开篇

本人因为对于网络编程的喜爱，经常性的使用c#编写各类服务器(e.g TCP服务器，UDP服务器)，但是基本上都是搞着玩，网上也有很多讲c#网络编程的文章，当然我也参考了很多作者写的文章。看了这篇文章以后再也不用导出找资料了。微笑
本系列文章会依次介绍使用Socket实现的异步TCP服务器、同步TCP服务器、异步UDP服务器、同步UDP服务器 and 使用TcpListener和UdpClient实现的异步TCP服务器、同步TCP服务器、异步UDP服务器、同步UDP服务器。

Socket异步TCP服务器

相信搞过网络编程的人来说这个TCP一点也不陌生吧，在C#中微软已经帮我们封装过了一个TcpListener和TcpClient这两个类了，实现了对于套接字的封装，但是呢实际上还是不怎么好用，所以我们用Socket来实现一个异步的TCP服务器。
在本文中我只给出服务器端代码，客户端代码自己可以找找别处，毕竟我只是为了写出一个好的服务器端
下面是代码
[csharp] view plain copy
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net.Sockets;
using System.Net;

namespace NetFrame.Net.TCP.Sock.Asynchronous
{

/// <summary>  
/// Socket实现的异步TCP服务器  
/// </summary>  
public class AsyncSocketTCPServer : IDisposable  
{  
    #region Fields  
    /// <summary>  
    /// 服务器程序允许的最大客户端连接数  
    /// </summary>  
    private int _maxClient;  

    /// <summary>  
    /// 当前的连接的客户端数  
    /// </summary>  
    private int _clientCount;  

    /// <summary>  
    /// 服务器使用的异步socket  
    /// </summary>  
    private Socket _serverSock;  

    /// <summary>  
    /// 客户端会话列表  
    /// </summary>  
    private List<AsyncSocketState> _clients;  

    private bool disposed = false;  

    #endregion  

    #region Properties  

    /// <summary>  
    /// 服务器是否正在运行  
    /// </summary>  
    public bool IsRunning { get; private set; }  
    /// <summary>  
    /// 监听的IP地址  
    /// </summary>  
    public IPAddress Address { get; private set; }  
    /// <summary>  
    /// 监听的端口  
    /// </summary>  
    public int Port { get; private set; }  
    /// <summary>  
    /// 通信使用的编码  
    /// </summary>  
    public Encoding Encoding { get; set; }  

    #endregion  

    #region 构造函数  

    /// <summary>  
    /// 异步Socket TCP服务器  
    /// </summary>  
    /// <param name="listenPort">监听的端口</param>  
    public AsyncSocketTCPServer(int listenPort)  
        : this(IPAddress.Any, listenPort,1024)  
    {  
    }  

    /// <summary>  
    /// 异步Socket TCP服务器  
    /// </summary>  
    /// <param name="localEP">监听的终结点</param>  
    public AsyncSocketTCPServer(IPEndPoint localEP)  
        : this(localEP.Address, localEP.Port,1024)  
    {  
    }  

    /// <summary>  
    /// 异步Socket TCP服务器  
    /// </summary>  
    /// <param name="localIPAddress">监听的IP地址</param>  
    /// <param name="listenPort">监听的端口</param>  
    /// <param name="maxClient">最大客户端数量</param>  
    public AsyncSocketTCPServer(IPAddress localIPAddress, int listenPort,int maxClient)  
    {  
        this.Address = localIPAddress;  
        this.Port = listenPort;  
        this.Encoding = Encoding.Default;  

        _maxClient = maxClient;  
        _clients = new List<AsyncSocketState>();  
        _serverSock = new Socket(localIPAddress.AddressFamily, SocketType.Stream, ProtocolType.Tcp);  
    }  

    #endregion  

    #region Method  

    /// <summary>  
    /// 启动服务器  
    /// </summary>  
    public void Start()  
    {  
        if (!IsRunning)  
        {  
            IsRunning = true;  
            _serverSock.Bind(new IPEndPoint(this.Address, this.Port));  
            _serverSock.Listen(1024);  
            _serverSock.BeginAccept(new AsyncCallback(HandleAcceptConnected), _serverSock);  
        }  
    }  

    /// <summary>  
    /// 启动服务器  
    /// </summary>  
    /// <param name="backlog">  
    /// 服务器所允许的挂起连接序列的最大长度  
    /// </param>  
    public void Start(int backlog)  
    {  
        if (!IsRunning)  
        {  
            IsRunning = true;  
            _serverSock.Bind(new IPEndPoint(this.Address, this.Port));  
            _serverSock.Listen(backlog);  
            _serverSock.BeginAccept(new AsyncCallback(HandleAcceptConnected), _serverSock);  
        }  
    }  

    /// <summary>  
    /// 停止服务器  
    /// </summary>  
    public void Stop()  
    {  
        if (IsRunning)  
        {  
            IsRunning = false;  
            _serverSock.Close();  
            //TODO 关闭对所有客户端的连接  

        }  
    }  

    /// <summary>  
    /// 处理客户端连接  
    /// </summary>  
    /// <param name="ar"></param>  
    private void HandleAcceptConnected(IAsyncResult ar)  
    {  
        if (IsRunning)  
        {  
            Socket server = (Socket)ar.AsyncState;  
            Socket client = server.EndAccept(ar);  

            //检查是否达到最大的允许的客户端数目  
            if (_clientCount >= _maxClient)  
            {  
                //C-TODO 触发事件  
                RaiseOtherException(null);  
            }  
            else  
            {  
                AsyncSocketState state = new AsyncSocketState(client);  
                lock (_clients)  
                {  
                    _clients.Add(state);  
                    _clientCount++;  
                    RaiseClientConnected(state); //触发客户端连接事件  
                }  
                state.RecvDataBuffer = new byte[client.ReceiveBufferSize];  
                //开始接受来自该客户端的数据  
                client.BeginReceive(state.RecvDataBuffer, 0, state.RecvDataBuffer.Length, SocketFlags.None,  
                 new AsyncCallback(HandleDataReceived), state);  
            }  
            //接受下一个请求  
            server.BeginAccept(new AsyncCallback(HandleAcceptConnected), ar.AsyncState);  
        }  
    }  
    /// <summary>  
    /// 处理客户端数据  
    /// </summary>  
    /// <param name="ar"></param>  
    private void HandleDataReceived(IAsyncResult ar)  
    {  
        if (IsRunning)  
        {  
            AsyncSocketState state = (AsyncSocketState)ar.AsyncState;  
            Socket client = state.ClientSocket;  
            try  
            {  
                //如果两次开始了异步的接收,所以当客户端退出的时候  
                //会两次执行EndReceive  
                int recv = client.EndReceive(ar);  
                if (recv == 0)  
                {  
                    //C- TODO 触发事件 (关闭客户端)  
                    Close(state);  
                    RaiseNetError(state);  
                    return;  
                }  
                //TODO 处理已经读取的数据 ps:数据在state的RecvDataBuffer中  

                //C- TODO 触发数据接收事件  
                RaiseDataReceived(state);  
            }  
            catch (SocketException)  
            {  
                //C- TODO 异常处理  
                RaiseNetError(state);  
            }  
            finally  
            {  
                //继续接收来自来客户端的数据  
                client.BeginReceive(state.RecvDataBuffer, 0, state.RecvDataBuffer.Length, SocketFlags.None,  
                 new AsyncCallback(HandleDataReceived), state);  
            }  
        }  
    }  

    /// <summary>  
    /// 发送数据  
    /// </summary>  
    /// <param name="state">接收数据的客户端会话</param>  
    /// <param name="data">数据报文</param>  
    public void Send(AsyncSocketState state, byte[] data)  
    {  
        RaisePrepareSend(state);  
        Send(state.ClientSocket, data);  
    }  

    /// <summary>  
    /// 异步发送数据至指定的客户端  
    /// </summary>  
    /// <param name="client">客户端</param>  
    /// <param name="data">报文</param>  
    public void Send(Socket client, byte[] data)  
    {  
        if (!IsRunning)  
            throw new InvalidProgramException("This TCP Scoket server has not been started.");  

        if (client == null)  
            throw new ArgumentNullException("client");  

        if (data == null)  
            throw new ArgumentNullException("data");  
        client.BeginSend(data, 0, data.Length, SocketFlags.None,  
         new AsyncCallback(SendDataEnd), client);  
    }  

    /// <summary>  
    /// 发送数据完成处理函数  
    /// </summary>  
    /// <param name="ar">目标客户端Socket</param>  
    private void SendDataEnd(IAsyncResult ar)  
    {  
        ((Socket)ar.AsyncState).EndSend(ar);  
        RaiseCompletedSend(null);  
    }  
    #endregion  

    #region 事件  

    /// <summary>  
    /// 与客户端的连接已建立事件  
    /// </summary>  
    public event EventHandler<AsyncSocketEventArgs> ClientConnected;  
    /// <summary>  
    /// 与客户端的连接已断开事件  
    /// </summary>  
    public event EventHandler<AsyncSocketEventArgs> ClientDisconnected;  

    /// <summary>  
    /// 触发客户端连接事件  
    /// </summary>  
    /// <param name="state"></param>  
    private void RaiseClientConnected(AsyncSocketState state)  
    {  
        if (ClientConnected != null)  
        {  
            ClientConnected(this, new AsyncSocketEventArgs(state));  
        }  
    }  
    /// <summary>  
    /// 触发客户端连接断开事件  
    /// </summary>  
    /// <param name="client"></param>  
    private void RaiseClientDisconnected(Socket client)  
    {  
        if (ClientDisconnected != null)  
        {  
            ClientDisconnected(this, new AsyncSocketEventArgs("连接断开"));  
        }  
    }  

    /// <summary>  
    /// 接收到数据事件  
    /// </summary>  
    public event EventHandler<AsyncSocketEventArgs> DataReceived;  

    private void RaiseDataReceived(AsyncSocketState state)  
    {  
        if (DataReceived != null)  
        {  
            DataReceived(this, new AsyncSocketEventArgs(state));  
        }  
    }  

    /// <summary>  
    /// 发送数据前的事件  
    /// </summary>  
    public event EventHandler<AsyncSocketEventArgs> PrepareSend;  

    /// <summary>  
    /// 触发发送数据前的事件  
    /// </summary>  
    /// <param name="state"></param>  
    private void RaisePrepareSend(AsyncSocketState state)  
    {  
        if (PrepareSend != null)  
        {  
            PrepareSend(this, new AsyncSocketEventArgs(state));  
        }  
    }  

    /// <summary>  
    /// 数据发送完毕事件  
    /// </summary>  
    public event EventHandler<AsyncSocketEventArgs> CompletedSend;  
      
    /// <summary>  
    /// 触发数据发送完毕的事件  
    /// </summary>  
    /// <param name="state"></param>  
    private void RaiseCompletedSend(AsyncSocketState state)  
    {  
        if (CompletedSend != null)  
        {  
            CompletedSend(this, new AsyncSocketEventArgs(state));  
        }  
    }  

    /// <summary>  
    /// 网络错误事件  
    /// </summary>  
    public event EventHandler<AsyncSocketEventArgs> NetError;  
    /// <summary>  
    /// 触发网络错误事件  
    /// </summary>  
    /// <param name="state"></param>  
    private void RaiseNetError(AsyncSocketState state)  
    {  
        if (NetError != null)  
        {  
            NetError(this, new AsyncSocketEventArgs(state));  
        }  
    }  

    /// <summary>  
    /// 异常事件  
    /// </summary>  
    public event EventHandler<AsyncSocketEventArgs> OtherException;  
    /// <summary>  
    /// 触发异常事件  
    /// </summary>  
    /// <param name="state"></param>  
    private void RaiseOtherException(AsyncSocketState state, string descrip)  
    {  
        if (OtherException != null)  
        {  
            OtherException(this, new AsyncSocketEventArgs(descrip, state));  
        }  
    }  
    private void RaiseOtherException(AsyncSocketState state)  
    {  
        RaiseOtherException(state, "");  
    }  
    #endregion  

    #region Close  
    /// <summary>  
    /// 关闭一个与客户端之间的会话  
    /// </summary>  
    /// <param name="state">需要关闭的客户端会话对象</param>  
    public void Close(AsyncSocketState state)  
    {  
        if (state != null)  
        {  
            state.Datagram = null;  
            state.RecvDataBuffer = null;  

            _clients.Remove(state);  
            _clientCount--;  
            //TODO 触发关闭事件  
            state.Close();  
        }  
    }  
    /// <summary>  
    /// 关闭所有的客户端会话,与所有的客户端连接会断开  
    /// </summary>  
    public void CloseAllClient()  
    {  
        foreach (AsyncSocketState client in _clients)  
        {  
            Close(client);  
        }  
        _clientCount = 0;  
        _clients.Clear();  
    }  
    #endregion  

    #region 释放  
    /// <summary>  
    /// Performs application-defined tasks associated with freeing,   
    /// releasing, or resetting unmanaged resources.  
    /// </summary>  
    public void Dispose()  
    {  
        Dispose(true);  
        GC.SuppressFinalize(this);  
    }  

    /// <summary>  
    /// Releases unmanaged and - optionally - managed resources  
    /// </summary>  
    /// <param name="disposing"><c>true</c> to release   
    /// both managed and unmanaged resources; <c>false</c>   
    /// to release only unmanaged resources.</param>  
    protected virtual void Dispose(bool disposing)  
    {  
        if (!this.disposed)  
        {  
            if (disposing)  
            {  
                try  
                {  
                    Stop();  
                    if (_serverSock != null)  
                    {  
                        _serverSock = null;  
                    }  
                }  
                catch (SocketException)  
                {  
                    //TODO  
                    RaiseOtherException(null);  
                }  
            }  
            disposed = true;  
        }  
    }  
    #endregion  
}  

}

事件参数类
[csharp] view plain copy
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace NetFrame.Net.TCP.Sock.Asynchronous
{

/// <summary>  
/// 异步Socket TCP事件参数类  
/// </summary>  
public class AsyncSocketEventArgs:EventArgs  
{  
    /// <summary>  
    /// 提示信息  
    /// </summary>  
    public string _msg;  

    /// <summary>  
    /// 客户端状态封装类  
    /// </summary>  
    public AsyncSocketState _state;  

    /// <summary>  
    /// 是否已经处理过了  
    /// </summary>  
    public bool IsHandled { get; set; }  

    public AsyncSocketEventArgs(string msg)  
    {  
        this._msg = msg;  
        IsHandled = false;  
    }  
    public AsyncSocketEventArgs(AsyncSocketState state)  
    {  
        this._state = state;  
        IsHandled = false;  
    }  
    public AsyncSocketEventArgs(string msg, AsyncSocketState state)  
    {  
        this._msg = msg;  
        this._state = state;  
        IsHandled = false;  
    }  
}  

}

用户状态封装
[csharp] view plain copy
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net.Sockets;

namespace NetFrame.Net.TCP.Sock.Asynchronous
{

/// <summary>  
/// 异步SOCKET TCP 中用来存储客户端状态信息的类  
/// </summary>  
public class AsyncSocketState  
{  
    #region 字段  
    /// <summary>  
    /// 接收数据缓冲区  
    /// </summary>  
    private byte[] _recvBuffer;  

    /// <summary>  
    /// 客户端发送到服务器的报文  
    /// 注意:在有些情况下报文可能只是报文的片断而不完整  
    /// </summary>  
    private string _datagram;  

    /// <summary>  
    /// 客户端的Socket  
    /// </summary>  
    private Socket _clientSock;  

    #endregion  

    #region 属性  

    /// <summary>  
    /// 接收数据缓冲区   
    /// </summary>  
    public byte[] RecvDataBuffer  
    {  
        get  
        {  
            return _recvBuffer;  
        }  
        set  
        {  
            _recvBuffer = value;  
        }  
    }  

    /// <summary>  
    /// 存取会话的报文  
    /// </summary>  
    public string Datagram  
    {  
        get  
        {  
            return _datagram;  
        }  
        set  
        {  
            _datagram = value;  
        }  
    }  

    /// <summary>  
    /// 获得与客户端会话关联的Socket对象  
    /// </summary>  
    public Socket ClientSocket  
    {  
        get  
        {  
            return _clientSock;  

        }  
    }  

    #endregion  

    /// <summary>  
    /// 构造函数  
    /// </summary>  
    /// <param name="cliSock">会话使用的Socket连接</param>  
    public AsyncSocketState(Socket cliSock)  
    {  
        _clientSock = cliSock;  
    }  

    /// <summary>  
    /// 初始化数据缓冲区  
    /// </summary>  
    public void InitBuffer()  
    {  
        if (_recvBuffer == null&&_clientSock!=null)  
        {  
            _recvBuffer=new byte[_clientSock.ReceiveBufferSize];  
        }  
    }  

    /// <summary>  
    /// 关闭会话  
    /// </summary>  
    public void Close()  
    {  

        //关闭数据的接受和发送  
        _clientSock.Shutdown(SocketShutdown.Both);  

        //清理资源  
        _clientSock.Close();  
    }  
}  

}

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