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 ;
   }

 }

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