C#编写聊天软件服务端

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net.Sockets;
using System.IO;

namespace SyncChatServer
{
    class User
    {
        public TcpClient client { get; private set; }
        public BinaryReader br { get; private set; }
        public BinaryWriter bw { get; private set; }
        public string userName { get; set; }

        public User(TcpClient client)
        {
            this.client = client;
            NetworkStream networkStream = client.GetStream();
            br = new BinaryReader(networkStream);
            bw = new BinaryWriter(networkStream);
        }

        public void Close()
        {
            br.Close();
            bw.Close();
            client.Close();
        }

    }
}

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Net;
using System.Net.Sockets;
using System.Threading;
using System.IO;

namespace SyncChatServer
{
    public partial class MainForm : Form
    {
        /// <summary>
        /// 保存连接的所有用户
        /// </summary>
        private List<User> userList = new List<User>();

        /// <summary>
        /// 服务器IP地址
        /// </summary>;
        private string ServerIP;

        /// <summary>
        /// 监听端口
        /// </summary>
        private int port;
        private TcpListener myListener;

        /// <summary>
        /// 是否正常退出所有接收线程
        /// </summary>
        bool isNormalExit = false;

        public MainForm()
        {
            InitializeComponent();
            lst_State.HorizontalScrollbar = true;
            btn_Stop.Enabled = false;
            SetServerIPAndPort();
        }

        /// <summary>
        /// 根据当前程序目录的文本文件‘ServerIPAndPort.txt’内容来设定IP和端口
        /// 格式：127.0.0.1:8885
        /// </summary>
        private void SetServerIPAndPort()
        {
            FileStream fs = new FileStream("ServerIPAndPort.txt", FileMode.Open);
            StreamReader sr = new StreamReader(fs);
            string IPAndPort = sr.ReadLine();
            ServerIP = IPAndPort.Split(':')[0]; //设定IP
            port = int.Parse(IPAndPort.Split(':')[1]); //设定端口
            sr.Close();
            fs.Close();
        }


        /// <summary>
        /// 开始监听
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void btn_Start_Click(object sender, EventArgs e)
        {
            myListener = new TcpListener(IPAddress.Parse(ServerIP), port);
            myListener.Start();
            AddItemToListBox(string.Format("开始在{0}:{1}监听客户连接", ServerIP, port));
            //创建一个线程监客户端连接请求
            Thread myThread = new Thread(ListenClientConnect);
            myThread.Start();
            btn_Start.Enabled = false;
            btn_Stop.Enabled = true;
        }

        /// <summary>
        /// 接收客户端连接
        /// </summary>
        private void ListenClientConnect()
        {
            TcpClient newClient = null;
            while (true)
            {
                try
                {
                    newClient = myListener.AcceptTcpClient();
                }
                catch
                {
                    //当单击‘停止监听’或者退出此窗体时 AcceptTcpClient() 会产生异常
                    //因此可以利用此异常退出循环
                    break;
                }
                //每接收一个客户端连接，就创建一个对应的线程循环接收该客户端发来的信息；
                User user = new User(newClient);
                Thread threadReceive = new Thread(ReceiveData);
                threadReceive.Start(user);
                userList.Add(user);
                AddItemToListBox(string.Format("[{0}]进入", newClient.Client.RemoteEndPoint));
                AddItemToListBox(string.Format("当前连接用户数：{0}", userList.Count));
            }

