详解C# Socket异步通信实例

TCPServer 

1、使用的通讯通道：socket

2、用到的基本功能：

①Bind,

②Listen,

③BeginAccept

④EndAccept

⑤BeginReceive 

⑥EndReceive

3、函数参数说明

Socket listener = new Socket(AddressFamily.InterNetwork,

SocketType.Stream, ProtocolType.Tcp);

新建socket所使用的参数均为系统预定义的量，直接选取使用。

listener.Bind(localEndPoint);

localEndPoint 表示一个定义完整的终端，包括IP和端口信息。

//new IPEndPoint(IPAddress,port)

//IPAdress.Parse("192.168.1.3")

listener.Listen(100);

监听

 listener.BeginAccept(

new AsyncCallback(AcceptCallback),

listener);

AsyncCallback(AcceptCallback),一旦连接上后的回调函数为AcceptCallback。当系统调用这个函数时，自动赋予的输入参数为IAsyncResoult类型变量ar。

 listener，连接行为的容器。

Socket handler = listener.EndAccept(ar);

完成连接，返回此时的socket通道。

handler.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,

new AsyncCallback(ReadCallback), state);

接收的字节，0，字节长度，0，接收时调用的回调函数，接收行为的容器。

========

容器的结构类型为：

public class StateObject
{
 // Client socket.
 public Socket workSocket = null;
 // Size of receive buffer.
 public const int BufferSize = 1024;
 // Receive buffer.
 public byte[] buffer = new byte[BufferSize];
 // Received data string.
 public StringBuilder sb = new StringBuilder();
}

容器至少为一个socket类型。

===============

// Read data from the client socket.

int bytesRead = handler.EndReceive(ar);

完成一次连接。数据存储在state.buffer里，bytesRead为读取的长度。

handler.BeginSend(byteData, 0, byteData.Length, 0,

new AsyncCallback(SendCallback), handler);

发送数据byteData，回调函数SendCallback。容器handler

int bytesSent = handler.EndSend(ar);

发送完毕，bytesSent发送字节数。

4 程序结构

主程序：

   byte[] bytes = new Byte[1024];
   IPAddress ipAddress = IPAddress.Parse("192.168.1.104");
   IPEndPoint localEndPoint = new IPEndPoint(ipAddress, 11000);

// 生成一个TCP的socket
   Socket listener = new Socket(AddressFamily.InterNetwork,
     SocketType.Stream, ProtocolType.Tcp);

listener.Bind(localEndPoint);
   listener.Listen(100);

while (true)
   {

// Set the event to nonsignaled state.
     allDone.Reset();

//开启异步监听socket
     Console.WriteLine("Waiting for a connection");
     listener.BeginAccept(
          new AsyncCallback(AcceptCallback),
          listener);

// 让程序等待，直到连接任务完成。在AcceptCallback里的适当位置放置allDone.Set()语句.
     allDone.WaitOne();
     }

Console.WriteLine("\nPress ENTER to continue");
 Console.Read();

连接行为回调函数AcceptCallback：

 public static void AcceptCallback(IAsyncResult ar)

{

//添加此命令，让主线程继续.

allDone.Set();

// 获取客户请求的socket

Socket listener = (Socket)ar.AsyncState;

Socket handler = listener.EndAccept(ar);

// 造一个容器，并用于接收命令.

StateObject state = new StateObject();

state.workSocket = handler;

handler.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,

new AsyncCallback(ReadCallback), state);

}

读取行为的回调函数ReadCallback:

 public static void ReadCallback(IAsyncResult ar)

{

String content = String.Empty;

// 从异步state对象中获取state和socket对象.

StateObject state = (StateObject)ar.AsyncState;

Socket handler = state.workSocket;

// 从客户socket读取数据.

int bytesRead = handler.EndReceive(ar);

if (bytesRead > 0)

{

// 如果接收到数据，则存起来

state.sb.Append(Encoding.ASCII.GetString(state.buffer, 0, bytesRead));

// 检查是否有结束标记，如果没有则继续读取

content = state.sb.ToString();

if (content.IndexOf("<EOF>") > -1)

{

//所有数据读取完毕.

Console.WriteLine("Read {0} bytes from socket. \n Data : {1}",

content.Length, content);

// 给客户端响应.

Send(handler, content);

}

else

{

// 接收未完成，继续接收.

handler.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,

new AsyncCallback(ReadCallback), state);

}

}

}

发送消息给客户端：

private static void Send(Socket handler, String data)

{

// 消息格式转换.

byte[] byteData = Encoding.ASCII.GetBytes(data);

// 开始发送数据给远程目标.

handler.BeginSend(byteData, 0, byteData.Length, 0,

new AsyncCallback(SendCallback), handler);

}

private static void SendCallback(IAsyncResult ar)

{

// 从state对象获取socket.

