初学C#的SOCKET编程，照着网上的代码写下来，程序总是有问题，经过自己长时间的调试，完成程序，以下是原码，有需要可以参考一下，还不完善，欢迎大家批评指正。（这里的代码没更新，附件重新上传更新，在另一个线程中使用委托来修改控件的属性，发送广播功能还有问题，稍修更新修正。）

环境：VS2008 .NET3.5

网上给出的程序都是控制台程序，我这个是WINFORM程序。有详细的说明，以服务端程序。

需要增加的命名空间：

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

以下是具体实现。

namespace TCPServer
{
        public partial class Form1 : Form
        {
                public Form1()
                {
                        InitializeComponent();
                        
                }
                public bool btnstatu = true;    //开始停止服务按钮状态
                public Thread myThread;             //声明一个线程实例
                public Socket newsock;                //声明一个Socket实例
                public Socket Client;                    
                public IPEndPoint localEP;        
                public int localPort;
                public bool m_Listening;
                //用来设置服务端监听的端口号
                public int setPort                        
                {
                        get { return localPort; }
                        set { localPort = value; }
                }
                
                //用来往richtextbox框中显示消息
                public void showClientMsg(string msg)
                {
                        showClientMsg(msg+"\r\n");
                }
                //监听函数
                public void Listen()
                {     //设置端口
                        setPort=int.Parse(serverport.Text.Trim());
                        //初始化SOCKET实例
                        newsock = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
                        //初始化终结点实例
                        localEP=new IPEndPoint(IPAddress.Any,setPort);
                        try
                        {
                                //绑定
                                newsock.Bind(localEP);
                                //监听
                                newsock.Listen(10);
                                //用于设置按钮状态
                                m_Listening = true;
                                //开始接受连接，异步。
                                newsock.BeginAccept(new AsyncCallback(OnConnectRequest), newsock);
                         }
                        catch (Exception ex)
                        {
                                showClientMsg(ex.Message);
                        }

                }
                //当有客户端连接时的处理
                public void OnConnectRequest(IAsyncResult ar)
                {
                     //初始化一个SOCKET，用于其它客户端的连接
                        Socket server1 = (Socket)ar.AsyncState;
                        Client = server1.EndAccept(ar);
                        //将要发送给连接上来的客户端的提示字符串
                        string strDateLine = "Welcome here";
                        Byte[] byteDateLine = System.Text.Encoding.ASCII.GetBytes(strDateLine);
                        //将提示信息发送给客户端
                        Client.Send(byteDateLine, byteDateLine.Length, 0);
                        //等待新的客户端连接
                        server1.BeginAccept(new AsyncCallback(OnConnectRequest), server1);
                        while (true)
                        {
                                int recv = Client.Receive(byteDateLine);
                                string stringdata = Encoding.ASCII.GetString(byteDateLine, 0, recv);
                                DateTimeOffset now = DateTimeOffset.Now;
                                //获取客户端的IP和端口
                                string ip = Client.RemoteEndPoint.ToString();
                                if (stringdata == "STOP")
                                {
                                        //当客户端终止连接时
                                        showinfo.AppendText(ip+"已从服务器断开");
                                        break;    
                                }
                                //显示客户端发送过来的信息
                                showinfo.AppendText(ip + "    " + now.ToString("G") + "     " + stringdata + "\r\n");                            
                        }
                                                
                }
            //开始停止服务按钮
                private void startService_Click(object sender, EventArgs e)
                {
                        //新建一个委托线程
                        ThreadStart myThreadDelegate = new ThreadStart(Listen);
                        //实例化新线程
                        myThread = new Thread(myThreadDelegate);
                            
                        if (btnstatu)
                        {
                                
                                myThread.Start();
                                statuBar.Text = "服务已启动，等待客户端连接";
                                btnstatu = false;
                                startService.Text = "停止服务";
                        }
                        else
                        {
                                //停止服务（功能还有问题，无法停止）
                                m_Listening = false;
                                newsock.Close();
                                myThread.Abort();
                                showClientMsg("服务器停止服务");
                                btnstatu = true;
                                startService.Text = "开始服务";
                                statuBar.Text = "服务已停止";
                                m_Listening = false;
                        }
                            
                }
                //窗口关闭时中止线程。
                private void Form1_FormClosing(object sender, FormClosingEventArgs e)
                {
                        if (myThread != null)
                        {
                                myThread.Abort();
                        }
                }
        }


}