salut
je suis débutant en langage Java et je suis entrain d'apprendre de jour en jour a programmer cependant sur mes recherches j'ai trouvé une Classe java sur Web que je n'arrive pas a comprendre , il ne s' agit pas de copier coller mais je veut juste comprendre cette Classe
il s'agit de la Classe suivante Chat Server programmer pour creer un serveur d'une application :

je veut juste comprendre comment elle marche ?
Code : Sélectionner tout - Visualiser dans une fenêtre à part
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import java.net.*;
 
   import java.text.SimpleDateFormat;
   import java.util.Date;
   import java.util.Locale;
   import java.util.regex.Matcher;
   import java.util.regex.Pattern;
 
   public class ChatServer {
 
       DatagramSocket ds;
 
       byte[] recbuf = new byte[1024];
 
       DatagramPacket rec = new DatagramPacket(recbuf, recbuf.length);
 
       int port;
 
       String newAddress = "";
       String addressList = "";
       String sendAddressList = "";
 
       public ChatServer(int port) {
           this.port = port;
       }
 
       public void init() throws Exception {//DatagramSocket
           if (port < 1024 || port > 65535) {
               System.out.println("initialisation du port a la valeur 2008 ");
               ds = new DatagramSocket(2008);
           } else {
               ds = new DatagramSocket(port);
           }
       }
 
       public void start() throws Exception {
           println("demarrage du port");
           println("valeur du port" + port);
           init();
           receive();
       }
 
       public void receive() {
           for ( ; ; ) {
               try {
                   ds.receive(rec);
 
                   String msg = new String(rec.getData(), rec.getOffset(), rec.getLength());
                   String natAddress = rec.getAddress().toString().substring(1);
                   int natPort = rec.getPort();
 
                   String Num = msg.substring(0,1);
                   msg = msg.substring(2);
                   String line;
 
                   switch(Integer.parseInt(Num)){//
                       case 1 : {
                           line = "Ò»¸öеÄÓû§µÇ¼: " + msg + "  NATµØÖ·: " + natAddress + " ¹ÜÀí¶Ë¿Ú: " + natPort;
                           sendAddressList = sendAddressList + natAddress + " " + natPort + " ";
                           newAddress = msg + ":" + natAddress + ":" + natPort;
                           println(line);
                           break;
                       }
 
                       case 2 : {
                           line = "ÒôƵ¶Ë¿Ú: " + natPort;
                           newAddress = newAddress + ":" + natPort;
                           println(line);
                           break;
                       }
 
                       case 3 : {
                           line = "ÒôƵRTCP¶Ë¿Ú: " + natPort;
                           newAddress = newAddress + ":" + natPort;
 
                           println(line);
                           break;
 
                       }
 
                       case 4 : {
                           line = "ÊÓƵ¶Ë¿Ú: " + natPort;
                           newAddress = newAddress + ":" + natPort;
 
                           println(line);
                           break;
                       }
 
                       case 5 : {
                           line = "ÊÓƵRTCP¶Ë¿Ú: " + natPort;
                           newAddress = newAddress + ":" + natPort;
                          println(line);
                          if (!sendAddressList.equals(""))
                              doSend("1 " + newAddress, sendAddressList);
                          if(!addressList.equals("")){
                              String address[] = newAddress.split(":");
                              doSend("7 " + addressList,
                                     address[1] + " " + address[2]);
                          }
                          addressList = addressList + newAddress + " ";
                          break;
                      }
 
                      case 6 : {
                          line = "Ò»¸ö¿Í»§À뿪: " + msg + "  NATµØÖ·: " + natAddress + " ¹ÜÀí¶Ë¿Ú: " + natPort;
                          println(line);
                          delAddress(msg, natAddress, natPort);
                          if(!sendAddressList.equals(""))
                              doSend("6 " + msg + ":" + natAddress, sendAddressList);
                          break;
                      }
 
                      case 7 : break;
                  }
 
              } catch (Exception e) {
                  e.printStackTrace();
              }
          }
      }
 
      public void doSend(String msgSend, String sendAddressList) throws Exception {
          String[] s = sendAddressList.split(" ");
          byte[] data = msgSend.getBytes();
          for(int i =0; i < s.length; i++){
              DatagramPacket pack = new DatagramPacket(data, data.length, InetAddress.getByName(s[i]), Integer.parseInt(s[++i]));
              ds.send(pack);
          }
      }
 
      public void delAddress(String msg, String natAddress, int ctrlPort){
 
          String regEx = msg + ":" + natAddress + ":" + ctrlPort + ":.{1,5}:.{1,5}:.{1,5}:.{1,5} ";
          Pattern p = Pattern.compile(regEx);
          Matcher m=p.matcher(addressList);
 
          String s = m.replaceAll("");
          addressList = s;
 
          regEx = natAddress + " " + ctrlPort + " ";
          p = Pattern.compile(regEx);
          m = p.matcher(sendAddressList);
          s = m.replaceAll("");
          sendAddressList = s;
      }
 
      public void println(String s) {
          Date nowTime = new Date();
          SimpleDateFormat fmt = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss aa", Locale.US);
          System.out.println(fmt.format(nowTime) + "----" + s);
      }
 
      public static void main(String[] args) throws Exception {
          new ChatServer(2008).start();
      }
  }