c#Asynchronous Socket Tcp server implementation

/// <summary>  
    /// 异步SOCKET 服务器  
    /// </summary>  
    public class AsyncServer : 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<Session> _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 Ctors  
   
        /// <summary>  
        /// 异步Socket TCP服务器  
        /// </summary>  
        /// <param name="listenPort">监听的端口</param>  
        public AsyncServer(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 AsyncServer(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 AsyncServer(IPAddress localIPAddress, int listenPort,int maxClient)  
        {  
            this.Address = localIPAddress;  
            this.Port = listenPort;  
            this.Encoding = Encoding.Default;  
   
            _maxClient = maxClient;  
            _clients = new List<Session>();  
            _serverSock = new Socket(localIPAddress.AddressFamily, SocketType.Stream, ProtocolType.Tcp);  
        }  
  
        #endregion  
  
  
        #region Server  
   
        /// <summary>  
        /// 启动服务器  
        /// </summary>  
        /// <returns>异步TCP服务器</returns>  
        public AsyncServer Start()  
        {  
            if (!IsRunning)  
            {  
                IsRunning = true;  
                _serverSock.Bind(new IPEndPoint(this.Address, this.Port));  
                _serverSock.Listen(1024);  
                _serverSock.BeginAccept(new AsyncCallback(HandleAcceptConnected), _serverSock);  
            }  
            return this;  
        }  
   
        /// <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>  
        /// <returns>异步TCP服务器</returns>  
        public AsyncServer Start(int backlog)  
        {  
            if (!IsRunning)  
            {  
                IsRunning = true;  
                _serverSock.Bind(new IPEndPoint(this.Address, this.Port));  
                _serverSock.Listen(backlog);  
                _serverSock.BeginAccept(new AsyncCallback(HandleAcceptConnected), _serverSock);  
            }  
            return this;  
        }  
   
        /// <summary>  
        /// 停止服务器  
        /// </summary>  
        /// <returns>异步TCP服务器</returns>  
        public AsyncServer Stop()  
        {  
            if (IsRunning)  
            {  
                IsRunning = false;  
                _serverSock.Close();  
                //TODO 关闭对所有客户端的连接  
   
            }  
            return this;  
        }  
  
        #endregion  
  
        #region Receive  
        /// <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)  
                {  
                    //TODO 触发事件  
                    RaiseServerException(null);  
                }  
                else 
                {  
                    Session session = new Session(client);  
                    lock (_clients)  
                    {  
                        _clients.Add(session);  
                        _clientCount++;  
                        RaiseClientConnected(session); //触发客户端连接事件  
                    }  
                    session.RecvDataBuffer = new byte[client.ReceiveBufferSize];  
                    //开始接受来自该客户端的数据  
                    client.BeginReceive(session.RecvDataBuffer, 0, session.RecvDataBuffer.Length, SocketFlags.None,  
                     new AsyncCallback(HandleDataReceived), session);  
                }  
                //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)  
            {  
                Session session = (Session)ar.AsyncState;  
                Socket client = session.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)  
                    {  
                        //TODO 触发事件 (关闭客户端)  
                        CloseSession(session);  
                        RaiseNetError(session);  
                        return;  
                    }  
                    //TODO 处理已经读取的数据 ps:数据在session的RecvDataBuffer中  
                    RaiseDataReceived(session);  
                    //TODO 触发数据接收事件  
                }  
                catch (SocketException ex)  
                {  
                    //TODO 异常处理  
                    RaiseNetError(session);  
                }  
                finally 
                {  
                    //继续接收来自来客户端的数据  
                    client.BeginReceive(session.RecvDataBuffer, 0, session.RecvDataBuffer.Length, SocketFlags.None,  
                     new AsyncCallback(HandleDataReceived), session);  
                }  
            }  
        }  
        #endregion  
  
