using System;
using
using
using System.Text;
namespace UdpClientServer
{
    class class1
    {
        static void Main()
        {
            StarListener();
            Console.ReadLine();
        }
        private static void StarListener()
        {
            UdpClient udpServer=new UdpClient(8000);
            IPEndPoint myHost=null;
            {
                while(true)
                {
                    try
                    Console.WriteLine("等待接受...");
                    byte[]getBytes=udpServer.Receive(ref myHost);
                    string getString=Encoding.Unicode.GetString(getBytes,0,getBytes.Length);
                    Console.WriteLine("接受信息:{0}",getString);
                    if(getString=="quite")break;
                    string sendString="你好，多保重！"；
                    Console,WriteLine("发送消息:{0}",sendString);
                    byte[]sendBytes=Encoding.Unicode.GetBytes(sendString);
                    udpServer.Send(sendBytes,sendBytes.Length,"127.0.0.1",8001);
                }
                udpServer.Close();
                Console.WriteLine("对方已经退出，请按回车键退出。");
            }
            catch(Exception err)
            {
                Console.WriteLine(err.ToString());
            }
        }
    }
}

一个简单的UDP服务器，监听本地8000端口，并接受来自客户端的消息，然后回复一个固定的消息：“你好，多保重！”。运行程序，并在命令行中输入“quite”来停止程序。