網上模板：

    public class Socket_wrapper
    {
        public static Socket theSocket = null;
        private static string remoteHost = "192.168.1.14";
        private static int remotePort = 6666;

        private static String SockErrorStr = null;
        private static ManualResetEvent TimeoutObject = new
 
 ManualResetEvent(false);
        private static Boolean IsconnectSuccess = false; //異步連接情況，由異步連接回調函數置位  
        private static object lockObj_IsConnectSuccess = new object();

        /// 設置心跳  
        ///   
        private static void SetXinTiao()
        {
            //byte[] inValue = new byte[] { 1, 0, 0, 0, 0x20, 0x4e, 0, 0, 0xd0, 0x07, 0, 0 };
 
// 首次探測時間20 秒, 間隔偵測時間2 秒  
            byte[] inValue = new byte[] { 1, 0, 0, 0, 0x88, 0x13, 0, 0, 0xd0, 0x07, 0, 0 };// 首次探測時間5 秒, 間隔偵測時間2 秒  
            theSocket.IOControl(IOControlCode.KeepAliveValues, inValue, null);
        }

        /// 創建套接字+異步連接函數  
        ///   
        ///   
        private static bool socket_create_connect()
        {
            IPAddress ipAddress 
 
= IPAddress.Parse(remoteHost);
            IPEndPoint remoteEP = new IPEndPoint(ipAddress, remotePort);
            theSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
            theSocket.SendTimeout = 1000;

            SetXinTiao();//設置心跳參數  

            #region 異步連接代碼

            TimeoutObject.Reset(); //復位timeout事件  
            try
            {
                theSocket.BeginConnect(remoteEP, connectedCallback, theSocket);
            }
            catch (Exception err)
            {
                SockErrorStr = err.ToString();
                return false;
            }
            if (TimeoutObject.WaitOne(10000, false))//直到timeout，或者TimeoutObject.set()  
            {
                if (IsconnectSuccess)
                {
                    return true;
                }
                else
                {
                    return false;
                }
            }
            else
            {
                SockErrorStr = "Time Out";
                return false;
            }
            #endregion
        }

        /// 異步連接回調函數  
        ///   
        ///   
        static void connectedCallback(IAsyncResult iar)
        {
            #region <remarks>
            /// 1、置位IsconnectSuccess  
            #endregion </remarks>

            lock (lockObj_IsConnectSuccess)
            {
                Socket client = (Socket)iar.AsyncState;
                try
                {
                    client.EndConnect(iar);
                    IsconnectSuccess = true;
                    //StartKeepAlive(); //開始KeppAlive檢測  
                }
                catch (Exception e)
                {
                    //Console.WriteLine(e.ToString());  
                    SockErrorStr = e.ToString();
                    IsconnectSuccess = false;
                }
                finally
                {
                    TimeoutObject.Set();
                }
            }
        } 

        /// 同步receive函數  
        ///   
        ///   
        ///   
        public string socket_receive(byte[] readBuffer)
        {
            while (true)
            {
                try
                {
                    if (theSocket == null)
                    {
                        if (!socket_create_connect())
                        {
                            Thread.Sleep(1000);
                            continue;
                        }
                    }
                    else if (!theSocket.Connected)
                    {
                        if (!IsSocketConnected())
                            if (!Reconnect())
                            {
                                Thread.Sleep(1000);
                                continue;
                            }
                    }

                    int bytesRec = theSocket.Receive(readBuffer);

                    if (bytesRec == 0)
                    {
                        //warning 0 bytes received
                        if (!Reconnect())
                        {
                            Thread.Sleep(1000);
                            continue;
                        }
                    }
                    return Encoding.ASCII.GetString(readBuffer, 0, bytesRec);
                }
                catch (SocketException se)
                {
                    //print se.ErrorCode  
                    throw;
                }
            }
        }

        /// 同步send函數  
        ///   
        ///   
        ///   
        public bool socket_send(string sendMessage)
        {
            if (checkSocketState())
            {
                return SendData(sendMessage);
            }
            return false;
        }