        }

        /// <summary>
        /// 处理接收的客户端信息
        /// </summary>
        /// <param name="userState">客户端信息</param>
        private void ReceiveData(object userState)
        {
            User user = (User)userState;
            TcpClient client = user.client;
            while (isNormalExit == false)
            {
                string receiveString = null;
                try
                {
                    //从网络流中读出字符串，此方法会自动判断字符串长度前缀
                    receiveString = user.br.ReadString();
                }
                catch (Exception)
                {
                    if (isNormalExit == false)
                    {
                        AddItemToListBox(string.Format("与[{0}]失去联系，已终止接收该用户信息", client.Client.RemoteEndPoint));
                        RemoveUser(user);
                    }
                    break;
                }
                AddItemToListBox(string.Format("来自[{0}]：{1}",user.client.Client.RemoteEndPoint,receiveString));
                string[] splitString = receiveString.Split(',');
                switch(splitString[0])
                {
                    case "Login":
                        user.userName = splitString[1];
                        SendToAllClient(user,receiveString);
                        break;
                    case "Logout":
                        SendToAllClient(user,receiveString);
                        RemoveUser(user);
                        return;
                    case "Talk":
                        string talkString = receiveString.Substring(splitString[0].Length + splitString[1].Length + 2);
                        AddItemToListBox(string.Format("{0}对{1}说：{2}",user.userName,splitString[1],talkString));
                        SendToClient(user,"talk," + user.userName + "," + talkString);
                        foreach(User target in userList)
                        {
                            if(target.userName == splitString[1] && user.userName != splitString[1])
                            {
                                SendToClient(target,"talk," + user.userName + "," + talkString);
                                break;
                            }
                        }
                        break;
                    default:
                        AddItemToListBox("什么意思啊：" + receiveString);
                        break;
                }
            }
        }

        /// <summary>
        /// 发送消息给所有客户
        /// </summary>
        /// <param name="user">指定发给哪个用户</param>
        /// <param name="message">信息内容</param>
        private void SendToAllClient(User user, string message)
        {
            string command = message.Split(',')[0].ToLower();
            if (command == "login")
            {
                //获取所有客户端在线信息到当前登录用户
                for (int i = 0; i < userList.Count; i++)
                {
                    SendToClient(user, "login," + userList[i].userName);
                }
                //把自己上线，发送给所有客户端
                for (int i = 0; i < userList.Count; i++)
                {
                    if (user.userName != userList[i].userName)
                    {
                        SendToClient(userList[i], "login," + user.userName);
                    }
                }
            }
            else if(command == "logout")
            {
                for (int i = 0; i < userList.Count; i++)
                {
                    if (userList[i].userName != user.userName)
                    {
                        SendToClient(userList[i], message);
                    }
                }
            }
        }

        /// <summary>
        /// 发送 message 给 user
        /// </summary>
        /// <param name="user">指定发给哪个用户</param>
        /// <param name="message">信息内容</param>
        private void SendToClient(User user, string message)
        {
            try
            {
                //将字符串写入网络流，此方法会自动附加字符串长度前缀
                user.bw.Write(message);
                user.bw.Flush();
                AddItemToListBox(string.Format("向[{0}]发送：{1}", user.userName, message));
            }
            catch
            {
                AddItemToListBox(string.Format("向[{0}]发送信息失败",user.userName));
            }
        }

        /// <summary>
        /// 移除用户
        /// </summary>
        /// <param name="user">指定要移除的用户</param>
        private void RemoveUser(User user)
        {
            userList.Remove(user);
            user.Close();
            AddItemToListBox(string.Format("当前连接用户数：{0}",userList.Count));
        }

        private delegate void AddItemToListBoxDelegate(string str);
        /// <summary>
        /// 在ListBox中追加状态信息
        /// </summary>
        /// <param name="str">要追加的信息</param>
        private void AddItemToListBox(string str)
        {
            if (lst_State.InvokeRequired)
            {
                AddItemToListBoxDelegate d = AddItemToListBox;
                lst_State.Invoke(d, str);
            }
            else
            {
                lst_State.Items.Add(str);
                lst_State.SelectedIndex = lst_State.Items.Count - 1;
                lst_State.ClearSelected();
            }
        }

        /// <summary>
        /// 停止监听
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void btn_Stop_Click(object sender, EventArgs e)
        {
            AddItemToListBox("开始停止服务，并依次使用户退出！");
            isNormalExit = true;
            for (int i = userList.Count - 1; i >= 0; i--)
            {
                RemoveUser(userList[i]);
            }
            //通过停止监听让 myListener.AcceptTcpClient() 产生异常退出监听线程
            myListener.Stop();
            btn_Start.Enabled = true;
            btn_Stop.Enabled = false;
        }

        /// <summary>
        /// 关闭窗口时触发的事件
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void MainForm_FormClosing(object sender, FormClosingEventArgs e)
        {
            if (myListener != null)
                btn_Stop.PerformClick();    //引发 btn_Stop 的Click事件
        }
    }
}