while (keepalive)
   {
    Byte[] buffer = new Byte[1024];
    int bufLen = 0;
    try
    {
     bufLen = client.Available ;
    
     client.Receive(buffer,0,bufLen,SocketFlags.None);
     if(bufLen==0)
      continue;   
    }
    catch(Exception ex)
    {
     MessageBox.Show("Receive Error:"+ex.Message);
     return;
    }
   
    string clientcommand = System.Text.Encoding.ASCII.GetString(buffer).Substring(0,bufLen);

    string[] tokens = clientcommand.Split(new Char[]{'|'});
    Console.WriteLine(clientcommand);

    if (tokens[0] == "CONN")
    {
     for(int n=0; n<clients.Count;n++)
     {
      Client cl = (Client)clients[n];
      SendToClient(cl, "JOIN|" + tokens[1]);
     }
     EndPoint ep = client.RemoteEndPoint;
     Client c = new Client(tokens[1], ep, clientservice, client);
    
     string message = "LIST|" + GetChatterList() +" ";
     SendToClient(c, message);

     clients.Add(c);

     lbClients.Items.Add(c);

    }
    if (tokens[0] == "CHAT")
    {
     for(int n=0; n<clients.Count;n++)
     {
      Client cl = (Client)clients[n];
      SendToClient(cl, clientcommand);
     }
    }
    if (tokens[0] == "PRIV")
    {
     string destclient = tokens[3];
     for(int n=0; n<clients.Count;n++)
     {
      Client cl = (Client)clients[n];
      if(cl.Name.CompareTo(tokens[3]) == 0)
       SendToClient(cl, clientcommand);
      if(cl.Name.CompareTo(tokens[1]) == 0)
       SendToClient(cl, clientcommand);
     }
    }
    if (tokens[0] == "GONE")
    {
     int remove = 0;
     bool found = false;
     int c = clients.Count;
     for(int n=0; n<clients.Count;n++)
     {
      Client cl = (Client)clients[n];
      SendToClient(cl, clientcommand);
      if(cl.Name.CompareTo(tokens[1]) == 0)
      {
       remove = n;
       found = true;
       lbClients.Items.Remove(cl);
      }
     }
     if(found)
      clients.RemoveAt(remove);
     client.Close();
     keepalive = false;
    }
   }
  }

  private string GetChatterList()
  {
   string result = "";

   for(int i=0;i<clients.Count;i++)
   {
    result += ((Client)clients[i]).Name+"|";
   }
   return result;

  }

  private void SendToClient(Client cl,string clientCommand)
  {
   Byte[] message = System.Text.Encoding.ASCII.GetBytes(clientCommand);
   Socket s = cl.Sock;
   if(s.Connected)
   {
    s.Send(message,message.Length,0);
   }
  }

  private void Form1_Load(object sender, System.EventArgs e)
  {
   clients = new ArrayList();
  }

  private void button1_Click(object sender, System.EventArgs e)
  {
   threadListen = new Thread(new ThreadStart(StartListening));
   threadListen.Start(); 
  }
 }
}

/**//***************************** client类 ********************/

/**//************************** 放于 chatServer 项目中 *********/

using System;
using System.Threading;

namespace Chat_Server
{
 using System.Net.Sockets;
 using System.Net;

 /**////
 /// Client 的摘要说明。
 ///
 public class Client
 {
  private Thread clthread;
  private EndPoint endpoint;
  private string name;
  private Socket sock;

  public Client(string _name, EndPoint _endpoint, Thread _thread, Socket _sock)
  {
   // TODO: 在此处添加构造函数逻辑
   clthread = _thread;
   endpoint = _endpoint;
   name = _name;
   sock = _sock;
  }

  public override string ToString()
  {
   return endpoint.ToString()+ " : " + name;
  }

  public Thread CLThread
  {
   get{return clthread;}
   set{clthread = value;}
  }

  public EndPoint Host
  {
   get{return endpoint;}
   set{endpoint = value;}
  }

  public string Name
  {
   get{return name;}
   set{name = value;}
  }

  public Socket Sock
  {
   get{return sock;}
   set{sock = value;}
  }
 }
}

/**//***************************** chatClient ************************************/

using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;

using System.IO;
using System.Net;
using System.Net.Sockets;
using System.Threading;

namespace Chat_Client
{
 /**//// <summary>
 /// Form1 的摘要说明。
 /// </summary>
 public class Form1 : System.Windows.Forms.Form
 {
  private System.Windows.Forms.CheckBox checkBox1;
  private System.Windows.Forms.StatusBar statusBar1;

  NetworkStream ns;
  StreamReader sr;
  TcpClient clientsocket;
  bool connected;
  Thread receive;
  string serveraddress = "219.228.231.85";
  int serverport = 6666;

  private System.Windows.Forms.RichTextBox rtbChatIn;
  private System.Windows.Forms.ListBox lbChatters;
  private System.Windows.Forms.TextBox ChatOut;
  private System.Windows.Forms.Button btnDisconnect;
  private System.Windows.Forms.Button btnSend;
  private System.Windows.Forms.TextBox clientName;

  string clientname;
  private System.Windows.Forms.Button btnConnect;

  private System.ComponentModel.Container components = null;

  public Form1()
  {
  
   InitializeComponent();

