Question

我没有很好地教网络。我知道TCP / IP的基础知识，但我面临着一项任务，我必须为多个项目管理多个线程，这些项目在同一个解决方案中相互通信。我正在使用Window的Forms，C＃，为了简单起见，我只会写下需要编写的内容。

这是我的Client类，它连接到服务器，处理来往服务器的消息，并从服务器注销。

private TcpClient ClientConnection = null;
private NetworkStream CommandStream = null;

private Thread ClientThread = null;
bool isRunning = false;

public Client()
{
    InitializeComponent();
    try
    {
        //open the connection to the command port
        ClientConnection = new TcpClient(address, Convert.ToInt32(port));

        //Get the command stream
        CommandStream = ClientConnection.GetStream();
        if (CommandStream != null)
        {
            isConnected = true;
            ClientThread = new Thread(Receive);
            isRunning = true;
            ClientThread.Start();
        }
        errorLabel.Visible = false;
    }
    catch (Exception ex)
    {
        errorLabel.Visible = true;
        errorLabel.Text = "Failed to Connect";
    }
}

private void Receive()
{
    Byte[] data = new Byte[1024];
    string message = string.Empty;
    int BytesReceived = 0;

    while (isRunning == true)
    {
        BytesReceived = CommandStream.Read(data, 0, 1024);
        message = Encoding.ASCII.GetString(data, 0, BytesReceived);

        //Do something with the message
    }
}

private void logoutButton_Click(object sender, EventArgs e)
    {
        //Do logout logic here
        errorLabel.Visible = false;

        try
        {
            if (ClientConnection != null)
            {
                Byte[] command = new Byte[1024];
                string commandStr = "SHUTDOWN";
                command = Encoding.ASCII.GetBytes(commandStr);
                CommandStream.Write(command, 0, command.GetLength(0));

                ClientConnection.Close();
                CommandStream.Close();
                isRunning = false;

                if (ClientThread.IsAlive == true)
                {
                    errorLabel.Visible = true;
                    errorLabel.Text = "Thread still alive. Failed to Disconnect";
                }
            }
        }
        catch(Exception ex)
        {
            errorLabel.Visible = true;
            errorLabel.Text = "Failed to Disconnect";
        }

    }

这是我的服务器类'Process Handler Function：

private void CommandProcessHandler(Socket client)
    {
        Byte[] data = new Byte[1024];
        NetworkStream NetStream = null;

        //Exception check
        if(client.Connected == true)
            NetStream = new NetworkStream(client);

        while(bCommandListener == true)
        {
            //Read the command from the client
            int bytes = NetStream.Read(data, 0, 1024);
            string Command = Encoding.ASCII.GetString(data, 0, bytes);

            //Do something with the command
            if (Command == "SHUTDOWN")
            {
                NetStream.Close();
                client.Close();
                bCommandListener = false;
                continue;
            }
            //Display the command in the command list box
            string buttonPressed;
            string buttonLetter;

            buttonPressed = CommandDataObject.Instance.DecodeUIDFromMessage(Command);
            buttonLetter = CommandDataObject.Instance.DecodeMessageFromUID(Command);

            Command = ((client.RemoteEndPoint) as IPEndPoint).Address.ToString() + ">>>" + Command;
            UpdateCommandsListBox(Command);
        } 
    }

我确信我的线程完全正常，但问题在于关闭它们。这是我从未正确教过的一个方面，我在学习上遇到了麻烦。按照目前的情况，我按下“注销”按钮，该按钮应该向服务器发送一条消息以关闭，以及关闭TcpClient和NetworkStream。它还设置isRunning bool，它使客户端的Receive线程保持活动状态为false。

然而，就目前而言，我在第98行（在客户端的Receive函数期间，当BytesReceived = CommandStream.Read期间）执行此操作时出现错误，如下所示：

An unhandled exception of type 'System.IO.IOException' occurred in System.dll

Additional information: Unable to read data from the transport connection: A blocking operation was interrupted by a call to WSACancelBlockingCall.

我不确定错误是指什么，但我已经坚持了一段时间，并想要修复它。有解决方案吗

Answer 1

当您使用NetworkStream时，如果在尝试阅读see MSDN documentation时底层套接字已关闭，它将抛出IOException。所以你的代码非常好。你只需要处理异常。

如果您直接读取套接字，则在套接字关闭时您将收到0。

如何关闭TCP / IP连接

1 个答案: