c# 使用UDPClient实现异步通信

下载：http://download.csdn.net/download/cdtaixf/7239105

server：

using System;
using System.Text;
using System.Net;
using System.Net.Sockets;

namespace AsyncServer
{
class Program
{
private static IPEndPoint epServer;
private static IPEndPoint epClient;
private static UdpClient server;

static void Main(string[] args)
{
epServer = new IPEndPoint(IPAddress.Any, 11000); //设置服务器端口，IP是本程序所在PC的内网IP
epClient = new IPEndPoint(IPAddress.Any, 0); //设置客户端，任意IP，任意端口号
server = new UdpClient(epServer); //绑定设置的服务器端口和IP
Console.WriteLine("listening...");
while (true) {
//下面三行代码经过修改，原代码如下
//server.BeginReceive(new AsyncCallback(ReceiveCallback), null);
//该代码会被挂起，接收到一个消息时启动一个线程，该线程启动函数是：ReceiveCallback，在该函数中
//会修改epClient的值，但程序会继续向下执行，执行到server.BeginSend时，发现epClient是无效的，报异常
//所以改为如下代码，可以正常运行
IAsyncResult iar = server.BeginReceive(null, null);
byte[] receiveData = server.EndReceive(iar, ref epClient);
Console.WriteLine("Received a message from [{0}]: {1}", epClient, Encoding.ASCII.GetString(receiveData));
//以下是发送消息回客户端
string strSend = "hello " + epClient.ToString();
byte[] sendData = Encoding.ASCII.GetBytes(strSend);
//下面一行代码，将启动一个线程，该线程启动函数：SendCallback，该函数结束挂起的异步发送
server.BeginSend(sendData, sendData.Length, epClient, new AsyncCallback(SendCallback), null);
}
}
//此函数未被使用，如需使用，可以借鉴
private static void ReceiveCallback(IAsyncResult iar)
{
byte[] receiveData = server.EndReceive(iar, ref epClient);
Console.WriteLine("Received a message from [{0}]: {1}", epClient, Encoding.ASCII.GetString(receiveData));
}

private static void SendCallback(IAsyncResult iar)
{
int sendCount = server.EndSend(iar);
if (sendCount == 0)
{ Console.WriteLine("Send a message failure..."); }
}
}
}


client

using System;
using System.Text;
using System.Net;
using System.Net.Sockets;

namespace AsyncClient
{
class Program
{
private static IPEndPoint epServer;
private static UdpClient local;

static void Main(string[] args)
{
//设置服务器端IP和端口
epServer = new IPEndPoint(IPAddress.Parse("192.168.1.140"), 11000);
local = new UdpClient(9001); //绑定本机IP和端口，9001
while (true) {
string strSend = Console.ReadLine();
if (strSend == "exit") break;
byte[] sendData = Encoding.ASCII.GetBytes(strSend);
//开始异步发送，启动一个线程，该线程启动函数是：SendCallback，该函数中结束挂起的异步发送
local.BeginSend(sendData, sendData.Length, epServer, new AsyncCallback(SendCallback), null);
//开始异步接收启动一个线程，该线程启动函数是：ReceiveCallback，该函数中结束挂起的异步接收
local.BeginReceive(new AsyncCallback(ReceiveCallback), null);
}
}

private static void SendCallback(IAsyncResult iar)
{
int sendCount = local.EndSend(iar);
if (sendCount == 0)
{ Console.WriteLine("Send a message failure..."); }
}

private static void ReceiveCallback(IAsyncResult iar)
{
byte[] receiveData = local.EndReceive(iar, ref epServer);
Console.WriteLine("Server: {0}", Encoding.ASCII.GetString(receiveData));
}
}
}