        /// 同步發送  
        ///   
        ///   
        ///   
        public static bool SendData(string dataStr)
        {
            bool result = false;
            if (dataStr == null || dataStr.Length < 0)
                return result;
            try
            {
                byte[] cmd = Encoding.Default.GetBytes(dataStr);
                int n = theSocket.Send(cmd);
                if (n < 1)
                    result = false;
            }
            catch (Exception ee)
            {
                SockErrorStr = ee.ToString();
                result = false;
            }
            return result;
        }

        /// 當socket.connected為false時，進一步確定下當前連接狀態  
        ///   
        ///   
        private bool IsSocketConnected()
        {
            #region remarks
            /******************************************************************************************** 
             * 當Socket.Conneted為false時， 如果您需要確定連接的當前狀態，請進行非阻塞、零字節的 Send 調用。 
             * 如果該調用成功返回或引發 WAEWOULDBLOCK 錯誤代碼 (10035)，則該套接字仍然處於連接狀態；  
             * 否則，該套接字不再處於連接狀態。 
             * Depending on http://msdn.microsoft.com/zh-cn/library/system.net.sockets.socket.connected.aspx?cs-save-lang=1&cs-lang=csharp#code-snippet-2 
            ********************************************************************************************/
            #endregion

            #region 過程
            // This is how you can determine whether a socket is still connected.  
            bool connectState = true;
            bool blockingState = theSocket.Blocking;
            try
            {
                byte[] tmp = new byte[1];

                theSocket.Blocking = false;
                theSocket.Send(tmp, 0, 0);
                //Console.WriteLine("Connected!");  
                connectState = true; //若Send錯誤會跳去執行catch體，而不會執行其try體裏其之後的代碼  
            }
            catch (SocketException e)
            {
                // 10035 == WSAEWOULDBLOCK  
                if (e.NativeErrorCode.Equals(10035))
                {
                    //Console.WriteLine("Still Connected, but the Send would block");  
                    connectState = true;
                }

                else
                {
                    //Console.WriteLine("Disconnected: error code {0}!", e.NativeErrorCode);  
                    connectState = false;
                }
            }
            finally
            {
                theSocket.Blocking = blockingState;
            }

            //Console.WriteLine("Connected: {0}", client.Connected);  
            return connectState;
            #endregion
        }

        /// 斷線重連函數  
        ///   
        ///   
        private static bool Reconnect()
        {
            //關閉socket  
            theSocket.Shutdown(SocketShutdown.Both);

            theSocket.Disconnect(true);
            IsconnectSuccess = false;

            theSocket.Close();

            //創建socket  
            return socket_create_connect();
        }

        /// 檢測socket的狀態  
        ///   
        ///   
        public static bool checkSocketState()
        {
            try
            {
                if (theSocket == null)
                {
                    return socket_create_connect();
                }
                else if (IsconnectSuccess)
                {
                    return true;
                }
                else//已創建套接字，但未connected  
                {
                    #region 異步連接代碼

                    TimeoutObject.Reset(); //復位timeout事件  
                    try
                    {
                        IPAddress ipAddress = IPAddress.Parse(remoteHost);
                        IPEndPoint remoteEP = new IPEndPoint(ipAddress, remotePort);
                        theSocket.BeginConnect(remoteEP, connectedCallback, theSocket);

                        SetXinTiao();//設置心跳參數  
                    }
                    catch (Exception err)
                    {
                        SockErrorStr = err.ToString();
                        return false;
                    }
                    if (TimeoutObject.WaitOne(2000, false))//直到timeout，或者TimeoutObject.set()  
                    {
                        if (IsconnectSuccess)
                        {
                            return true;
                        }
                        else
                        {
                            return false;
                        }
                    }
                    else
                    {
                        SockErrorStr = "Time Out";
                        return false;
                    }

                    #endregion
                }

            }
            catch (SocketException se)
            {
                SockErrorStr = se.ToString();
                return false;
            }
        } 
    }

個人簡化改進：

 public void SocketCreateConnect()
        {
            try
            {
                tcpClient = new TcpClient(localEP);
                tcpClient.BeginConnect(remoteEP.Address, remoteEP.Port, ConnectedCallback, tcpClient);
            }
            catch
            { }

