使用UDP的Java套接字編程

Question

我正在嘗試使用服務器客戶端發送一些數字和哈希。 我正在使用UDP協議來這樣做。 我按照預期的那樣使用數字或哈希值創建了一個數據包，並使用套接字發送了它。 客戶收到它，因此，只打印接收到的值。 但是，當我在客戶端收到數字和哈希值時，我不會得到相同的結果。 可能是什么問題？

我正在提供服務器和客戶端代碼以及到達此處的輸出。

服務器代碼：

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.nio.charset.StandardCharsets;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.util.ArrayList;
import javax.xml.bind.DatatypeConverter;

public class main {

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

        int n = 10;
        SecureRandom rand = new SecureRandom();
        ArrayList<String> clue = new ArrayList<String>();
        ArrayList<String> cluenum = new ArrayList<String>();
        MessageDigest digestnew = MessageDigest.getInstance("SHA-256");
        byte[] finalmsgblock = "End".getBytes();

        for(int i = 0; i < n; i++)
        {
            int num = rand.nextInt(100);
            String num1 = Integer.toString(num);
            byte[] num2 = digestnew.digest(num1.getBytes(StandardCharsets.UTF_8));
            String num3 = "Clue: " + DatatypeConverter.printHexBinary(num2);
            clue.add(i,num3);
            cluenum.add(i, num1);

        }
        System.out.println(clue);
        System.out.println(cluenum);

        // Create a Socket
        DatagramPacket packet, packet1;
        InetAddress address;
        DatagramSocket socket;
        socket = new DatagramSocket();
        address = InetAddress.getByName("127.0.0.1");

        for(int i = 0; i < n; i++)
        {
            byte[] newdata = clue.get(i).getBytes(StandardCharsets.UTF_8);
            packet = new DatagramPacket (newdata, newdata.length, address, 1502);
            socket.send(packet);
            System.out.println("Sent clue!");

            byte[] newdata1 = cluenum.get(i).getBytes(StandardCharsets.UTF_8);
            packet1 = new DatagramPacket (newdata1, newdata1.length, address, 1502);
            socket.send(packet1);
            System.out.println("Sent cluenum!");
        }

        DatagramPacket  packet11 = new DatagramPacket (finalmsgblock, finalmsgblock.length, address, 1502);
        socket.send(packet11);

    }

}

客戶代碼：

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.nio.charset.StandardCharsets;
import java.security.SecureRandom;
import java.util.ArrayList;
import javax.xml.bind.DatatypeConverter;

public class main {

    public static void main(String[] args) throws IOException {
        int n = 10;
        SecureRandom rand = new SecureRandom();
        ArrayList<String> clue = new ArrayList<String>();
        ArrayList<String> cluenum = new ArrayList<String>();

        // Create the socket
        int port = 1502;
        DatagramSocket socket;
        byte[] buf = new byte[10000];
        DatagramPacket packet = new DatagramPacket(buf, buf.length);
        InetAddress address = InetAddress.getByName("127.0.0.1");
        socket = new DatagramSocket(port, address);
        int i1 = 0;
        int i2 = 0;

        while(true)
        {
            socket.receive (packet);
            byte[] data = new byte[packet.getLength()];
            System.arraycopy(packet.getData(), packet.getOffset(), data, 0, packet.getLength());
            String n1 = new String(data);
            if(new String(data).equals("End"))
            {
                break;
            }
            else
            {
                if(n1.startsWith("Clue: "))
                {
                    String n2 = (n1.replace("Clue: ", ""));
                    byte[] num = n2.getBytes(StandardCharsets.UTF_8);
                    String num1 = DatatypeConverter.printHexBinary(num);
                    clue.add(i1, num1);
                    i1 = i1 + 1;
                }
                else
                {
                    byte[] num = n1.getBytes(StandardCharsets.UTF_8);
                    String num1 = DatatypeConverter.printHexBinary(num);
                    cluenum.add(i2, num1);
                    i2 = i2 + 1;
                }
            }
        }

        System.out.println(clue);
        System.out.println(cluenum);
    }

}

我得到的輸出如下：

服務器輸出：

[Clue: BBB965AB0C80D6538CF2184BABAD2A564A010376712012BD07B0AF92DCD3097D, 
 Clue: 44C8031CB036A7350D8B9B8603AF662A4B9CDBD2F96E8D5DE5AF435C9C35DA69,
 Clue: 6E4001871C0CF27C7634EF1DC478408F642410FD3A444E2A88E301F5C4A35A4D, 
 Clue: A46E37632FA6CA51A13FE39A567B3C23B28C2F47D8AF6BE9BD63E030E214BA38,                 
 Clue: C837649CCE43F2729138E72CC315207057AC82599A59BE72765A477F22D14A54,    
 Clue: CD70BEA023F752A0564ABB6ED08D42C1440F2E33E29914E55E0BE1595E24F45A, 
 Clue: 7902699BE42C8A8E46FBBB4501726517E86B22C56A189F7625A6DA49081B2451, 
 Clue: 19581E27DE7CED00FF1CE50B2047E7A567C76B1CBAEBABE5EF03F7C3017BB5B7, 
 Clue: EF2D127DE37B942BAAD06145E54B0C619A1F22327B2EBBCFBEC78F5564AFE39D, 
 Clue: 1A6562590EF19D1045D06C4055742D38288E9E6DCD71CCDE5CEE80F1D5A774EB]
 [83, 84, 93, 82, 57, 89, 7, 9, 5, 50]

客戶端輸出：[42424239363541423043383044363533384346323138344241424144324135363441303130333736373132303132424430374230414639324443443330393744，34344338303331434230333641373335304438423942383630334146363632413442394344424432463936453844354445354146343335433943333544413639，36453430303138373143304346323743373633344546314443343738343038463634323431304644334134343445324138384533303146354334413335413444，41343645333736333246413643413531413133464533394135363742334332334232384332463437443841463642453942443633453033304532313442413338，43383337363439434345343346323732393133384537324343333135323037303537414338323539394135394245373237363541343737463232443134413534，43443730424541303233463735324130353634414242364544303844343243313434304632453333453239393134453535453042453135393545323446343541，37393032363939424534324338413845343646424242343530313732363531374538364232324335364131383946373632354136444134393038314232343531，31393538314532374445374345443030464631434535304232303437453741353637433736 423143424145424142453543033033743743333031374242354237，45463244313237444533374239343242414144303631343545544342544336944314944323374374232454242454242434542544337384635353634414645333944，3141363536323539304546313946313044354430364,30353537343343343343 3834 3873374354 374374354

我嘗試過，但無法格式化客戶端輸出

編輯：我試圖只發送數字，它仍然無法正常工作。 請讓我知道可能是什么問題？

Answer 1

您正在從服務器發送十六進制編碼的數據。 然后，您的客戶端不應再次使用DatatypeConverter.printHexBinary(num)轉換該十六進制

代替客戶做

   String n2 = (n1.replace("Clue: ", ""));
   byte[] num = n2.getBytes(StandardCharsets.UTF_8);
   String num1 = DatatypeConverter.printHexBinary(num);
   clue.add(i1, num1);

做就是了

 String n2 = (n1.replace("Clue: ", ""));
 clue.add(i1, n2);

（並且在客戶端的else子句中也進行類似操作。）