  }

  /**//// <summary>
  /// 清理所有正在使用的资源。
  /// </summary>
  protected override void Dispose( bool disposing )
  {
   if( disposing )
   {
    if(receive != null)
    {
     QuitChat();
    }
    if (components != null)
    {
     components.Dispose();
    }
   }
   base.Dispose( disposing );
  }

  Windows 窗体设计器生成的代码#region Windows 窗体设计器生成的代码
  /**//// <summary>
  /// 设计器支持所需的方法 - 不要使用代码编辑器修改
  /// 此方法的内容。
  /// </summary>
  private void InitializeComponent()
  {
   this.lbChatters = new System.Windows.Forms.ListBox();
   this.rtbChatIn = new System.Windows.Forms.RichTextBox();
   this.checkBox1 = new System.Windows.Forms.CheckBox();
   this.ChatOut = new System.Windows.Forms.TextBox();
   this.btnSend = new System.Windows.Forms.Button();
   this.statusBar1 = new System.Windows.Forms.StatusBar();
   this.btnDisconnect = new System.Windows.Forms.Button();
   this.clientName = new System.Windows.Forms.TextBox();
   this.btnConnect = new System.Windows.Forms.Button();
   this.SuspendLayout();
   //
   // lbChatters
   //
   this.lbChatters.ItemHeight = 12;
   this.lbChatters.Location = new System.Drawing.Point(32, 40);
   this.lbChatters.Name = "lbChatters";
   this.lbChatters.Size = new System.Drawing.Size(112, 172);
   this.lbChatters.TabIndex = 0;
   //
   // rtbChatIn
   //
   this.rtbChatIn.Location = new System.Drawing.Point(160, 40);
   this.rtbChatIn.Name = "rtbChatIn";
   this.rtbChatIn.Size = new System.Drawing.Size(208, 176);
   this.rtbChatIn.TabIndex = 2;
   this.rtbChatIn.Text = "";
   //
   // checkBox1
   //
   this.checkBox1.Location = new System.Drawing.Point(16, 248);
   this.checkBox1.Name = "checkBox1";
   this.checkBox1.TabIndex = 3;
   this.checkBox1.Text = "checkBox1";
   //
   // ChatOut
   //
   this.ChatOut.Location = new System.Drawing.Point(136, 248);
   this.ChatOut.Name = "ChatOut";
   this.ChatOut.Size = new System.Drawing.Size(136, 21);
   this.ChatOut.TabIndex = 4;
   this.ChatOut.Text = "message";
   //
   // btnSend
   //
   this.btnSend.Location = new System.Drawing.Point(336, 248);
   this.btnSend.Name = "btnSend";
   this.btnSend.TabIndex = 5;
   this.btnSend.Text = "send";
   this.btnSend.Click += new System.EventHandler(this.btnSend_Click);
   //
   // statusBar1
   //
   this.statusBar1.Location = new System.Drawing.Point(0, 287);
   this.statusBar1.Name = "statusBar1";
   this.statusBar1.Size = new System.Drawing.Size(464, 22);
   this.statusBar1.TabIndex = 6;
   this.statusBar1.Text = "statusBar1";
   //
   // btnDisconnect
   //
   this.btnDisconnect.Enabled = false;
   this.btnDisconnect.Location = new System.Drawing.Point(392, 112);
   this.btnDisconnect.Name = "btnDisconnect";
   this.btnDisconnect.Size = new System.Drawing.Size(64, 32);
   this.btnDisconnect.TabIndex = 7;
   this.btnDisconnect.Text = "断开";
   this.btnDisconnect.Click += new System.EventHandler(this.btnDisconnect_Click);
   //
   // clientName
   //
   this.clientName.Location = new System.Drawing.Point(96, 8);
   this.clientName.Name = "clientName";
   this.clientName.TabIndex = 8;
   this.clientName.Text = "name";
   //
   // btnConnect
   //
   this.btnConnect.Location = new System.Drawing.Point(392, 56);
   this.btnConnect.Name = "btnConnect";
   this.btnConnect.Size = new System.Drawing.Size(64, 32);
   this.btnConnect.TabIndex = 9;
   this.btnConnect.Text = "连接";
   this.btnConnect.Click += new System.EventHandler(this.btnConnect_Click);
   //
   // Form1
   //
   this.AutoScaleBaseSize = new System.Drawing.Size(6, 14);
   this.ClientSize = new System.Drawing.Size(464, 309);
   this.Controls.Add(this.btnConnect);
   this.Controls.Add(this.clientName);
   this.Controls.Add(this.btnDisconnect);
   this.Controls.Add(this.statusBar1);
   this.Controls.Add(this.btnSend);
   this.Controls.Add(this.ChatOut);
   this.Controls.Add(this.checkBox1);
   this.Controls.Add(this.rtbChatIn);
   this.Controls.Add(this.lbChatters);
   this.Name = "Form1";
   this.Text = "Form1";
   this.ResumeLayout(false);

  }
  #endregion

  /**//// <summary>
  /// 应用程序的主入口点。
  /// </summary>
  [STAThread]
  static void Main()
  {
   Application.Run(new Form1());
  }

  private void EstablishConnection()
  {
   statusBar1.Text = "正在连接到服务器";
  
   try
   {
    clientsocket = new TcpClient(serveraddress,serverport);
    ns = clientsocket.GetStream();
    sr = new StreamReader(ns);
    connected = true;
  
   }
   catch (Exception)
   {
    MessageBox.Show("不能连接到服务器！","错误",
     MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
    statusBar1.Text = "已断开连接";
   }
  }

  private void RegisterWithServer()
  {
   lbChatters.Items.Clear();

   clientname = clientName.Text;
   try
   {
    string command = "CONN|" + clientname; //+" ";
    Byte[] outbytes = System.Text.Encoding.ASCII.GetBytes(command.ToCharArray());
    ns.Write(outbytes,0,outbytes.Length);

    string serverresponse = sr.ReadLine();
    serverresponse.Trim();
    string[] tokens = serverresponse.Split('|');
    if(tokens[0] == "LIST")
    {
     statusBar1.Text = "已连接";
     btnDisconnect.Enabled = true;
    }
    if(tokens[1] != "")
    {
     for(int n=1; n<tokens.Length;n++)
      lbChatters.Items.Add(tokens[n].Trim(new char[]{' ',' '}));
    }
    this.Text = clientname + "：已连接到服务器";   

   }
   catch (Exception ex)
   {
    MessageBox.Show("注册时发生错误！"+ex.Message,"错误",
     MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
    connected = false;
   }
  }

  private void ReceiveChat()
  {
   bool keepalive = true;
   while (keepalive)
   {
    try
    {
     Byte[] buffer = new Byte[1024];  // 2048???
     ns.Read(buffer,0,buffer.Length);
     string chatter = System.Text.Encoding.ASCII.GetString(buffer);
     string[] tokens = chatter.Split(new Char[]{'|'});

     if (tokens[0] == "CHAT")
     {
      rtbChatIn.AppendText(tokens[1]);
//      if(logging)
//       logwriter.WriteLine(tokens[1]);
     }
     if (tokens[0] == "PRIV")
     {
      rtbChatIn.AppendText("Private from ");
      rtbChatIn.AppendText(tokens[1].Trim() );
      rtbChatIn.AppendText(tokens[2] + " ");
//      if(logging)
//      {
//       logwriter.Write("Private from ");
//       logwriter.Write(tokens[1].Trim() );
//       logwriter.WriteLine(tokens[2] + " ");
//      }
     }
     if (tokens[0] == "JOIN")
     {
      rtbChatIn.AppendText(tokens[1].Trim() );
      rtbChatIn.AppendText(" has joined the Chat ");
//      if(logging)
//      {
//       logwriter.WriteLine(tokens[1]+" has joined the Chat");
//      }
      string newguy = tokens[1].Trim(new char[]{' ',' '});
      lbChatters.Items.Add(newguy);
     }
     if (tokens[0] == "GONE")
     {
      rtbChatIn.AppendText(tokens[1].Trim() );
      rtbChatIn.AppendText(" has left the Chat ");
//      if(logging)
//      {
//       logwriter.WriteLine(tokens[1]+" has left the Chat");
//      }
      lbChatters.Items.Remove(tokens[1].Trim(new char[]{' ',' '}));
     }
     if (tokens[0] == "QUIT")
     {
      ns.Close();
      clientsocket.Close();
      keepalive = false;
      statusBar1.Text = "服务器端已停止";
      connected= false;
      btnSend.Enabled = false;
      btnDisconnect.Enabled = false;
     }
    }
    catch(Exception){}
   }
  }

  private void QuitChat()
  {
   if(connected)
   {
    try
    {
     string command = "GONE|" + clientname;
     Byte[] outbytes = System.Text.Encoding.ASCII.GetBytes(command.ToCharArray());
     ns.Write(outbytes,0,outbytes.Length);
     clientsocket.Close();
    }
    catch(Exception ex)
    {
     MessageBox.Show(ex.Message);
    }
   }
//   if(logging)
//    logwriter.Close();
   if(receive != null && receive.IsAlive)
    receive.Abort();
   this.Text = "客户端";
  
   connected = false;

  }

  private void btnSend_Click(object sender, System.EventArgs e)
  {
   if(connected)
   {
    try
    {
     string command = "CHAT|" + clientname+": "+ChatOut.Text+" ";
     Byte[] outbytes = System.Text.Encoding.ASCII.GetBytes(command.ToCharArray());
     ns.Write(outbytes,0,outbytes.Length);
     //clientsocket.Close();
    }
    catch(Exception ex)
    {
     MessageBox.Show(ex.Message);
    }
   }
  }

  private void btnConnect_Click(object sender, System.EventArgs e)
  {
   EstablishConnection();
   RegisterWithServer();
   if(connected)
   {  
    receive = new Thread(new ThreadStart(ReceiveChat));
    receive.Start();
   }
  }

  private void btnDisconnect_Click(object sender, System.EventArgs e)
  {
   QuitChat();
  }
 }
}