java UDP程序包丢失跟踪

Question

为了实现可靠的连接，必须使用TCP

但是，我想知道是否有办法修改我的代码，以便在UDP中检查丢失的数据包

 try {
        DatagramSocket socket = new DatagramSocket(5000);

        while(true) {
            byte[] buffer = new byte[50];
            DatagramPacket packet = new DatagramPacket(buffer, buffer.length);
            socket.receive(packet);
            System.out.println("Text received is: " + new String(buffer, 0, packet.getLength()));

            String returnString = "echo: " + new String(buffer, 0, packet.getLength());
            byte[] buffer2 = returnString.getBytes();
            InetAddress address = packet.getAddress();
            int port = packet.getPort();
            packet = new DatagramPacket(buffer2, buffer2.length, address, port);
            socket.send(packet);
        }

    } catch(SocketException e) {
        System.out.println("SocketException: " + e.getMessage());
    } catch(IOException e) {
        System.out.println("IOException: " + e.getMessage());
    }
}

Answer 1

由于传输协议不提供设施，应用程序协议需要这样做

例如，您可以让发送方在每条消息中添加一个序列号，然后接收方就会知道某个数据报已丢失或（也可能）重复

这可以让你发现损失，但却无法让你从中恢复过来

当然，你需要在接收器中跟踪每个发送者的预期序列号