        #region Send  
        /// <summary>  
        /// 发送数据  
        /// </summary>  
        /// <param name="session">接收数据的客户端会话</param>  
        /// <param name="data">数据报文</param>  
        public void Send(Session session, byte[] data)  
        {  
            Send(session.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);  
        }  
        #endregion  
  
        #region Events  
        /// <summary>  
        /// 接收到数据事件  
        /// </summary>  
        public event EventHandler<EventArgs> DataReceived;  
   
        private void RaiseDataReceived(Session session)  
        {  
            if (DataReceived != null)  
            {  
                DataReceived(this, new AsyncEventArgs(session));  
            }  
        }  
   
        /// <summary>  
        /// 与客户端的连接已建立事件  
        /// </summary>  
        public event EventHandler<AsyncEventArgs> ClientConnected;  
        /// <summary>  
        /// 与客户端的连接已断开事件  
        /// </summary>  
        public event EventHandler<AsyncEventArgs> ClientDisconnected;  
   
        /// <summary>  
        /// 触发客户端连接事件  
        /// </summary>  
        /// <param name="session"></param>  
        private void RaiseClientConnected(Session session)  
        {  
            if (ClientConnected != null)  
            {  
                ClientConnected(this, new AsyncEventArgs(session));  
            }  
        }  
        /// <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 AsyncEventArgs("连接断开"));  
            }  
        }  
        /// <summary>  
        /// 网络错误事件  
        /// </summary>  
        public event EventHandler<AsyncEventArgs> NetError;  
        /// <summary>  
        /// 触发网络错误事件  
        /// </summary>  
        /// <param name="client"></param>  
        private void RaiseNetError(Session session)  
        {  
            if (NetError != null)  
            {  
                NetError(this, new AsyncEventArgs(session));  
            }  
        }  
   
        /// <summary>  
        /// 异常事件  
        /// </summary>  
        public event EventHandler<AsyncEventArgs> ServerException;  
        /// <summary>  
        /// 触发异常事件  
        /// </summary>  
        /// <param name="client"></param>  
        private void RaiseServerException(Session session)  
        {  
            if (ServerException != null)  
            {  
                ServerException(this, new AsyncEventArgs(session));  
            }  
        }  
        #endregion  
  
  
        #region Close  
        /// <summary>  
        /// 关闭一个与客户端之间的会话  
        /// </summary>  
        /// <param name="closeClient">需要关闭的客户端会话对象</param>  
        public void CloseSession(Session session)  
        {  
            if (session != null)  
            {  
                session.Datagram = null;  
                session.RecvDataBuffer = null;  
   
                _clients.Remove(session);  
                _clientCount--;  
                //TODO 触发关闭事件  
                session.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 (Session client in _clients)  
            {  
                CloseSession(client);  
            }  
            _clientCount = 0;  
            _clients.Clear();  
        }  
   
        /// <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 ex)  
                    {  
                        //TODO  
                        RaiseServerException(null);  
                    }  
                }  
                disposed = true;  
            }  
        }  
        #endregion  
    }

/// <summary>  
    /// 客户端与服务器之间的会话类  
    /// </summary>  
    public class Session  
    {  
        #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 Session(Socket cliSock)  
        {  
   
            _clientSock = cliSock;  
        }  
        /// <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();  
        }  
    }

class AsyncEventArgs : EventArgs  
    {  
        /// <summary>  
        /// 提示信息  
        /// </summary>  
        public string _msg;  
   
        public Session _sessions;  
   
        /// <summary>  
        /// 是否已经处理过了  
        /// </summary>  
        public bool IsHandled { get; set; }  
   
        public AsyncEventArgs(string msg)  
        {  
            this._msg = msg;  
            IsHandled = false;  
        }  
        public AsyncEventArgs(Session session)  
        {  
            this._sessions = session;  
            IsHandled = false;  
        }  
        public AsyncEventArgs(string msg, Session session)  
        {  
            this._msg = msg;  
            this._sessions = session;  
            IsHandled = false;  
        }  
    }