本文介绍
在.Net中，System.Net.Sockets 命名空间为需要严密控制网络访问的开发人员提供了 Windows Sockets (Winsock) 接口的托管实现。System.Net 命名空间中的所有其他网络访问类都建立在该套接字Socket实现之上，如TCPClient、TCPListener 和 UDPClient 类封装有关创建到 Internet 的 TCP 和 UDP 连接的详细信息；NetworkStream类则提供用于网络访问的基础数据流等，常见的许多Internet服务都可以见到Socket的踪影，如Telnet、Http、Email、Echo等，这些服务尽管通讯协议Protocol的定义不同，但是其基础的传输都是采用的Socket。 其实，Socket可以象流Stream一样被视为一个数据通道，这个通道架设在应用程序端（客户端）和远程服务器端之间，而后，数据的读取（接收）和写入（发送）均针对这个通道来进行。
可见，在应用程序端或者服务器端创建了Socket对象之后，就可以使用Send/SentTo方法将数据发送到连接的Socket,或者使用Receive/ReceiveFrom方法接收来自连接Socket的数据；
针对Socket编程，.NET 框架的 Socket 类是 Winsock32 API 提供的套接字服务的托管代码版本。其中为实现网络编程提供了大量的方法，大多数情况下，Socket 类方法只是将数据封送到它们的本机 Win32 副本中并处理任何必要的安全检查。如果你熟悉Winsock API函数，那么用Socket类编写网络程序会非常容易，当然，如果你不曾接触过，也不会太困难，跟随下面的解说，你会发觉使用Socket类开发windows 网络应用程序原来有规可寻，它们在大多数情况下遵循大致相同的步骤。
本节介绍使用socket来实现一个高性能的异步udp服务器，实际上udp是不分客户机和服务器的，但是我们有的时候和服务器通讯就是使用udp来进行的。
Socket异步UDP服务器
using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Net;using System.Net.Sockets;namespace NetFrame.Net.UDP.Sock.Asynchronous{ /// /// SOCKET实现异步UDP服务器 /// public class AsyncSocketUDPServer { #region Fields /// /// 服务器程序允许的最大客户端连接数 /// private int _maxClient; /// /// 当前的连接的客户端数 /// //private int _clientCount; /// /// 服务器使用的同步socket /// private Socket _serverSock; /// /// 客户端会话列表 /// //private List _clients; private bool disposed = false; /// /// 数据接受缓冲区 /// private byte[] _recvBuffer; #endregion #region Properties /// /// 服务器是否正在运行 /// public bool IsRunning { get; private set; } /// /// 监听的IP地址 /// public IPAddress Address { get; private set; } /// /// 监听的端口 /// public int Port { get; private set; } /// /// 通信使用的编码 /// public Encoding Encoding { get; set; } #endregion #region 构造函数 /// /// 异步Socket UDP服务器 /// /// 监听的端口 public AsyncSocketUDPServer(int listenPort) : this(IPAddress.Any, listenPort,1024) { } /// /// 异步Socket UDP服务器 /// /// 监听的终结点 public AsyncSocketUDPServer(IPEndPoint localEP) : this(localEP.Address, localEP.Port,1024) { } /// /// 异步Socket UDP服务器 /// /// 监听的IP地址 /// 监听的端口 /// 最大客户端数量 public AsyncSocketUDPServer(IPAddress localIPAddress, int listenPort, int maxClient) { this.Address = localIPAddress; this.Port = listenPort; this.Encoding = Encoding.Default; _maxClient = maxClient; //_clients = new List(); _serverSock = new Socket(localIPAddress.AddressFamily, SocketType.Dgram, ProtocolType.Udp); _recvBuffer=new byte[_serverSock.ReceiveBufferSize]; } #endregion #region Method /// /// 启动服务器 /// /// 异步TCP服务器 public void Start() { if (!IsRunning) { IsRunning = true; _serverSock.Bind(new IPEndPoint(this.Address, this.Port)); //_serverSock.Connect(new IPEndPoint(IPAddress.Any, 0)); AsyncSocketUDPState so = new AsyncSocketUDPState(); so.workSocket = _serverSock; _serverSock.BeginReceiveFrom(so.buffer, 0, so.buffer.Length, SocketFlags.None, ref so.remote, new AsyncCallback(ReceiveDataAsync), null); //EndPoint sender = new IPEndPoint(IPAddress.Any, 0); //_serverSock.BeginReceiveFrom(_recvBuffer, 0, _recvBuffer.Length, SocketFlags.None, // ref sender, new AsyncCallback(ReceiveDataAsync), sender); //BeginReceive 和 BeginReceiveFrom的区别是什么 /*_serverSock.BeginReceive(_recvBuffer, 0, _recvBuffer.Length, SocketFlags.None, new AsyncCallback(ReceiveDataAsync), null);*/ } } /// /// 停止服务器 /// public void Stop() { if (IsRunning) { IsRunning = false; _serverSock.Close(); //TODO 关闭对所有客户端的连接 } } /// /// 接收数据的方法 /// /// private void ReceiveDataAsync(IAsyncResult ar) { AsyncSocketUDPState so = ar.AsyncState as AsyncSocketUDPState; //EndPoint sender = new IPEndPoint(IPAddress.Any, 0); int len = -1; try { len = _serverSock.EndReceiveFrom(ar, ref so.remote); //len = _serverSock.EndReceiveFrom(ar, ref sender); //EndReceiveFrom 和 EndReceive区别 //len = _serverSock.EndReceive(ar); //TODO 处理数据 //触发数据收到事件 RaiseDataReceived(so); } catch (Exception) { //TODO 处理异常 RaiseOtherException(so); } finally { if (IsRunning && _serverSock != null) _serverSock.BeginReceiveFrom(so.buffer, 0, so.buffer.Length, SocketFlags.None, ref so.remote, new AsyncCallback(ReceiveDataAsync), so); } } /// /// 发送数据 /// /// /// public void Send(string msg,EndPoint remote) { byte[] data = Encoding.Default.GetBytes(msg); try { RaisePrepareSend(null); _serverSock.BeginSendTo(data, 0, data.Length, SocketFlags.None, remote, new AsyncCallback(SendDataEnd), _serverSock); } catch (Exception) { //TODO 异常处理 RaiseOtherException(null); } } private void SendDataEnd(IAsyncResult ar) { ((Socket)ar.AsyncState).EndSendTo(ar); RaiseCompletedSend(null); } #endregion #region 事件 /// /// 接收到数据事件 /// public event EventHandler DataReceived; private void RaiseDataReceived(AsyncSocketUDPState state) { if (DataReceived != null) { DataReceived(this, new AsyncSocketUDPEventArgs(state)); } } /// /// 发送数据前的事件 /// public event EventHandler PrepareSend; /// /// 触发发送数据前的事件 /// /// private void RaisePrepareSend(AsyncSocketUDPState state) { if (PrepareSend != null) { PrepareSend(this, new AsyncSocketUDPEventArgs(state)); } } /// /// 数据发送完毕事件 /// public event EventHandler CompletedSend; /// /// 触发数据发送完毕的事件 /// /// private void RaiseCompletedSend(AsyncSocketUDPState state) { if (CompletedSend != null) { CompletedSend(this, new AsyncSocketUDPEventArgs(state)); } } /// /// 网络错误事件 /// public event EventHandler NetError; /// /// 触发网络错误事件 /// /// private void RaiseNetError(AsyncSocketUDPState state) { if (NetError != null) { NetError(this, new AsyncSocketUDPEventArgs(state)); } } /// /// 异常事件 /// public event EventHandler OtherException; /// /// 触发异常事件 /// /// private void RaiseOtherException(AsyncSocketUDPState state, string descrip) { if (OtherException != null) { OtherException(this, new AsyncSocketUDPEventArgs(descrip, state)); } } private void RaiseOtherException(AsyncSocketUDPState state) { RaiseOtherException(state, ""); } #endregion #region Close /// /// 关闭一个与客户端之间的会话 /// /// 需要关闭的客户端会话对象 public void Close(AsyncSocketUDPState state) { if (state != null) { //_clients.Remove(state); //_clientCount--; //TODO 触发关闭事件 } } /// /// 关闭所有的客户端会话,与所有的客户端连接会断开 /// public void CloseAllClient() { //foreach (AsyncUDPSocketState client in _clients) //{ // Close(client); //} //_clientCount = 0; //_clients.Clear(); } #endregion #region 释放 /// /// Performs application-defined tasks associated with freeing, /// releasing, or resetting unmanaged resources. /// public void Dispose() { Dispose(true); GC.SuppressFinalize(this); } /// /// Releases unmanaged and - optionally - managed resources /// /// true to release /// both managed and unmanaged resources; false /// to release only unmanaged resources. 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 }}
会话封装类
using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Net;using System.Net.Sockets;namespace NetFrame.Net.UDP.Sock.Asynchronous{ public class AsyncSocketUDPState { // 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 EndPoint remote = new IPEndPoint(IPAddress.Any, 0); }}
Socket异步UDP服务器事件参数类
using System;using System.Collections.Generic;using System.Linq;using System.Text;namespace NetFrame.Net.UDP.Sock.Asynchronous{ /// /// SOCKET 异步UDP 事件类 /// public class AsyncSocketUDPEventArgs : EventArgs { /// /// 提示信息 /// public string _msg; /// /// 客户端状态封装类 /// public AsyncSocketUDPState _state; /// /// 是否已经处理过了 /// public bool IsHandled { get; set; } public AsyncSocketUDPEventArgs(string msg) { this._msg = msg; IsHandled = false; } public AsyncSocketUDPEventArgs(AsyncSocketUDPState state) { this._state = state; IsHandled = false; } public AsyncSocketUDPEventArgs(string msg, AsyncSocketUDPState state) { this._msg = msg; this._state = state; IsHandled = false; } }}
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