在C＃中接收和發送數據

Question

我還在努力提高我之前寫的一點點。 現在我遇到了接收數據的問題。 我有一個程序，我用它來發送字符串使用tcpClient到一個程序，我在其中偵聽指定的端口。 它工作正常，所以我決定再次向前發送數據

public static void receiveThread()
{
    while (true)
    {
        TcpListener tcpListener = new TcpListener(IPAddress.Any, port);
        tcpListener.Start();

        Console.WriteLine("Waiting for connection...");

        TcpClient tcpClient = tcpListener.AcceptTcpClient();

        Console.WriteLine("Connected with {0}", tcpClient.Client.RemoteEndPoint);

        while (!(tcpClient.Client.Poll(20, SelectMode.SelectRead)))
        {
            NetworkStream networkStream = tcpClient.GetStream();
            StreamReader streamReader = new StreamReader(networkStream);

            data = streamReader.ReadLine();

            if (data != null)
            {
                Console.WriteLine("Received data: {0}", data);
                send(data); // Here Im using send Method
            }
        }
        Console.WriteLine("Dissconnected...\n");
        tcpListener.Stop();
    }
}

/// <summary>
/// Sending data
/// </summary>
/// <param name="data">Data to send</param>
public static void send(string data)
{
    TcpClient tcpClient = new TcpClient();
    try
    {
        tcpClient.Connect(ipAddress, sendPort);
        Console.WriteLine("Connected with {0}", tcpClient.Client.RemoteEndPoint);
    }
    catch (Exception e)
    {
        Console.WriteLine(e);
    }
    if (tcpClient.Connected)
    {
        NetworkStream networkStream = tcpClient.GetStream();
        StreamWriter streamWriter = new StreamWriter(networkStream);
        Console.WriteLine("Messege {0} to {1}", data, tcpClient.Client.RemoteEndPoint);
        streamWriter.WriteLine(data);
        streamWriter.Flush();
        tcpClient.Close();
    }
}

有時它工作正常，但更常見的是，我們稱之為接收器，無法得到我想發送的東西。 我真的不知道它有什么問題。 看起來send方法可能有問題。 這是接收器輸出的示例

Waiting for connection...
Connected with 127.0.0.1:52449
Dissconnected...

Waiting for connection...
Connected with 127.0.0.1:52450
Received data: qweqwe
Dissconnected...

Waiting for connection...
Connected with 127.0.0.1:52451
Dissconnected...

Waiting for connection...
Connected with 127.0.0.1:52452
Dissconnected...

Waiting for connection...
Connected with 127.0.0.1:52453
Received data: zxczx
Dissconnected...

Waiting for connection...
Connected with 127.0.0.1:52454
Dissconnected...

Waiting for connection...
Connected with 127.0.0.1:52455
Received data: aasd
Dissconnected...

Waiting for connection...
Connected with 127.0.0.1:52457
Received data: www
Dissconnected...

Answer 1

這里有幾個問題：

1. StreamReader有一個4kB的緩沖區，在第一次調用ReadLine()會嘗試盡可能多地讀取。 結果是您可能在StreamReader中有數據，並且當沒有更多可用數據時進入Poll（），因為它已被讀取。
2. Poll()需要幾微秒。 等待0.02ms的傳入數據很可能會返回false，除非在調用Poll()之前存在數據。
3. 您可以在每次迭代時創建一個新的StreamReader，這可能會丟棄先前已讀取的數據。

如果您只是想讀取行並想要超時和StreamReader ，我會做類似的事情：

delegate string ReadLineDelegate ();
...
using (NetworkStream networkStream = tcpClient.GetStream()) {
    StreamReader reader = new StreamReader(networkStream);
    ReadLineDelegate rl = new ReadLineDelegate (reader.ReadLine);
    while (true) {
        IAsyncResult ares = rl.BeginInvoke (null, null);
        if (ares.AsyncWaitHandle.WaitOne (100) == false)
            break; // stop after waiting 100ms
        string str = rl.EndInvoke (ares);
        if (str != null) {
            Console.WriteLine ("Received: {0}", str);
            send (str);
        } 
    }
}

Answer 2

在追逐鬼魂之前，確保數據實際存在於流上。 如果有ALWAYS數據我們可以解決問題，但是從邏輯上看它看起來好像流被淘汰或者它上面沒有數據。