连接丢失后，网络流不再工作

Question

我正在开发一个连接到服务器的 xamarin 中的 android 应用程序。 服务器应用程序根据客户端连接遵循进程等。 但是，如果我说将设备转为飞行模式，然后关闭飞行模式，则连接不再有效。 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干扰等原因而短暂失去连接。 我已经尝试了一种"重新连接"技术(因为我注意到Tcp.Connected值仍然是真的(，只需尝试重新连接NetworkStream，但它不起作用。 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：一旦NetworkStream或TCPClient出错，它就变得毫无用处。 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