Socket handler = (Socket)ar.AsyncState;

//完成数据发送

int bytesSent = handler.EndSend(ar);

Console.WriteLine("Sent {0} bytes to client.", bytesSent);

handler.Shutdown(SocketShutdown.Both);

handler.Close();

}

在各种行为的回调函数中，所对应的socket都从输入参数的AsyncState属性获得。使用（Socket）或者（StateObject）进行强制转换。BeginReceive函数使用的容器为state，因为它需要存放传送的数据。

而其余接收或发送函数的容器为socket也可。

完整代码

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

// State object for reading client data asynchronously
 public class StateObject
 {
  // Client socket.
  public Socket workSocket = null;
  // Size of receive buffer.
  public const int BufferSize = ;
  // Receive buffer.
  public byte[] buffer = new byte[BufferSize];
  // Received data string.
  public StringBuilder sb = new StringBuilder();
}

public class AsynchronousSocketListener
{
  // Thread signal.
  public static ManualResetEvent allDone = new ManualResetEvent(false);

public AsynchronousSocketListener()
  {
  }

public static void StartListening()
  {
    // Data buffer for incoming data.
    byte[] bytes = new Byte[];

// Establish the local endpoint for the socket.
    // The DNS name of the computer
    // running the listener is "host.contoso.com".
    //IPHostEntry ipHostInfo = Dns.Resolve(Dns.GetHostName());
    IPAddress ipAddress = IPAddress.Parse("...");

IPEndPoint localEndPoint = new IPEndPoint(ipAddress, );

// Create a TCP/IP socket.
    Socket listener = new Socket(AddressFamily.InterNetwork,
      SocketType.Stream, ProtocolType.Tcp);

// Bind the socket to the local endpoint and listen for incoming connections.
    try
    {
      listener.Bind(localEndPoint);
      listener.Listen();
      while (true)
      {
        // Set the event to nonsignaled state.
        allDone.Reset();

// Start an asynchronous socket to listen for connections.
        Console.WriteLine("Waiting for a connection");
        listener.BeginAccept(
          new AsyncCallback(AcceptCallback),
          listener);

// Wait until a connection is made before continuing.
        allDone.WaitOne();
      }
    }
    catch (Exception e)
    {
      Console.WriteLine(e.ToString());
    }

Console.WriteLine("\nPress ENTER to continue");
    Console.Read();
  }

public static void AcceptCallback(IAsyncResult ar)
  {
    // Signal the main thread to continue.
    allDone.Set();

// Get the socket that handles the client request.
    Socket listener = (Socket)ar.AsyncState;
    Socket handler = listener.EndAccept(ar);

// Create the state object.
    StateObject state = new StateObject();
    state.workSocket = handler;
    handler.BeginReceive(state.buffer, , StateObject.BufferSize, , new AsyncCallback(ReadCallback), state);
  }

public static void ReadCallback(IAsyncResult ar)
  {
    String content = String.Empty;

// Retrieve the state object and the handler socket
    // from the asynchronous state object.
    StateObject state = (StateObject)ar.AsyncState;
    Socket handler = state.workSocket;

// Read data from the client socket.
    int bytesRead = handler.EndReceive(ar);

if (bytesRead > )
    {
      // There might be more data, so store the data received so far.
      state.sb.Append(Encoding.ASCII.GetString(
        state.buffer, , bytesRead));

// Check for end-of-file tag. If it is not there, read
      // more data.
      content = state.sb.ToString();
      if (content.IndexOf("<EOF>") > -)
      {
        // All the data has been read from the
        // client. Display it on the console.
        Console.WriteLine("Read {} bytes from socket. \n Data : {}",content.Length, content);

// Echo the data back to the client.
        Send(handler, content);
      }
      else
      {
        // Not all data received. Get more.
        handler.BeginReceive(state.buffer, , StateObject.BufferSize, , new AsyncCallback(ReadCallback), state);
      }
    }
  }

private static void Send(Socket handler, String data)
  {
    // Convert the string data to byte data using ASCII encoding.
    byte[] byteData = Encoding.ASCII.GetBytes(data);

// Begin sending the data to the remote device.
    handler.BeginSend(byteData, , byteData.Length, ,
      new AsyncCallback(SendCallback), handler);
  }

private static void SendCallback(IAsyncResult ar)

{
    try
    {
      // Retrieve the socket from the state object.
      Socket handler = (Socket)ar.AsyncState;

// Complete sending the data to the remote device.
      int bytesSent = handler.EndSend(ar);
      Console.WriteLine("Sent {} bytes to client.", bytesSent);
      handler.Shutdown(SocketShutdown.Both);
      handler.Close();
    }

catch (Exception e)

{
      Console.WriteLine(e.ToString());
    }
  }

public static int Main(String[] args)

{
    StartListening();
    return ;
  }

}

来源：http://www.cnblogs.com/kingmoon/archive/2011/04/29/2032452.html