private void Form1_Load(object sender, EventArgs e)
         {
             Control.CheckForIllegalCrossThreadCalls = false;
         }
        private void btnListen_Click(object sender, EventArgs e)
        {
            //ip地址
            IPAddress ip = IPAddress.Parse(txtIP.Text);
           // IPAddress ip = IPAddress.Any;
            //端口号
            IPEndPoint point=new IPEndPoint(ip,int.Parse(txtPort.Text));
            //创建监听用的Socket
            /*
             * AddressFamily.InterNetWork：使用 IP4地址。
SocketType.Stream：支持可靠、双向、基于连接的字节流，而不重复数据。此类型的 Socket 与单个对方主机进行通信，并且在通信开始之前需要远程主机连接。Stream 使用传输控制协议 (Tcp) ProtocolType 和 InterNetworkAddressFamily。
ProtocolType.Tcp：使用传输控制协议。
             */
            //使用IPv4地址，流式socket方式，tcp协议传递数据
            Socket socket=new Socket(AddressFamily.InterNetwork,SocketType.Stream,ProtocolType.Tcp);
            //创建好socket后，必须告诉socket绑定的IP地址和端口号。
            //让socket监听point
            try
            {
                //socket监听哪个端口
                socket.Bind(point);
                //同一个时间点过来10个客户端，排队
                socket.Listen(10);
                ShowMsg("服务器开始监听");
                Thread thread = new Thread(AcceptInfo);
                thread.IsBackground = true;
                thread.Start(socket);
            }
            catch (Exception ex)
            {
               ShowMsg(ex.Message);
            }
        }
        //记录通信用的Socket
        Dictionary<string,Socket> dic=new Dictionary<string, Socket>();
       // private Socket client;
        void AcceptInfo(object o)
        {
            Socket socket = o as Socket;
            while (true)
            {
                //通信用socket
                try
                {
                     //创建通信用的Socket
                   Socket  tSocket = socket.Accept();
                   string point = tSocket.RemoteEndPoint.ToString();
                     //IPEndPoint endPoint = (IPEndPoint)client.RemoteEndPoint;
                     //string me = Dns.GetHostName();//得到本机名称
                     //MessageBox.Show(me);
                  ShowMsg(point + "连接成功！");
                  cboIpPort.Items.Add(point);
                  dic.Add(point, tSocket);
                     //接收消息
                     Thread th = new Thread(ReceiveMsg);
                     th.IsBackground = true;
                     th.Start(tSocket);
                 }
                 catch (Exception ex)
                 {
                     ShowMsg(ex.Message);
                     break;
                 }
             }
         }
         //接收消息
         void ReceiveMsg(object o)
         {
             Socket client = o as Socket;
             while (true)
             {
                 //接收客户端发送过来的数据
                 try
                 {
                     //定义byte数组存放从客户端接收过来的数据
                     byte[] buffer = new byte[1024 * 1024];
                     //将接收过来的数据放到buffer中，并返回实际接受数据的长度
                     int n = client.Receive(buffer);
                     //将字节转换成字符串
                     string words = Encoding.UTF8.GetString(buffer, 0, n);
                     ShowMsg(client.RemoteEndPoint.ToString() + ":" + words);
                 }
                 catch (Exception ex)
                 {
                    ShowMsg(ex.Message);
                     break;
                 }
             }
         }
         void ShowMsg(string msg)
         {
             txtLog.AppendText(msg+"\r\n");
         }
         private void Form1_FormClosing(object sender, FormClosingEventArgs e)
         {
             //主窗体关闭时关闭子线程
         }
         //给客户端发送消息
         private void btnSend_Click(object sender, EventArgs e)
         {
             try
             {
                 ShowMsg(txtMsg.Text);
                 string ip = cboIpPort.Text;
                 byte[] buffer = Encoding.UTF8.GetBytes(txtMsg.Text);
                 dic[ip].Send(buffer);
                 // client.Send(buffer);
             }
             catch (Exception ex)
             {
                ShowMsg(ex.Message);
             }
         }

 Socket client = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
         private void btnConnection_Click(object sender, EventArgs e)
         {
             //连接到的目标IP
             IPAddress ip = IPAddress.Parse(txtIP.Text);
            //IPAddress ip = IPAddress.Any;
            //连接到目标IP的哪个应用(端口号！)
            IPEndPoint point=new IPEndPoint(ip,int.Parse(txtPort.Text));
            try
            {
                //连接到服务器
                client.Connect(point);
                ShowMsg("连接成功");
                ShowMsg("服务器" + client.RemoteEndPoint.ToString());
                ShowMsg("客户端:" + client.LocalEndPoint.ToString());
                //连接成功后，就可以接收服务器发送的信息了
                Thread th=new Thread(ReceiveMsg);
                th.IsBackground = true;
                th.Start();
            }
            catch (Exception ex)
            {
                ShowMsg(ex.Message);
            }
        }
        //接收服务器的消息
        void ReceiveMsg()
        {
            while (true)
            {
                try
                {
                    byte[] buffer = new byte[1024 * 1024];
                    int n = client.Receive(buffer);
                    string s = Encoding.UTF8.GetString(buffer, 0, n);
                    ShowMsg(client.RemoteEndPoint.ToString() + ":" + s);
                }
                catch (Exception ex)
                {
                    ShowMsg(ex.Message);
                    break;
                }
            }
        }
        void ShowMsg(string msg)
        {
            txtInfo.AppendText(msg+"\r\n");
        }
         private void btnSend_Click(object sender, EventArgs e)
         {
             //客户端给服务器发消息
             if (client!=null)
             {
                 try
                 {
                    ShowMsg(txtMsg.Text);
                     byte[] buffer = Encoding.UTF8.GetBytes(txtMsg.Text);
                     client.Send(buffer);
                 }
                 catch (Exception ex)
                 {
                    ShowMsg(ex.Message);
                 }
             }
         }
         private void ClientForm_Load(object sender, EventArgs e)
         {
             Control.CheckForIllegalCrossThreadCalls = false;
         }