有关异步套接字操作和消息框架的 .NET 问题

    private void StartRead(Socket socket)
    {
        try
        {
            StateObject state = new StateObject();
            state.AsyncSocket = socket;
            socket.BeginReceive(state.Buffer, 0, StateObject.BufferSize, 0, new AsyncCallback(ReceiveCallback), state);
        }
        catch (SocketException)
        {
            m_Socket.Shutdown(SocketShutdown.Both);
            Disconnect();
        }
    }
    private void ReceiveCallback(IAsyncResult ar)
    {
        try
        {
            StateObject state = (StateObject)ar.AsyncState;
            int bytes_read = state.AsyncSocket.EndReceive(ar);
            char[] chars = new char[bytes_read + 1];
            System.Text.Decoder decoder = System.Text.Encoding.UTF8.GetDecoder();
            int charLength = decoder.GetChars(state.Buffer, 0, bytes_read, chars, 0);
            String data = new String(chars);
            ParseMessage(data);
            StartRead(state.AsyncSocket);
        }
        catch (SocketException)
        {
            m_Socket.Shutdown(SocketShutdown.Both);
            Disconnect();
        }
    }

在

块前面加上长度比使用分隔符更好。您不必处理任何类型的转义即可以换行符发送数据。

此答案现在可能与你无关，因为它使用 AsyncCTP 中的功能，这些功能仅在下一版本的 .net 中提供。但是，它确实使事情更加简洁。本质上，您编写的代码与同步情况的代码完全相同，但在存在异步调用的地方插入"await"语句。

    public static async Task<Byte[]> ReadChunkAsync(this Stream me) {
        var size = BitConverter.ToUInt32(await me.ReadExactAsync(4), 0);
        checked {
            return await me.ReadExactAsync((int)size);
        }
    }
    public static async Task<Byte[]> ReadExactAsync(this Stream me, int count) {
        var buf = new byte[count];
        var t = 0;
        while (t < count) {
            var n = await me.ReadAsync(buf, t, count - t);
            if (n <= 0) {
                if (t > 0) throw new IOException("End of stream (fragmented)");
                throw new IOException("End of stream");
            }
            t += n;
        }
        return buf;
    }
    public static void WriteChunk(this Stream me, byte[] buffer, int offset, int count) {
        me.Write(BitConverter.GetBytes(count), 0, 4);
        me.Write(buffer, offset, count);
    }

基本上，您创建一个缓冲区，每次接收数据时，您都会将该数据添加到缓冲区中，并确定您是否已经收到一条或多条完整的消息。

在 ReceiveCallback 和 StartRead 之间，您不会收到任何异步消息（传入的数据将自动在套接字级别缓冲），因此它是检查完整消息并将其从缓冲区中删除的理想位置。

所有变体都是可能的，包括接收消息 1 的结尾、消息 2 以及消息 3 的开头，所有这些都在一个块中。

我不建议对块进行 UTF8 解码，因为一个 UTF8 字符可能包含两个字节，如果它们在块之间拆分，您的数据可能会损坏。在这种情况下，您可以保留一个字节[]缓冲区（MemoryStream？）并在0x0A字节上拆分消息。

好的，这就是我最终所做的。我创建了一个读取器线程，该线程基于网络流创建NetworkStream和StreamReader。然后我使用StreamReader.ReadLine以这种方式读取行。这是一个同步调用，但它位于自己的线程中。它似乎工作得更好。我必须实现这一点，因为这是我们的应用程序协议（换行符分隔的消息）。我知道其他人会像我一样四处寻找答案，就像我在我的客户端类中所做的那样：

public class Client
{
    Socket              m_Socket;
    EventWaitHandle     m_WaitHandle;
    readonly object     m_Locker;
    Queue<IEvent>       m_Tasks;
    Thread              m_Thread;
    Thread              m_ReadThread;
    public Client()
    {
        m_WaitHandle = new AutoResetEvent(false);
        m_Locker = new object();
        m_Tasks = new Queue<IEvent>();
        m_Thread = new Thread(Run);
        m_Thread.IsBackground = true;
        m_Thread.Start();
    }
    public void EnqueueTask(IEvent task)
    {
        lock (m_Locker)
        {
            m_Tasks.Enqueue(task);
        }
        m_WaitHandle.Set();
    }
    private void Run()
    {
        while (true)
        {
            IEvent task = null;
            lock (m_Locker)
            {
                if (m_Tasks.Count > 0)
                {
                    task = m_Tasks.Dequeue();
                    if (task == null)
                    {
                        return;
                    }
                }
            }
            if (task != null)
            {
                task.DoTask(this);
            }
            else
            {
                m_WaitHandle.WaitOne();
            }
        }
    }
    public void Connect(string hostname, int port)
    {
        try
        {
            m_Socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
            IPAddress[] IPs = Dns.GetHostAddresses(hostname);
            m_Socket.BeginConnect(IPs, port, new AsyncCallback(ConnectCallback), m_Socket);
        }
        catch (SocketException)
        {
            m_Socket.Close();
            OnConnect(false, "Unable to connect to server.");
        }
    }
    private void ConnectCallback(IAsyncResult ar)
    {
        try
        {
            Socket socket = (Socket)ar.AsyncState;
            socket.EndConnect(ar);
            OnConnect(true, "Successfully connected to server.");
            m_ReadThread = new Thread(new ThreadStart(this.ReadThread));
            m_ReadThread.Name = "Read Thread";
            m_ReadThread.IsBackground = true;
            m_ReadThread.Start();
        }
        catch (SocketException)
        {
            m_Socket.Close();
            OnConnect(false, "Unable to connect to server.");
        }
    }
    void ReadThread()
    {
        NetworkStream networkStream = new NetworkStream(m_Socket);
        StreamReader reader = new StreamReader(networkStream);
        while (true)
        {
            try
            {
                String message = reader.ReadLine();
                // To keep the code thread-safe, enqueue a task in the CLient class thread to parse the message received.
                EnqueueTask(new ServerMessageEvent(message));
            }
            catch (IOException)
            {
                // The code will reach here if the server disconnects from the client. Make sure to cleanly shutdown...
                Disconnect();
                break;
            }
        }
    }
    ... Code for sending/parsing the message in the Client class thread.
}