初学UDP，点击发送没有反应

Question

using System;
using System.Text;
using System.Windows.Forms;
using System.Net;
using System.Net.Sockets;
using System.Threading;

namespace UDP
{
public partial class Form1 : Form
{

    private IPEndPoint ipLocalPoint;
    private EndPoint RemotePoint;
    private Socket mySocket;
    private bool RunningFlag = false;

    public Form1()
    {
        InitializeComponent();

        int port;
        IPAddress ip;
        //得到本机IP，设置UDP端口号     
        ip = getValidIP(tbLocalIP.Text);
        port = getValidPort(tbLocalPort.Text);
        ipLocalPoint = new IPEndPoint(ip, port);

        //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  
        ip = getValidIP(tbRemoteIP.Text);
        port = getValidPort(tbRemotePort.Text);
        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();
    }

    //private string getIPAddress()
    //{
    //     //获得本机局域网IP地址  
    //    IPAddress[] AddressList = Dns.GetHostEntry(Dns.GetHostName()).AddressList;
    //    if (AddressList.Length < 1)
    //    {
    //        return "";
    //    }
    //    return AddressList[0].ToString();
    //}

    private int getValidPort(string port)
    {
        int lport;
        //测试端口号是否有效  
        try
        {
            //是否为空  
            if (port == "")
            {
                throw new ArgumentException("端口号无效，不能启动DUP");
            }
            lport = System.Convert.ToInt32(port);
        }
        catch (Exception e)
        {
            //ArgumentException,   
            //FormatException,   
            //OverflowException  
            Console.WriteLine("无效的端口号：" + e.ToString());
            this.tbMsg.AppendText("无效的端口号：" + e.ToString() + "\n");
            return -1;
        }
        return lport;
    }


    private IPAddress getValidIP(string ip)
    {
        IPAddress lip = null;
        //测试IP是否有效  
        try
        {
            //是否为空  
            if (!IPAddress.TryParse(ip, out lip))
            {
                throw new ArgumentException(
                    "IP无效，不能启动DUP");
            }
        }
        catch (Exception e)
        {
            //ArgumentException,   
            //FormatException,   
            //OverflowException  
            Console.WriteLine("无效的IP：" + e.ToString());
            this.tbMsg.AppendText("无效的IP：" + e.ToString() + "\n");
            return null;
        }
        return lip;
    }

    //定义一个委托
    //在 WinForm开发过程中经常会用到线程，有时候还往往需要在线程中访问线程外的控件;
    //比如：设置textbox的Text属性等等。如果直接设置程序必定会报出：从不是创建控件的线程访问它，这个异常。
    //通常我们可以采用两种方法来解决。一是通过设置control的属性。二是通过delegate,而通过delegate也有两种方式，一种是常用的方式，另一种就是匿名方式。下面加以说明.
    public delegate void MyInvoke(string strRecv);
    private void ReceiveHandle()
    {
        //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 });

        }
    }

    private void btSend_Click(object sender, EventArgs e)
    {
        string msg = tbSendMsg.Text;
        //发送UDP数据包  
        byte[] data = Encoding.Default.GetBytes(msg);
        mySocket.SendTo(data, data.Length, SocketFlags.None, RemotePoint);
    }

    private void UpdateMsgTextBox(string msg)
    {
        //接收数据显示  
        this.tbMsg.AppendText(msg + "\n");
    }
}

}

Answer 1