C#網路編程系列文章(五)之Socket實現非同步UDP伺服器

本文介紹

在.Net中，System.Net.Sockets 命名空間為需要嚴密控制網路訪問的開發人員提供了 Windows Sockets (Winsock) 介面的託管實現。System.Net 命名空間中的所有其他網路訪問類都建立在該通訊端Socket實現之上，如TCPClient、TCPListener 和 UDPClient 類封裝有關建立到 Internet 的 TCP 和 UDP 串連的詳細資料；NetworkStream類則提供用於網路訪問的基礎資料流等，常見的許多Internet服務都可以見到Socket的蹤影，如Telnet、Http、Email、Echo等，這些服務儘管通訊協議Protocol的定義不同，但是其基礎的傳輸都是採用的Socket。 其實，Socket可以象流Stream一樣被視為一個資料通道，這個通道架設在應用程式端（用戶端）和遠程伺服器端之間，而後，資料的讀取（接收）和寫入（發送）均針對這個通道來進行。
可見，在應用程式端或者伺服器端建立了Socket對象之後，就可以使用Send/SentTo方法將資料發送到串連的Socket,或者使用Receive/ReceiveFrom方法接收來自串連Socket的資料；
針對Socket編程，.NET 架構的 Socket 類是 Winsock32 API 提供的通訊端服務的Managed 程式碼版本。其中為實現網路編程提供了大量的方法，大多數情況下，Socket 類方法只是將資料封送到它們的本機 Win32 副本中並處理任何必要的安全檢查。如果你熟悉Winsock API函數，那麼用Socket類編寫網路程式會非常容易，當然，如果你不曾接觸過，也不會太困難，跟隨下面的解說，你會發覺使用Socket類開發windows 網路應用程式原來有規可尋，它們在大多數情況下遵循大致相同的步驟。

