连接丢失后网络流不再有效

Question

我正在 xamarin 中开发一个连接到服务器的 android 应用程序。服务器应用程序根据客户端连接遵循流程等。但是，如果我说将设备转为飞行模式，然后关闭飞行模式，连接将不再有效。基本上在现实世界中，问题是用户将使用 android 设备，该设备可能会因 wifi 干扰等而导致短暂的连接丢失。我尝试了 "reconnect" 技术（正如我注意到 Tcp.Connected value was still true) 通过简单地尝试 reaqcuire NetworkStream 但是它没有工作。下面是代码：

    public NetworkStream NetworkStream;
    public TcpClient TcpClient;
    public string LastGetData = null;
    public string LastPostData = null;
    public bool Disconnected = true;

    public Stream InitializeStream(IPAddressAndPort ipObject)
    {
        NetworkStream clientStream = null;

        try
        {
            IPAddress address = IPAddress.Parse(ipObject.Address);

            TcpClient client = new TcpClient();

            client.SendTimeout = 3000;

            IPEndPoint serverEndPoint = new IPEndPoint(address, ipObject.Port);

            client.ConnectAsync(serverEndPoint.Address, serverEndPoint.Port).Wait(5000);

            if (client.Connected)
            {
                clientStream = client.GetStream();

                TcpClient = client;
                NetworkStream = clientStream;
                Disconnected = false;

                SendData("CLIENTSOFTWARENAME");
                string initReturnValue = ReadData();

                LastGetData = initReturnValue;
            }
        }
        catch (Exception ex)
        {
            LastGetData = ex.Message;
        }

        return clientStream;
    }

    public void AttemptReconnect()
    {
        if (TcpClient != null)
        {
            try
            {
                if (TcpClient.Connected)
                {
                    NetworkStream clientStream = TcpClient.GetStream();

                    NetworkStream = clientStream;
                    Disconnected = false;
                }
            }
            catch (Exception ex)
            {
                LastGetData = ex.Message;
            }
        }
    }

    public string RunCommand(string dataToSend)
    {
        string returnValue = string.Empty;
        try
        {
            if (Disconnected) AttemptReconnect();

            SendData(dataToSend);
            returnValue = ReadData();

            if (returnValue == string.Empty)
                Disconnected = true;
        }
        catch
        {
            returnValue = "An error occured during the action!  Please logout and try again.";
        }
        return returnValue;
    }

    public void SendData(string dataToSend)
    {
        if (NetworkStream != null)
        {
            var serverStream = NetworkStream;

            byte[] outStream = System.Text.Encoding.UTF8.GetBytes(dataToSend);
            serverStream.Write(outStream, 0, outStream.Length);
            serverStream.Flush();

            LastPostData = dataToSend;
        }
    }

    public string ReadData()
    {
        if (NetworkStream != null)
        {
            string returnValue = string.Empty;
            byte[] bReads = new byte[1024];
            int readAmount = 0;
            DateTime endProcess = DateTime.Now.AddSeconds(20);

            while (returnValue == string.Empty && endProcess > DateTime.Now)
            {
                while (NetworkStream.DataAvailable)
                {
                    readAmount = NetworkStream.Read(bReads, 0, bReads.Length);
                    returnValue += string.Format("{0}", Encoding.UTF8.GetString(bReads, 0, readAmount));
                }
            }

            LastGetData = returnValue;

            return returnValue;
        }

        return null;
    }

Answer 1

已解决：NetworkStream 或 TCPClient 一旦报错就没用了。我们决定存储有关设备的信息，以便重新连接到现有进程并创建新的 TCPClient 和 NetworkStream

连接丢失后网络流不再有效

Network stream no longer works after connection loss

c#

xamarin.android

tcpclient

networkstream

disconnection