C# 使用异步套接字接收数据

我使用两种方式通过连接到IP地址的套接字接收数据

同步接收。 异步接收。 使用同步接收，我在不到1秒的时间内从服务器获得所有响应。但是通过使用异步接收，接收所有响应需要30秒以上

代码如下：

 class StateObject
{
    // Client socket.
    public Socket workSocket = null;
    // Size of receive buffer.
    public const int BufferSize = 256;
    // Receive buffer.
    public byte[] buffer = new byte[BufferSize];
    // Received data string.
    public StringBuilder sb = new StringBuilder();
}

    private static void Receive(Socket client)
    {
        try
        {
            // Create the state object.
            StateObject state = new StateObject();
            state.workSocket = client;

            // Begin receiving the data from the remote device.
            client.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
                new AsyncCallback(ReceiveCallback), state);
        }
        catch (Exception e)
        {
            Console.WriteLine(e.ToString());
        }
    }

    private static void ReceiveCallback(IAsyncResult ar)
    {
        try
        {
            // Retrieve the state object and the client socket 
            // from the asynchronous state object.
            StateObject state = (StateObject)ar.AsyncState;
            Socket client = state.workSocket;
            // Read data from the remote device.
            int bytesRead = client.EndReceive(ar);
            if (bytesRead > 0)
            {
                // There might be more data, so store the data received so far.
                state.sb.Append(Encoding.ASCII.GetString(state.buffer, 0, bytesRead));
                //  Get the rest of the data.
                client.ReceiveTimeout = 500;
                client.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
                    new AsyncCallback(ReceiveCallback), state);
            }
            else
            {
                // All the data has arrived; put it in response.
                if (state.sb.Length > 1)
                {
                    response = state.sb.ToString();
                }
                // Signal that all bytes have been received.
                receiveDone.Set();
            }
        }
        catch (Exception e)
        {
            MessageBox.Show(e.ToString());
        }
    }

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在将当前字符串附加到缓冲区后，应检查值，以便处理消息并删除客户端。ReceiveTimeout=500；我认为这需要时间：

        if (bytesRead > 0)
        {
            state.sb.Append(Encoding.ASCII.GetString(state.buffer, 0, bytesRead));

            response = state.sb.ToString();
            if (response.IndexOf("<EOF>") != -1)
            {
                state.sb.Clear();
                receiveDone.Set();
            }
            else
            {
                client.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
                    new AsyncCallback(ReceiveCallback), state);
            }
        }

---

这只适用于一条消息，对于实时多条消息，我想你应该尝试不同的方法。

你的问题是什么？我想问题很清楚为什么会延迟-我不是100%确定，但你能用你的代码测试SocketFlags。部分标志吗？我怎样才能像同步方法一样快地接收数据？还有如果字节读取>0。。。else{…receiveDone.Set；}看起来有点可疑-你需要一个0字节的读取来设置它，这很可能只有在另一端断开连接的情况下才会发生-或者我猜根据我最后的评论和你的代码，你似乎可以设置receiveDone，只要你读取任何内容，你只需要1个ASCII字符-1字节-那么为什么不在state.sb.Append…之后设置。。。？