本節介紹使用Socket來實現一個高效能的非同步UDP伺服器，實際上UDP是不分客戶機和伺服器的，但是我們有的時候和伺服器通訊就是使用UDP來進行的。

Socket非同步UDP伺服器

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{    /// <summary>    /// SOCKET實現非同步UDP伺服器    /// </summary>    public class AsyncSocketUDPServer    {        #region Fields        /// <summary>        /// 伺服器程式允許的最大用戶端串連數        /// </summary>        private int _maxClient;        /// <summary>        /// 當前的串連的用戶端數        /// </summary>        //private int _clientCount;        /// <summary>        /// 伺服器使用的同步socket        /// </summary>        private Socket _serverSock;        /// <summary>        /// 用戶端工作階段列表        /// </summary>        //private List<AsyncUDPSocketState> _clients;        private bool disposed = false;        /// <summary>        /// 資料接受緩衝區        /// </summary>        private byte[] _recvBuffer;        #endregion        #region Properties        /// <summary>        /// 伺服器是否正在運行        /// </summary>        public bool IsRunning { get; private set; }        /// <summary>        /// 監聽的IP地址        /// </summary>        public IPAddress Address { get; private set; }        /// <summary>        /// 監聽的連接埠        /// </summary>        public int Port { get; private set; }        /// <summary>        /// 通訊使用的編碼        /// </summary>        public Encoding Encoding { get; set; }        #endregion        #region 建構函式        /// <summary>        /// 非同步Socket UDP伺服器        /// </summary>        /// <param name="listenPort">監聽的連接埠</param>        public AsyncSocketUDPServer(int listenPort)            : this(IPAddress.Any, listenPort,1024)        {        }        /// <summary>        /// 非同步Socket UDP伺服器        /// </summary>        /// <param name="localEP">監聽的終結點</param>        public AsyncSocketUDPServer(IPEndPoint localEP)            : this(localEP.Address, localEP.Port,1024)        {        }        /// <summary>        /// 非同步Socket UDP伺服器        /// </summary>        /// <param name="localIPAddress">監聽的IP地址</param>        /// <param name="listenPort">監聽的連接埠</param>        /// <param name="maxClient">最大用戶端數量</param>        public AsyncSocketUDPServer(IPAddress localIPAddress, int listenPort, int maxClient)        {            this.Address = localIPAddress;            this.Port = listenPort;            this.Encoding = Encoding.Default;            _maxClient = maxClient;            //_clients = new List<AsyncUDPSocketState>();            _serverSock = new Socket(localIPAddress.AddressFamily, SocketType.Dgram, ProtocolType.Udp);            _recvBuffer=new byte[_serverSock.ReceiveBufferSize];        }        #endregion        #region Method        /// <summary>        /// 啟動伺服器        /// </summary>        /// <returns>非同步TCP伺服器</returns>        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的區別是什麼                /*_serverSock.BeginReceive(_recvBuffer, 0, _recvBuffer.Length, SocketFlags.None,                    new AsyncCallback(ReceiveDataAsync), null);*/            }        }        /// <summary>        /// 停止伺服器        /// </summary>        public void Stop()        {            if (IsRunning)            {                IsRunning = false;                _serverSock.Close();                //TODO 關閉對所有用戶端的串連            }        }        /// <summary>        /// 接收資料的方法        /// </summary>        /// <param name="ar"></param>        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區別                //len = _serverSock.EndReceive(ar);                //TODO 處理資料                //觸發資料收到事件                RaiseDataReceived(so);            }            catch (Exception)            {                //TODO 處理異常                RaiseOtherException(so);            }            finally            {                if (IsRunning && _serverSock != null)                    _serverSock.BeginReceiveFrom(so.buffer, 0, so.buffer.Length, SocketFlags.None,                ref so.remote, new AsyncCallback(ReceiveDataAsync), so);            }        }        /// <summary>        /// 發送資料        /// </summary>        /// <param name="msg"></param>        /// <param name="remote"></param>        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 異常處理                RaiseOtherException(null);            }        }        private void SendDataEnd(IAsyncResult ar)        {            ((Socket)ar.AsyncState).EndSendTo(ar);            RaiseCompletedSend(null);        }        #endregion        #region 事件        /// <summary>        /// 接收到資料事件        /// </summary>        public event EventHandler<AsyncSocketUDPEventArgs> DataReceived;        private void RaiseDataReceived(AsyncSocketUDPState state)        {            if (DataReceived != null)            {                DataReceived(this, new AsyncSocketUDPEventArgs(state));            }        }        /// <summary>        /// 發送資料前的事件        /// </summary>        public event EventHandler<AsyncSocketUDPEventArgs> PrepareSend;        /// <summary>        /// 觸發發送資料前的事件        /// </summary>        /// <param name="state"></param>        private void RaisePrepareSend(AsyncSocketUDPState state)        {            if (PrepareSend != null)            {                PrepareSend(this, new AsyncSocketUDPEventArgs(state));            }        }        /// <summary>        /// 資料發送完畢事件        /// </summary>        public event EventHandler<AsyncSocketUDPEventArgs> CompletedSend;        /// <summary>        /// 觸發資料發送完畢的事件        /// </summary>        /// <param name="state"></param>        private void RaiseCompletedSend(AsyncSocketUDPState state)        {            if (CompletedSend != null)            {                CompletedSend(this, new AsyncSocketUDPEventArgs(state));            }        }        /// <summary>        /// 網路錯誤事件        /// </summary>        public event EventHandler<AsyncSocketUDPEventArgs> NetError;        /// <summary>        /// 觸發網路錯誤事件        /// </summary>        /// <param name="state"></param>        private void RaiseNetError(AsyncSocketUDPState state)        {            if (NetError != null)            {                NetError(this, new AsyncSocketUDPEventArgs(state));            }        }        /// <summary>        /// 例外狀況事件        /// </summary>        public event EventHandler<AsyncSocketUDPEventArgs> OtherException;        /// <summary>        /// 觸發例外狀況事件        /// </summary>        /// <param name="state"></param>        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        /// <summary>        /// 關閉一個與用戶端之間的會話        /// </summary>        /// <param name="state">需要關閉的用戶端工作階段對象</param>        public void Close(AsyncSocketUDPState state)        {            if (state != null)            {                //_clients.Remove(state);                //_clientCount--;                //TODO 觸發關閉事件            }        }        /// <summary>        /// 關閉所有的用戶端工作階段,與所有的用戶端串連會斷開        /// </summary>        public void CloseAllClient()        {            //foreach (AsyncUDPSocketState client in _clients)            //{            //    Close(client);            //}            //_clientCount = 0;            //_clients.Clear();        }        #endregion        #region 釋放        /// <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    }}

會話封裝類

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非同步UDP伺服器事件參數類

using System;using System.Collections.Generic;using System.Linq;using System.Text;namespace NetFrame.Net.UDP.Sock.Asynchronous{    /// <summary>    /// SOCKET 非同步UDP 事件類別    /// </summary>    public class AsyncSocketUDPEventArgs : EventArgs    {        /// <summary>        /// 提示資訊        /// </summary>        public string _msg;        /// <summary>        /// 用戶端狀態封裝類        /// </summary>        public AsyncSocketUDPState _state;        /// <summary>        /// 是否已經處理過了        /// </summary>        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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