hiereventdemo.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 HierEventDemo extends JFrame
{
   private JButton button;
   private int frameInitWidth, frameInitHeight;
   private int buttonInitWidth, buttonInitHeight;

   public HierEventDemo()
   {
      buttonInitWidth = 70;
      buttonInitHeight = 70;
      frameInitWidth = 300;
      frameInitHeight = 200;

/*  A JButtons is placed on a JFrame.  The button registers   */
/*  a HierarchyBoundsListener.                                */

      button = new JButton("Button");
      button.setPreferredSize(
              new Dimension(buttonInitWidth, buttonInitHeight));
      button.setBorder(BorderFactory.createRaisedBevelBorder());
      button.addHierarchyBoundsListener(new HierBndsListener());

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

      getContentPane().add(panel);

      setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      setBounds(100, 100, frameInitWidth, frameInitHeight);
      setVisible(true);
   }

/*  A HierarchyBoundsListener is implemented as an inner class that    */
/*  extends the HierarchyBoundsAdapter class.  If the frame is         */
/*  re-sized, HierarchyEvents generated by the button are sent to the  */
/*  ancestorResized() method.  This method resizes the button so its   */
/*  size relative to the frame remains the same.                       */

   class HierBndsListener extends HierarchyBoundsAdapter
   {
      public void ancestorResized(HierarchyEvent event)
      {
         Component top = event.getChanged();
         JButton source = (JButton)event.getComponent();

         int width = top.getWidth();
         int height = top.getHeight();

         source.setPreferredSize(
              new Dimension(buttonInitWidth*width/frameInitWidth, 
                            buttonInitHeight*height/frameInitHeight));
      }
   }

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