ipLocalPoint = new IPEndPoint(IPAddress.Parse("192.168.31.122"), 5000);

            //定义网络类型，数据连接类型和网络协议UDP 
            mySocket = new Socket
   (AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);

            //绑定网络地址 
            mySocket.Bind(ipLocalPoint);

            //得到客户机IP 
            IPAddress ip = IPAddress.Parse("192.168.31.127");
            int port = 5000;
            IPEndPoint ipep = new IPEndPoint(ip, port);
            RemotePoint = (EndPoint)(ipep);

            //启动一个新的线程，执行方法this.ReceiveHandle， 
            //以便在一个独立的进程中执行数据接收的操作 

            RunningFlag = true;
            Thread thread = new Thread(new ThreadStart(this.ReceiveHandle));
            thread.Start();

  //接收数据处理线程 
            string msg;
            byte[] data = new byte[1024];
            MyInvoke myI = new MyInvoke(UpdateMsgTextBox);
            while (RunningFlag)
            {

                if (mySocket == null || mySocket.Available < 1)
                {
                    Thread.Sleep(200);
                    continue;
                }
                //跨线程调用控件 
                //接收UDP数据报，引用参数RemotePoint获得源地址 
                int rlen = mySocket.ReceiveFrom(data, ref RemotePoint);
                msg = Encoding.Default.GetString(data, 0, rlen);
                tbMsg.BeginInvoke
                    (myI, new object[] { RemotePoint.ToString() + " : " + msg });

            }

    string msg;
            msg = tbSendMsg.Text;
            //发送UDP数据包 
            byte[] data = Encoding.Default.GetBytes(msg);
            mySocket.SendTo(data, data.Length, SocketFlags.None, RemotePoint);

     //接收数据显示 
            this.tbMsg.AppendText(msg + "\n");