Question

我是java的新手，我刚创建了两个使用UDP数据包的程序（客户端和服务器）。客户端从用户获取整数并将该数字发送到服务器。然后，服务器从整数中减去2并将其发送回客户端。消息将来回传递，直到客户端从服务器收到非正数。问题是我一直收到相同的号码。有谁知道如何解决这个问题？我需要几个循环吗？

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.nio.ByteBuffer;
import java.util.Scanner;

public class Client {

public static void main (String[] args) throws IOException{

            DatagramSocket ds = new DatagramSocket();

            System.out.println("Insert number: "); 
            Scanner s = new Scanner(System.in);
            int num = s.nextInt();

            int port = 1999;
            byte[] byteSend = ByteBuffer.allocate(4).putInt(num).array();
            InetAddress address = InetAddress.getByName("localhost");
            byte[] byteReceive = new byte[4];
            DatagramPacket dpReceive = new DatagramPacket(byteReceive, byteReceive.length);

                DatagramPacket dpSend = new DatagramPacket(byteSend, byteSend.length, address, port);
                if(num <=0){
                    ds.close();
                }else{

                for(int i = 0; i<=num; i+= 2){
                    ds.send(dpSend);
                    ds.receive(dpReceive);
                    num = ByteBuffer.wrap(byteReceive).getInt();
                    System.out.println("number received: " + num);
                }
                }
                ds.close();
                }               

}

服务器类

import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.nio.ByteBuffer;public class Server {

public static void main(String[] args) throws Exception {

    DatagramSocket dg = new DatagramSocket(1999);

    while(true) {
    System.out.println("Listening");

    byte[] byteReceive = new byte[4];
    DatagramPacket dp = new DatagramPacket(byteReceive, byteReceive.length);
    dg.receive(dp);
    int num = ByteBuffer.wrap(dp.getData()).getInt();

    InetAddress address = dp.getAddress();
    int port = dp.getPort();

    int numResult = num - 2;
    byte[] byteSend = ByteBuffer.allocate(4).putInt(numResult).array();
    DatagramPacket dpSend = new DatagramPacket(byteSend, byteSend.length, address, port);

    System.out.println("number received: " + num);
    System.out.println("number now decreased to: " + numResult);
    dg.send(dpSend);

      }
    }
}

输入6时，客户端的输出如下：

插入号码：

6 收到的数字：4

收到的数字：4

服务器的输出如下：

听力

收到的数字：6

现在减少到：4

听力

Answer 1

客户端不断发送相同的号码。您永远不会更新dpSend。

只获取相同的udp数据包

1 个答案: