(转)C# Socket异步通信

本文转载自：http://www.cnblogs.com/llllll/archive/2009/05/13/1455703.html

服务器端

TCPServer

1、使用的通讯通道：socket

2、用到的基本功能：

Bind,

Listen,

BeginAccept

EndAccept

BeginReceive

EndReceive

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("") > -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 = 1024;
    // 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[1024];

        // 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("192.168.1.104");
        IPEndPoint localEndPoint = new IPEndPoint(ipAddress, 11000);

        // 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(100);

            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, 0, StateObject.BufferSize, 0,
            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 > 0)
        {
            // There  might be more data, so store the data received so far.
            state.sb.Append(Encoding.ASCII.GetString(
                state.buffer, 0, bytesRead));

            // Check for end-of-file tag. If it is not there, read 
            // more data.
            content = state.sb.ToString();
            if (content.IndexOf("") > -1)
            {
                // All the data has been read from the 
                // client. Display it on the console.
                Console.WriteLine("Read {0} bytes from socket. \n Data : {1}",
                    content.Length, content);
                // Echo the data back to the client.
                Send(handler, content);
            }
            else
            {
                // Not all data received. Get more.
                handler.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
                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, 0, byteData.Length, 0,
            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 {0} 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 0;
    }
}