NIO编程之多客户端聊天系统

1. 服务端

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.*;
import java.util.Iterator;
import java.util.Set;

public class GroupChatServer {
    private Selector selector;
    private ServerSocketChannel listenChannel;
    private static final int PORT = 8888;

    // 构造 器
    public GroupChatServer() {
        try {
            selector = Selector.open();
            listenChannel = ServerSocketChannel.open();
            // 绑定端口
            listenChannel.socket().bind(new InetSocketAddress(PORT));
            // 设置非阻塞模式
            listenChannel.configureBlocking(false);
            // 将listenChannel注册到selector
            listenChannel.register(selector, SelectionKey.OP_ACCEPT);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * 监听
     */
    public void listen() {
        try {
            while (true) {
                //select(2000) 只阻塞2秒
//                int count = selector.select(2000);
                // select()方法一直阻塞
                int count = selector.select();
                if (count > 0) {
                    // 遍历得到所有的SelectionKey集合

                    Iterator<SelectionKey> keysIterator = selector.selectedKeys().iterator();
                    while (keysIterator.hasNext()) {
                        // 处理每个selectionKey
                        SelectionKey selectionKey = keysIterator.next();
                        // 监听到连接事件
                        if (selectionKey.isAcceptable()) {
                            SocketChannel socketChannel = listenChannel.accept();
                            socketChannel.configureBlocking(false);
                            //注册
                            socketChannel.register(selector, SelectionKey.OP_READ);
                            // 提示上线
                            System.out.println(socketChannel.getRemoteAddress() + "上线");
                        }
                        // 通道可读事件
                        if (selectionKey.isReadable()) {
                            // todo 处理读
                            readMessage(selectionKey);
                        }
                        // 删除key,防止重复处理
                        keysIterator.remove();
                    }
                } else {
//                    System.out.println("等待中。。。。");
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }


    }

    /**
     * 读取客户端消息
     *
     * @param key
     */
    public void readMessage(SelectionKey key) {
        SocketChannel socketChannel = null;
        try {
            socketChannel = (SocketChannel) key.channel();
            ByteBuffer byteBuffer = ByteBuffer.allocate(1024);
            int read = socketChannel.read(byteBuffer);
            // 根据read值做处理，如果read > 0 说明真的读取到数据了
            if (read > 0) {
                String message = new String(byteBuffer.array());
                System.out.println("Form Client : " + message);
                // todo 向其它客户端 转发消息
                sendInfoToOtherClient(message, socketChannel);
            }

        } catch (IOException e) {
            try {
                System.out.println(socketChannel.getRemoteAddress() + "离线了。。。");
                // 离线之后取消注册
                key.cancel();
                // 关闭channel
                socketChannel.close();
            } catch (IOException e1) {
                e1.printStackTrace();
            }
        }
    }

    /**
     * 转发消息到其它客户端
     *
     * @param message 转发的消息
     * @param self    ： 排除的channel
     */
    public void sendInfoToOtherClient(String message, SocketChannel self) throws IOException {
        System.out.println("服务器转发消息中。。。");
        // 遍历所有注册到selector上的socketChannel,并排除自己
        Set<SelectionKey> keys = selector.keys();
        for (SelectionKey key : keys) {
            // 通过key取出对应的SocketChannel
            Channel targetChannel = key.channel();
            // 排除自己
            if (targetChannel instanceof SocketChannel && targetChannel != self) {
                SocketChannel target = (SocketChannel) targetChannel;
                // 将message 存储到buffer
                ByteBuffer buffer = ByteBuffer.wrap(message.getBytes());
                // 将buffer中的数据写入通道
                target.write(buffer);
            }

        }
    }

    public static void main(String[] args) {
        //创建对象
        GroupChatServer chatServer = new GroupChatServer();
        chatServer.listen();
    }
}

2. 客户端

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.SocketChannel;
import java.util.Iterator;
import java.util.Scanner;
import java.util.Set;

public class GroupChatClient {
    // 服务器ip
    private final String HOST = "127.0.0.1";
    // 服务器端口
    private final int PORT = 8888;
    private Selector selector;
    private SocketChannel socketChannel;
    private String username;

    public GroupChatClient() {
        try {
            selector = Selector.open();
            socketChannel = SocketChannel.open(new InetSocketAddress(HOST, PORT));
            socketChannel.configureBlocking(false);
            socketChannel.register(selector, SelectionKey.OP_READ);
            username = socketChannel.getLocalAddress().toString().substring(1);
            System.out.println(username + " ok！");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * 向服务端发送消息
     *
     * @param info 消息内容
     */
    public void sendInfo(String info) {
        info = username + "说：" + info;
        try {
            socketChannel.write(ByteBuffer.wrap(info.getBytes()));
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    /**
     * 从服务端 读取消息
     */
    public void readInfo() {
        try {
            int readChannels = selector.select(2000);
            if (readChannels > 0) {
                Set<SelectionKey> keys = selector.selectedKeys();
                Iterator<SelectionKey> keyInterator = keys.iterator();

                while (keyInterator.hasNext()) {
                    SelectionKey selectionKey = keyInterator.next();
                    if (selectionKey.isReadable()) {
                        // 得到读相关通道
                        SocketChannel socketChannel = (SocketChannel) selectionKey.channel();
                        ByteBuffer byteBuffer = ByteBuffer.allocate(1024);
                        socketChannel.read(byteBuffer);
                        //把buffer中的数据转成字符 串
                        String messge = new String(byteBuffer.array());
                        System.out.println( messge.trim());
                    }
                    //删除当前selectionKey
                    keyInterator.remove();
                }

            } else {
//                System.out.println("没有可用通道。。。。")

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

    public static void main(String[] args) {
        // 启动客户端
        GroupChatClient chatClient = new GroupChatClient();

        // 启动一个线程每隔2秒读取从服务端发送过来的数据
        new Thread() {
            @Override
            public void run() {
                while (true) {
                    chatClient.readInfo();
                    try {
                        Thread.currentThread().sleep(2000);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
        }.start();

        // 发送数据到服务端
        Scanner scanner = new Scanner(System.in);
        while (scanner.hasNext()) {
            String info = scanner.next();
            chatClient.sendInfo(info);
        }

    }
}