public class XmlSocket
    {

        //异步socket诊听
        // Incoming data from client.从客户端传来的数据
        public static string data = null;

        // Thread signal.线程 用一个指示是否将初始状态设置为终止的布尔值初始化 ManualResetEvent 类的新实例。
        public static ManualResetEvent allDone = new ManualResetEvent(false);
        //static void Main(string[] args)
        //{
        //    StartListening();
        //}

        public static void StartListening()
        {
            // Data buffer for incoming data. 传入数据缓冲
            byte[] bytes = new Byte[1024];
            // Establish the local endpoint for the socket. 建立本地端口
            // The DNS name of the computer
            // running the listener is "host.contoso.com".

            IPAddress ipAddress;
            String ipString = ConfigurationManager.AppSettings.Get("SocketIP");
            if (ipString==null || ipString ==String.Empty)
            {
                IPHostEntry ipHostInfo = Dns.GetHostEntry(Dns.GetHostName());
                ipAddress = ipHostInfo.AddressList[0];
            }
            else
            {
                ipAddress = IPAddress.Parse(ipString);
            }

            int port;
            String portString = ConfigurationManager.AppSettings.Get("SocketPort");
            if (portString==null || portString==String.Empty)
            {
                port = 11001;
            }
            else
            {
                port = int.Parse(portString);
            }
            IPEndPoint localEndPoint = new IPEndPoint(ipAddress, port);

            // 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.绑定端口和数据
            try
            {
                listener.Bind(localEndPoint);
                listener.Listen(100);

                while (true)
                {
                    // Set the event to nonsignaled state.设置无信号状态的事件
                    allDone.Reset();
                    // Start an asynchronous socket to listen for connections.重新 启动异步连接
                    listener.BeginAccept(new AsyncCallback(AcceptCallback), listener);
                    // Wait until a connection is made before continuing.等待连接创建后继续
                    allDone.WaitOne();
                }
            }
            catch (Exception e)
            {
                //
            }
        }

        public static void AcceptCallback(IAsyncResult ar)
        {
            try
            {
                // Signal the main thread to continue.接受回调方法 该方法的此节向主应用程序线程发出信号，
                //让它继续处理并建立与客户端的连接
                allDone.Set();
                // Get the socket that handles the client request.获取客户端请求句柄
                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);
            }
            catch (Exception e)
            {
                //
            }
        }

        /// <summary>
        /// 与接受回调方法一样，读取回调方法也是一个 AsyncCallback 委托。
        /// 该方法将来自客户端套接字的一个或多个字节读入数据缓冲区，然后再次调用 BeginReceive 方法，直到客户端发送的数据完成为止。
        /// 从客户端读取整个消息后，在控制台上显示字符串，并关闭处理与客户端的连接的服务器套接字。
        /// </summary>
        /// <param name="ar">IAsyncResult 委托</param>
        public static void ReadCallback(IAsyncResult ar)
        {
            try
            {
                String content = String.Empty;
                // Retrieve the state object and the handler socket创建自定义的状态对象 from the asynchronous state object.
                StateObject state = (StateObject)ar.AsyncState;
                Socket handler = state.workSocket;//处理的句柄
                // Read data from the client socket. 读出
                int bytesRead = handler.EndReceive(ar);
                if (bytesRead > 0)
                {
                    //业务代码
                    string result = DoSomeThing(...);
                    String len = Encoding.UTF8.GetBytes(result).Length.ToString().PadLeft(8, '0');
                    log.writeLine(len);
                    Send(len + result, handler);
                }
            }
            catch (Exception e)
            {
                //
            }

        }
        private static void Send(String data, Socket handler)
        {
            try
            {
                // Convert the string data to byte data using UTF8 encoding.
                byte[] byteData = Encoding.UTF8.GetBytes(data);
                // Begin sending the data to the remote device.
                handler.BeginSend(byteData, 0, byteData.Length, 0,
                 new AsyncCallback(SendCallback), handler);
            }
            catch (Exception e)
            {
                //
            }
        }
        /// <summary>
        /// 发送
        /// </summary>
        /// <param name="ar"></param>
        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.向远端发送数据
                int bytesSent = handler.EndSend(ar);
                StateObject state = new StateObject();
                state.workSocket = handler;

                handler.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,new AsyncCallback(ReadCallback), state);
                handler.Shutdown(SocketShutdown.Both);
                handler.Close();
            }
            catch (Exception e)
            {
//
            }
        }

        public static void StopListening()
        {
            allDone.Close();
            log.close();
        }

        /// <summary>
        /// 具体处理业务的方法
        /// </summary>
        /// <returns></returns>
        private static string DoSomething(int i)
        {
            //具体业务代码,返回需要返回的字符串信息
        }
        /// <summary>
        /// 写日志方法
        /// </summary>
        /// <param name="strLog">写入内容</param>
        public static void WriteLog(string strLog)
        {
             //写入日志代码
        }
    }