java - udp如何从服务器获取整数？

Question

我将实现一个基于 UDP 的客户端/服务器应用程序，并且我是 Java 世界的新手。服务器在 UDP 协议(protocol)上实现简单的请求-确认协议(protocol)。对于接收到的带有可选参数的字符串标识符(命令)，服务器返回指定的结果。例如，“thread”返回 1 到 5 之间的随机整数，length 返回 5 到 25 之间的随机整数。

问题是我的实现是否正确以及如何解决我的问题(长度 nr 始终在 1 到 5 之间)。我认为我的问题是在服务器类中没有检查 if 语句。是否有其他方法可以将命令发送到服务器，我在这里尝试通过发送字符串然后尝试使用 if 语句进行检查？

这就是我的代码(服务器):

public class server {

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

    DatagramSocket skt;
    try {
        skt = new DatagramSocket(1252);

       byte [] buffer = new byte[1000];

        while(true){
            DatagramPacket request = new DatagramPacket(buffer, buffer.length);
            skt.receive(request);
            String arrayMsg = new String(request.getData());
            System.out.println(arrayMsg);

            //check if the client asks for threadnr
            if(arrayMsg.equals("thread")){
            int threadnumber = (int) (Math.random()*5)+1;
            String threadnum  = Integer.toString(threadnumber);
            byte [] b = threadnum.getBytes();
            DatagramPacket reply = new DatagramPacket(b, b.length, request.getAddress(), request.getPort());
            skt.send(reply);;}

            //check if the client asks for lengthnr
            else if(arrayMsg.equals("length")){
            int lengthnumber = (int) (Math.random()*25)+5;
            String lengthnum = Integer.toString(lengthnumber);
            byte [] b = lengthnum.getBytes();
            DatagramPacket reply = new DatagramPacket(b,  b.length,request.getAddress(), request.getPort());
            skt.send(reply);}           
    }}
    catch (SocketException e) {
        System.out.println("UDP Port 9876 is occupied.");
        System.exit(1);
    }}}

那是我的客户:

public class client {

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

    DatagramSocket skt = new DatagramSocket();
    InetAddress host = InetAddress.getByName("localhost");
    int serverSocket = 1252;
    byte [] senddata = new byte [1000];
    byte [] getdata = new byte[1000];

    //thread send request
    String th = "thread";
    senddata = th.getBytes();
    DatagramPacket requestth = new DatagramPacket(senddata, senddata.length, host, serverSocket);
    skt.send(requestth);

    //thread get reply
    DatagramPacket replyth = new DatagramPacket ( getdata, getdata.length);
    skt.receive(replyth);
    String arrayth = new String(replyth.getData());
    int threadnr=Integer.parseInt(arrayth.trim());          //convert thread string to int and trim it (whitespace)
    System.out.println("Thread received " + threadnr);

    //length send request
    String lg = "length";
    senddata = lg.getBytes();
    DatagramPacket requestlg = new DatagramPacket(senddata, senddata.length, host, serverSocket);
    skt.send(requestlg);

    //length get reply
    DatagramPacket replylg = new DatagramPacket ( getdata, getdata.length);
    skt.receive(replylg);
    String arraylg = new String(replyth.getData());
    int lengthnr=Integer.parseInt(arraylg.trim());          //convert thread string to int and trim it (whitespace)
    System.out.println("Length received " + lengthnr);


    skt.close();

我得到的只是这样的:主题已收到 3收到的长度1

(长度应该在 5 到 25 之间，在我的例子中，它永远不会大于 5)

Answer 1

代码解析第一条消息的响应而不是最后一条消息的响应，因此您会得到随机的 1-5。我建议为变量使用更好的名称，这样您会更快地发现问题。