        }

        /// 異步連接回調函數  
        ///   
        /// 
        private void ConnectedCallback(IAsyncResult iar)
        {
            #region <remarks>
            /// 1、置位IsconnectSuccess  
            #endregion </remarks>

            lock (lockObj_IsConnectSuccess)
            {
                TcpClient tcpClient = (TcpClient)iar.AsyncState;
                try
                {
                    tcpClient.EndConnect(iar);
                    //IsconnectSuccess = true;
                    Receive_Radar29();
                }
                catch (Exception e)
                {
                    //IsconnectSuccess = false;
                    Thread.Sleep(10000);
                    tcpClient.BeginConnect(remoteEP.Address, remoteEP.Port, ConnectedCallback, tcpClient);
                }
            }
        }

        /// 當socket.connected為false時，進一步確定下當前連接狀態  
        ///   
        ///   
        private bool IsSocketConnected()
        {
            #region remarks
            /******************************************************************************************** 
             * 當Socket.Conneted為false時， 如果您需要確定連接的當前狀態，請進行非阻塞、零字節的 Send 調用。 
             * 如果該調用成功返回或引發 WAEWOULDBLOCK 錯誤代碼 (10035)，則該套接字仍然處於連接狀態；  
             * 否則，該套接字不再處於連接狀態。 
             * Depending on http://msdn.microsoft.com/zh-cn/library/system.net.sockets.socket.connected.aspx?cs-save-lang=1&cs-lang=csharp#code-snippet-2 
            ********************************************************************************************/
            #endregion

            #region 過程
            // This is how you can determine whether a socket is still connected.  
            bool connectState = true;
            bool blockingState = tcpClient.Client.Blocking;
            try
            {
                byte[] tmp = new byte[1];

                tcpClient.Client.Blocking = false;
                tcpClient.Client.Send(tmp, 0, 0);
                //Console.WriteLine("Connected!");  
                connectState = true; //若Send錯誤會跳去執行catch體，而不會執行其try體裏其之後的代碼  
            }
            catch (SocketException e)
            {
                // 10035 == WSAEWOULDBLOCK  
                if (e.NativeErrorCode.Equals(10035))
                {
                    //Console.WriteLine("Still Connected, but the Send would block");  
                    connectState = true;
                }

                else
                {
                    //Console.WriteLine("Disconnected: error code {0}!", e.NativeErrorCode);  
                    connectState = false;
                }
            }
            finally
            {
                tcpClient.Client.Blocking = blockingState;
            }

            //Console.WriteLine("Connected: {0}", client.Connected);  
            return connectState;
            #endregion
        }

        /// 斷線重連函數  
        ///   
        ///   
        private void Reconnect()
        {
            //IsconnectSuccess = false;

            tcpClient.Close();
            streamToServer.Close();

            //創建socket  
            SocketCreateConnect();
        }

        private void Receive_Radar29()
        {
            buffer = new byte[BufferSize];
            while (true)
            {
                try
                {
                    if (!tcpClient.Client.Connected)
                    {
                        if (!IsSocketConnected())
                        {
                            Reconnect();
                            return;
                        }
                    }

                    streamToServer = tcpClient.GetStream();
                    int count = streamToServer.Read(buffer, 0, BufferSize);
                    if (count == 0)
                    {
                        Reconnect();
                        return;
                    }
                    temp_buffer = new byte[count];
                    Array.Copy(buffer, 0, temp_buffer, 0, temp_buffer.Length);
                    Array.Clear(buffer, 0, buffer.Length);
                    List<byte[]> protocolList = requestHandler.GetActualProtocolByte(temp_buffer.ToList());
                    foreach (var item in protocolList)
                    {
                        Task.Factory.StartNew(ProcessProtocol, item);
                        //ProcessProtocol(item);
                    }
                }
                catch
                {
                    //if (streamToServer != null)
                    //{
                    //    streamToServer.Close();
                    //}
                    //tcpClient.Close();
                    //break;
                    continue;
                }
            }
        }

TCP自動重連