异步C#服务器连续从多个套接字读取数据

3

我正在使用在这里找到的MSDN服务器示例

http://msdn.microsoft.com/en-us/library/fx6588te(v=vs.110).aspx?cs-save-lang=1&cs-lang=csharp#code-snippet-1

我的问题是这段代码只能持续接受新客户端,我希望它能够持续从所有接受的客户端接收数据。这段代码接受一个客户端,然后接收一条消息并发送一条消息,就这样。我唯一想到的方法是将异步接收方法放在while(true)循环中,但这听起来不对。我稍微改了一下示例,但基本功能仍然相同。
public class AServer
{
    // Thread signal.
    public static ManualResetEvent allDone = new ManualResetEvent(false); 
    Socket listener;
    ArrayList clients;

    public AServer(int port)
    {
        // Establish the local endpoint for the socket.
        // The DNS name of the computer
        // running the listener is "host.contoso.com".
        IPHostEntry ipHostInfo = Dns.GetHostEntry(Dns.GetHostName());
        IPAddress ipAddress = ipHostInfo.AddressList[0];
        IPEndPoint localEndPoint = new IPEndPoint(IPAddress.IPv6Any, port);

        clients = new ArrayList();

        // Create a TCP/IP socket.
        listener = new Socket(AddressFamily.InterNetworkV6, SocketType.Stream, ProtocolType.Tcp);
        listener.SetSocketOption(SocketOptionLevel.IPv6, (SocketOptionName)27, 0);
        listener.Bind(localEndPoint);
        listener.Listen(100);
    }

    public void ServerLoop(){
        while (true)
        {
            // Set the event to nonsignaled state.
            allDone.Reset();

            // Start an asynchronous socket to listen for connections.
            Console.WriteLine("Waiting for a connection...");
            listener.BeginAccept(new AsyncCallback(AcceptCallback),listener);

            // Wait until a connection is made before continuing.
            allDone.WaitOne();
        }

    }

    public void AcceptCallback(IAsyncResult ar)
    {
        // Signal the main thread to continue.
        allDone.Set();

        // Get the socket that handles the client request.
        Socket listener = (Socket)ar.AsyncState;
        Socket handler = listener.EndAccept(ar);

        // Create the state object.
        ClientData state = new ClientData();
        state.workSocket = handler;
        clients.Add(state);

        handler.BeginReceive(state.buffer, 0, ClientData.BufferSize, 0,new AsyncCallback(ReadCallback), state);
        Console.WriteLine("we passed handler.BeginReceive");
    }

    public void ReadCallback(IAsyncResult ar)
    {
        // Retrieve the state object and the handler socket
        // from the asynchronous state object.
        ClientData data = (ClientData)ar.AsyncState;
        String buff = String.Empty;
        Socket handler = data.workSocket;

        // Read data from the client socket. 
        int bytesRead = handler.EndReceive(ar);

        if (bytesRead > 0)
        {
            // There  might be more data, so store the data received so far.
            buff = Encoding.ASCII.GetString(data.buffer, 0, bytesRead);
            ParseBuffer(buff);
            Send(handler, "1");
        }
        if (bytesRead == 0) {
            CloseConnection(handler);
        }
    }

    private bool ParseBuffer(String buff) {
        Console.WriteLine(buff);
        switch (buff[0]) { 
            case '0':

                break;
            case '1':
                break;
        }

        return true;
    }

    private static void Send(Socket handler, String data)
    {
        // Convert the string data to byte data using ASCII encoding.
        byte[] byteData = Encoding.ASCII.GetBytes(data);

        // Begin sending the data to the remote device.
        handler.BeginSend(byteData, 0, byteData.Length, 0, new AsyncCallback(SendCallback), handler);
    }

    private static void SendCallback(IAsyncResult ar)
    {
        // Retrieve the socket from the state object.
        Socket handler = (Socket)ar.AsyncState;

        // Complete sending the data to the remote device.
        int bytesSent = handler.EndSend(ar);
    }

    private static void CloseConnection(Socket handler)
    {
        handler.Shutdown(SocketShutdown.Both);
        handler.Close();
    }
}

当然,我的主要方法只是按顺序调用构造函数和循环。ArrayList是我尝试解决这个问题时的遗物。
编辑
我在寻找与C中Select提供给我的相同类型的功能,但显然C#可以通过事件做到同样的事情。
1个回答

2
在您的ReadCallback中,您需要再次发布异步的Receive:
public void ReadCallback(IAsyncResult ar)
{
    // Retrieve the state object and the handler socket
    // from the asynchronous state object.
    ClientData data = (ClientData)ar.AsyncState;
    String buff = String.Empty;
    Socket handler = data.workSocket;

    // Read data from the client socket. 
    int bytesRead = handler.EndReceive(ar);

    if (bytesRead > 0)
    {
        // There  might be more data, so store the data received so far.
        buff = Encoding.ASCII.GetString(data.buffer, 0, bytesRead);
        ParseBuffer(buff);
        Send(handler, "1");

        // Here, you need to Receive again
        handler.BeginReceive(state.buffer, 0, ClientData.BufferSize, 0,new AsyncCallback(ReadCallback), state);
    }
    if (bytesRead == 0) {
        CloseConnection(handler);
    }
}   

这样,您将在每个套接字上接收、发送、接收、发送、接收、发送等。您需要进行错误处理,一个合适的服务器需要处理不完整的消息,但这是一般的想法。

顺便说一句,在您的接受回调中,类似地,您必须发布另一个异步接受:

public void AcceptCallback(IAsyncResult ar)
{
    // Signal the main thread to continue.
    allDone.Set();

    // Get the socket that handles the client request.
    Socket listener = (Socket)ar.AsyncState;
    Socket handler = listener.EndAccept(ar);

    // Create the state object.
    ClientData state = new ClientData();
    state.workSocket = handler;
    clients.Add(state);

    handler.BeginReceive(state.buffer, 0, ClientData.BufferSize, 0,new AsyncCallback(ReadCallback), state);
    Console.WriteLine("we passed handler.BeginReceive");

    // Here, you must start a new accept:
    listener.BeginAccept(new AsyncCallback(AcceptCallback),listener);
}

那听起来不错。我现在在家,没有代码,但我觉得你懂了。 - user3796261

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