keylistenerdemo.java

《java事件处理指南》一书的代码,好东西

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class KeyListenerDemo extends JFrame 
{
   private JTextField jtf, jtf2, jtf3, jtf4;

   public KeyListenerDemo()
   {
/*  A JTextField is created and placed on a JFrame.  The JTextField   */
/*  registers a KeyListener.                                          */

      jtf = new JTextField(15);
      jtf.setBorder(BorderFactory.createLineBorder(Color.black));
      jtf.addKeyListener(new KeyHandler());

      jtf2 = new JTextField(12);
      jtf2.setText("key pressed:");
      jtf2.setEditable(false);

      jtf3 = new JTextField(12);
      jtf3.setText("key released:");
      jtf3.setEditable(false);

      jtf4 = new JTextField(12);
      jtf4.setText("key typed:");
      jtf4.setEditable(false);

      JPanel panel = new JPanel();
      panel.add(jtf);

      JPanel panel2 = new JPanel();
      panel2.add(jtf2);
      panel2.add(jtf3);
      panel2.add(jtf4);

      getContentPane().add(panel, BorderLayout.CENTER);
      getContentPane().add(panel2, BorderLayout.SOUTH);

      setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      setBounds(100, 100, 500, 200);
      setVisible(true);
   }

/*  The KeyListener is implemented as an inner class.  For key  */
/*  pressed and key released type KeyEvents, the virtual key    */
/*  code of the keystroke that caused the event is written to   */
/*  a textfield.  Key typed events don't have key code or       */
/*  modifier information, so the character that was typed is    */
/*  written to a textfield.                                     */

   class KeyHandler implements KeyListener
   {
      public void keyPressed(KeyEvent event)
      {
         jtf2.setText("key pressed: "+
                         event.getKeyText(event.getKeyCode()));
      }

      public void keyReleased(KeyEvent event)
      {
         jtf3.setText("key released: "+
                         event.getKeyText(event.getKeyCode()));
      }

      public void keyTyped(KeyEvent event)
      {
         jtf4.setText("key typed: "+
                         event.getKeyChar());
      }
   }

   public static void main(String args[])
   {
      KeyListenerDemo demo = new KeyListenerDemo();
   }
}