Question

当尝试通过TCP接收字符串或文件内容（作为字符串）时，我遇到了一个问题，尽管通常接收工作正常，但是该行

print("TCP -> Data received:\n" + file + "\n\n" + totalrecbytes + " Bytes");

有点停滞不前，直到我主动断开与服务器端的连接。比预期的要好。

我调试并接收了内部数据

while ((recBytes = netstream.Read(bytes, 0, bytes.Length)) > 0)

循环工作正常。它还会在正确的时刻结束循环。但是之后，什么也没发生。我没有收到错误，没有在任何循环中被“困住”，但是也没有得到预期的输出

print("TCP -> Data received:\n" + file + "\n\n" + totalrecbytes + " Bytes");

直到我与服务器端断开连接。我看不到预期的输出，并且客户端断开了连接。

这里是实现（原始source）

private Thread _tcpThread;
private TcpClient _socketConnection;

public void Connect()
{
    try
    {
        _tcpThread = new Thread(ReciveDataClient);
        _tcpThread.IsBackground = true;
        _tcpThread.Start();
    }
    catch (Exception e)
    {
        print(e.Message);
    }
}

private void ReciveDataClient()
{
    try
    {
        _socketConnection = new TcpClient("xxx.xxx.xxx.xxx", 54321);
        print(this, "TCP -> Connection Success!");
    }
    catch (Exception e)
    {
        print("connection error: " + e.Message)
        return;
    }

    try
    {
        var bytes = new byte[BUFFER_SIZE];

        while (_socketConnection.Connected)
        {
            if (_socketConnection.Available <= 0) continue;

            // Get a stream object for reading              
            var netstream = _socketConnection.GetStream();

            int totalrecbytes = 0;

            int recBytes;
            string file = "";

            // Read incomming stream into byte arrary.                  
            while ((recBytes = netstream.Read(bytes, 0, bytes.Length)) > 0)
            {
                var incommingData = new byte[recBytes];
                Array.Copy(bytes, 0, incommingData, 0, recBytes);
                // Convert byte array to string message.                        
                var serverMessage = Encoding.ASCII.GetString(incommingData);
                file += serverMessage;
                totalrecbytes += recBytes;
            }

            print("TCP -> Data received:\n" + file + "\n\n" + totalrecbytes + " Bytes");

            netstream.Close();
        }

        print("TCP -> connection was terminated by the server");
    }
    catch (Exception e)
    {
        print(e.Message)
        return;
    }
}

我希望我可以保持连接活跃，但仍可以正确接收数据并通过持久的TCP连接与服务器通信。

我在这里想念什么或做错什么了？

到目前为止，我唯一能找到的解决方法是在发送数据后始终与服务器端断开连接，并在我的代码中将整个ReceiveDataClient包裹在while循环中，如

private void ReciveDataClient()
{
    while (true)
    {
        try
        {
            _socketConnection = new TcpClient(_server.ToString(), _server.Port);

            //...

为了在服务器发送一些数据并断开客户端连接后立即开始新的连接。

Answer 1

借助Damien_The_Unbeliever和Immersive的帮助，我可以弄清楚。确实可以不时阅读文档，特别是在您第一次使用^^

时

NetworkStream.Read是阻止的调用，且文档规定为

返回：从NetworkStream读取的字节数，如果套接字已关闭，则为0。

当然，while循环实际上从未终止。

因此，采用那里提供的示例对我有用，除了如果服务器终止连接时，我遇到了另一个问题，因此我没有检查_socketConnection.IsConnected，而是使用了this post的标记答案，因此所有这些工作正常现在对我来说

private Thread _tcpThread;
private TcpClient _socketConnection;

public void Connect()
{
    if(_socketConnection != null) return;

    try
    {
        _tcpThread = new Thread(ReciveDataClient);
        _tcpThread.IsBackground = true;
        _tcpThread.Start();
    }
    catch (Exception e)
    {
        print("TCP -> Thread error: " + e.Message);
    }
}

public void Disconnect()
{
    if(_socketConnection = null) return;

    _tcpThread.Abort();
}

private void ReciveDataClient()
{
    try
    {
        _socketConnection = new TcpClient("xxx.xxx.xxx.xxx", 54321);
        print(this, "TCP -> Connection Success!");
    }
    catch (Exception e)
    {
        print("TCP -> connection error: " + e.Message)
        return;
    }

    try
    {
        while(true)
        {
            // Get a stream object for reading              
            var netstream = _socketConnection.GetStream();

            //Check if still connected                
            if(_socketConnection.Client.Poll(0, SelectMode.SelectRead))
            {
                byte[] buff = new byte[1];
                if( _socketConnection.Client.Receive( buff, SocketFlags.Peek ) == 0 )
                {
                    // Server disconnected or connection lost
                    break;
                }
            }

            // Check to see if this NetworkStream is readable.
            if(myNetworkStream.CanRead)
            {
                byte[] myReadBuffer = new byte[BUFFER_SIZE];
                StringBuilder myCompleteMessage = new StringBuilder();
                int numberOfBytesRead = 0;
                int totalBytesReceived = 0;

                // Incoming message may be larger than the buffer size.
                do
                {
                    numberOfBytesRead = myNetworkStream.Read(myReadBuffer, 0, myReadBuffer.Length);
                    myCompleteMessage.AppendFormat("{0}", Encoding.ASCII.GetString(myReadBuffer, 0, numberOfBytesRead));    
                    totalBytesReceived += numberOfBytesRead;        
                }
                while(myNetworkStream.DataAvailable);

                // Print out the received message to the console.
                print("TCP -> Data received:\n" + myCompleteMessage.ToString() + "\n\n" + totalrecbytes + " Bytes");
            }
            else
            {
                //Prevent a direct loop
                Thread.Sleep(100);
            }          
        }

        print("TCP -> connection was terminated by the server");
    }
    catch(ThreadAbortException)
    {
        print("TCP -> Disconnected");
    }
    catch(Exception e)
    {
        print(e.Message)
    }

    // Clean up
    _socketConnection?.Close();
    _socketConnection?.Dispose();
    _socketConnection = null;
}

TCP客户端停止直到被服务器断开连接

1 个答案: