UDP的C# BeginReceive

Question

我正在努力学习如何将BeginReceive用于UDP，下面是我所拥有的：

        Console.WriteLine("Initializing SNMP Listener on Port:" + port + "...");
        UdpClient client = new UdpClient(port);
        //UdpState state = new UdpState(client, remoteSender);


        try
        {
          client.BeginReceive(new AsyncCallback(recv), null);
        }
        catch (Exception e)
        {
            Console.WriteLine(e);
        }


    }

    private static void recv(IAsyncResult res)
    {
        int port = 162;
        UdpClient client = new UdpClient(port);
        IPEndPoint RemoteIpEndPoint = new IPEndPoint(IPAddress.Any, 162);
        byte[] received = client.EndReceive(res, ref RemoteIpEndPoint);
        Console.WriteLine(Encoding.UTF8.GetString(received));
        client.BeginReceive(new AsyncCallback(recv), null);

    }

什么都没有发生，代码结束时甚至不调用recv方法。那是为什么？

编辑

加:-

   Console.ReadLine();

现在它给了我一个例外，在下面一行：

 Only one usage of each socket address is normally permitted. 

试过:-

       try
        {
          client.BeginReceive(new AsyncCallback(recv), client);
        }

    private static void recv(IAsyncResult res)
    {
    //    int port = 162;

        try
        {
            IPEndPoint RemoteIpEndPoint = new IPEndPoint(IPAddress.Any, 162);
            byte[] received = res.AsyncState.EndReceive(res, ref RemoteIpEndPoint);
            Console.WriteLine(Encoding.UTF8.GetString(received));
            res.AsyncState.BeginReceive(new AsyncCallback(recv), null);

        }

        catch (Exception e)
        {
            Console.WriteLine(e);

        }

错误：

'object' does not contain a definition for 'EndReceive' and no extension method 'EndReceive' accepting a first argument of type 'object' could be found (are you missing a using directive or an assembly reference?)

Answer 1

如果代码的第一部分本质上是您的主要函数的主体，那么您不应该对它的结束感到惊讶。放一个

Console.Readline();

在关闭} of main之前等待。

一旦一些数据到达，recv将被异步调用。然后，您需要从等待的UDP客户端读取接收的数据。为了访问这个客户机，您将通过BeginReceive的状态参数传递它

client.BeginReceive(new AsyncCallback(recv), client);

并最终从回调IAsyncResult参数获得它。

UdpClient client = (UdpClient)res.AsyncState;

在类字段中存储客户机可能更容易(但不那么灵活)。

现在您可以从

byte[] received = client.EndReceive(res, ref RemoteIpEndPoint);