一个必看的Java程序

//程序名 :TelnetApp.Java

 import java.applet.*;
 import java.awt.*;
 import java.io.*;
 import java.net.*;
 import java.util.*;

 public class TelnetApp extends Applet implements Runnable
 {
   //声明成员变量

   Thread client;
   TextArea log;

   TextField hostname;
   TextField userid;
   TextField password;
   Label hname;
   Label uid;
   Label psd;
  
   Button connect;
   Button bye;

   int wantTime;
   boolean logged;
   
   Socket socket =null;
   PrintStream os;
   DataInputStream is;

   public TelnetApp()
   {
     resize(400,300);
     setLayout(new BorderLayout());
     Panel p1=new Panel();
     log =new TextArea(10,80);
     log.setEditable(true);
     p1.add(log);
     add("North",p1);

     Panel p2=new Panel();
       p2.add(hname=new Label("Hostname"));
       p2.add(hostname =new TextField(20));
     p2.add(uid= new Label("Userid:"));
     p2.add(userid =new TextField(10));
     p2.add(psd =new Label("Password:"));
     p2.add(password =new TextField(10));
     password.setEchoCharacter('*');

     add("Center",p2);

     Panel p3=new Panel();
     p3.add(connect =new Button("Connect"));
     p3.add(bye =new Button("Bye"));
     bye.disable();
     add("South",p3);

     logged = false;                                                                                          
   }

   public void run()
   {
     String fromServer=null;
     byte b[]=new byte[3];
     b[0]=(byte)'n';
     while(true){
                if((fromServer =getDate())!= null)
                   log.appendText(fromServer +"\n");
                          if(wantTime <0){
                                  bye();
                                  break;
                                         }
                if(logged){
                   delay(60*1000);
                   log.setText(" ");
                   wantTime -= 1;
                   sendData(b,1);
                   }
     }
   }

   //建立主机连接

    private boolean connectHost(String hostName)
    {
      try{
      socket =new Socket(hostName,23);
      os =new PrintStream(socket.getOutputStream());
      is =new DataInputStream(socket.getInputStream());
     }