if (judge > 0) {
                        File savedFile = new File(destinationPath.getAbsolutePath()+"\"+fileName);
                        FileOutputStream saveFileStream = new FileOutputStream(savedFile);
                        DataOutputStream fileOutput = new DataOutputStream(saveFileStream);
                        ProgressMonitorInputStream monitor = new ProgressMonitorInputStream(frame, "接受文件： "+fileName, getFromSender);
                        //ProgressMonitor progressMonitor = new ProgressMonitor(null, "Receiving "+fileName, "", 0, (int)fileSize);
                        ProgressMonitor progressMonitor = monitor.getProgressMonitor();
                        progressMonitor.setMaximum((int)fileSize);

                        int read_unit = 500;
                        int readed = 0;
                        float process = 0;
                        try {
                            while (true) {
                                byte[] data = new byte[read_unit];
                                int in = monitor.read(data);
                                readed += in;
                                process = (float) readed / fileSize * 100;
                                progressMonitor.setNote(process+" % 完成");
                                progressMonitor.setProgress(readed);
                                if (in <= 0) {
                                    break;
                                }
                                fileOutput.write(data,0,in);
                            }

                            fileOutput.flush();
                            if(savedFile.length() < fileSize) {
                                JOptionPane.showMessageDialog(frame, "传输中断!", "错误", JOptionPane.ERROR_MESSAGE);
                            }
                            textArea.append("接受文件："+fileName+"    保存地址："+destinationPath+"
");
                        }
                        catch(IOException e){
                            JOptionPane.showMessageDialog(frame, "传输中断!", "错误", JOptionPane.ERROR_MESSAGE);
                        }
                        finally {
                            try {
                                fileOutput.close();
                                saveFileStream.close();
                                progressMonitor.close();
                            }
                            catch(IOException e){
                            }
                        }
                    }
                    else {
                        JOptionPane.showMessageDialog(frame, "源文件没有找到!", "错误", JOptionPane.ERROR_MESSAGE);
                    }
                }
                catch(IOException e){
                }
                finally {
                    fileSenderSocket.close();
                }
            }
            else if(permit == JOptionPane.NO_OPTION) {
                sendToSender.writeBytes("refused
");
                sendToSender.flush();
            }
        }
        catch(IOException ex) {
        }
        finally {
        }
        //System.out.println("Receiver: "+fileReceiverSocket.getRemoteSocketAddress());
    }

}

package com.company;

//用户信息类
public class User{
    private String name;
    private String ip;
    private int state;

    public User(String name, String ip) {
        this.name = name;
        this.ip = ip;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getIp() {
        return ip;
    }

    public void setIp(String ip) {
        this.ip = ip;
    }

    public int getState() {
        return state;
    }

    public void setState(int state){
        this.state=state;
    }
}

是一次实验课的第一次实验，可能还有bug，请理解！

后期会更新。