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Display a simple username/password Dialog from an AppletTag(s): Security


NOTE: This way to authenticate a user is NOT secured at all since the required information is embedded in the Applet.

[MyApplet.java] 

import java.awt.*;
import java.net.*;

public class MyApplet extends java.applet.Applet {

 public String username = "";
 public String password = "";  
   
 public void init() {
   if (!login()) {
     try {
         getAppletContext().showDocument
           (new URL(getCodeBase()+"accessdenied.html"),"_top");
         }
     catch (Exception e) {e.printStackTrace(); }
     }
   else {
     // here the username and password are OK
     }
   }
     
 public boolean login() {
  boolean userValid = false;
  MyLogin login = new MyLogin (new Frame(""));
  requestFocus();
  if (login.id) {
    username = login.username.getText();
    password = login.password.getText();
    userValid = validateUser(username , password);
    System.out.println
      ("The password for " + username 
        +  " is " + (userValid?"valid":"invalid"));
    }
  else
    System.out.println
      ("Cancel was pressed.");
    
  login.dispose();
  return userValid;
  
  }
     
 private boolean validateUser(String usr, String pwd) {
   // here you will code some logic to validate the username
   // password... for testing purpose :
   //                 username = java  password = avaj
   return (usr.equals("java") && pwd.equals("avaj"));
   }
}
[MyLogin.java] 
import java.awt.*;
import java.awt.event.*;

public class MyLogin extends Dialog implements ActionListener {
 boolean id = false;
 Button ok,can;
 TextField username;
 TextField password;


 MyLogin(Frame frame){
  super(frame, "Welcome", true);
  setLayout(new FlowLayout());
  username = new TextField(15);
  password = new TextField(15);
  password.setEchoChar('*');
  add(new Label("User :"));
  add(username);
  add(new Label("Password :"));
  add(password);
  addOKCancelPanel();
  createFrame();
  pack();
  setVisible(true);
  }

 void addOKCancelPanel() {
  Panel p = new Panel();
  p.setLayout(new FlowLayout());
  createButtons( p );
  add( p );
  }

 void createButtons(Panel p) {
  p.add(ok = new Button("OK"));
  ok.addActionListener(this); 
  p.add(can = new Button("Cancel"));
  can.addActionListener(this);
  }

 void createFrame() {
  Dimension d = getToolkit().getScreenSize();
  setLocation(d.width/4,d.height/3);
  }

 public void actionPerformed(ActionEvent ae){
  if(ae.getSource() == ok) {
    id = true;
    setVisible(false);
    }
  else if(ae.getSource() == can) {
    id = false;
    setVisible(false);
    }
  }
}
the HTML to test it out :
[login.html] 
<HTML><HEAD><BODY>
  <TABLE><TR><TD>
  <APPLET CODE=MyApplet.class WIDTH=300 HEIGHT=300>
  </APPLET></TABLE>
  NOTE: View the java console for infos about the login process
  </BODY></HEAD>
</HMTL>
A simple "Access is denied" page :
[accessdenied.html] 
<HTML>
  access is denied
</HMTL>