Question

这是我正在谈论的简单UDP server。

我们如何检查通过客户端发送的字符串是否与收到的字符串相同？我尝试了一个简单的if条件来检查它们是否相等，使用了字符串的equal（）方法，但即使消息是相同的，if条件结果为false，即使使用.toString（）比较发送和接收的消息方法。

import java.net.*;
import java.io.*;
import java.util.Arrays;

public class UDPClient {
public static void main(String args[]) throws Exception
   {
      BufferedReader inFromUser =
         new BufferedReader(new InputStreamReader(System.in));
      DatagramSocket clientSocket = new DatagramSocket();
      InetAddress IPAddress = InetAddress.getByName("localhost");
      byte[] sendData = new byte[1024];
      byte[] receiveData = new byte[1024];
      String sentence = inFromUser.readLine();
      sendData = sentence.getBytes();
      DatagramPacket sendPacket = new DatagramPacket(sendData, sendData.length, IPAddress, 7777);
      clientSocket.send(sendPacket);
      DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length);
      clientSocket.receive(receivePacket);
      String sentSentence = new String(sendPacket.getData());
      String receivedSentence = new String(receivePacket.getData());
      System.out.println("FROM SERVER:" + receivedSentence + "\n" + "IP Address: " + receivePacket.getAddress() + "\n" +
              "Message Size: " + receivePacket.getData().length);
      clientSocket.close();
      System.out.println(sentSentence + " " + receivedSentence);

       if(sentSentence.equals(receivedSentence.toString()))
        System.out.println("OK" + " " + sentence + " " + receivedSentence);
       else
           System.out.println("FAILED");

   }
}

Answer 1

String sentSentence = new String(sendPacket.getData());
String receivedSentence = new String(receivePacket.getData());

正如预期的那样，您无法正确构建这些Strings。它应该是：

String sentSentence = new String(sendPacket.getData(), sendPacket.getOffset(), sendPacket.getLength());
String receivedSentence = new String(receivePacket.getData(), receivePacket.getOffset(), receivePacket.getLength());

如何检查发送的消息是否与简单UDP服务器中收到的消息相同

1 个答案: