Question

我试图使用C sharp创建一个简单的UDP应用程序，没有复杂，连接，发送一些文本，并接收它！但它一直在抛出这个例外！

“远程主机强行关闭现有连接”！

代码：

     byte[] data = new byte[1024];
    IPEndPoint ipep = new IPEndPoint(IPAddress.Parse("127.0.0.1"), 9050);

    Socket server = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);

    string welcome = "Hello, are you there?";
    data = Encoding.ASCII.GetBytes(welcome);
    server.SendTo(data, data.Length, SocketFlags.None, ipep);

    IPEndPoint sender = new IPEndPoint(IPAddress.Any, 0);
    EndPoint tmpRemote = (EndPoint)sender;

   data = new byte[1024];
    int recv = server.ReceiveFrom(data, ref tmpRemote);

    Console.WriteLine("Message received from {0}:", tmpRemote.ToString());
    Console.WriteLine(Encoding.ASCII.GetString(data, 0, recv));



    Console.WriteLine("Stopping client");
    server.Close();

thanks =）

Answer 1

在调用Receive之前，您应该告诉系统您正在侦听端口9050上的UDP数据包。在server.Bind(ipep);

之后添加Socket server = new Socket(...);

Answer 2

您是否尝试检查IP地址是否有效且该端口未用于其他内容？

<强>窗：

开始＆gt;运行＆gt; “cmd”＆gt; “ipconfig”。

Answer 3

尝试关闭防火墙软件。

Answer 4

如果您不知道应答服务器的IP，最好： recv = server.Receive(data);

以下是我对您的代码的建议。你可以使用一个使用条件的do-while循环（在我的例子中它是一个无限循环）：

        byte[] data = new byte[1024];
        IPEndPoint ipep = new IPEndPoint(IPAddress.Parse("127.0.0.1"), 9050);

        Socket server = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);

        string welcome = "Hello, are you there?";
        data = Encoding.ASCII.GetBytes(welcome);
        server.ReceiveTimeout = 10000; //1second timeout
        int rslt =  server.SendTo(data, data.Length, SocketFlags.None, ipep);

        data = new byte[1024];
        int recv = 0;
        do
        {
            try
            {
                Console.WriteLine("Start time: " + DateTime.Now.ToString());
                recv = server.Receive(data); //the code will be stoped hier untill the time out is passed
            }
            catch {  }
        } while (true); //carefoul! infinite loop!

        Console.WriteLine(Encoding.ASCII.GetString(data, 0, recv));
        Console.WriteLine("Stopping client");
        server.Close();

C＃中的UDP客户端

4 个答案: