学步园

java.awt.event.MouseAdapter    java.awt.event.KeyAdapter    java.awt.event.WindowAdapter 等等都是适配器模式

//  运行适配器的例子

public class TwoListennerAdapter {

    private Frame frame;
 
 private TextField textField;
 
 public static void main(String[] args) {
      
  TwoListen twoListen = new TwoListen();
  
  twoListen.go();

 }
 
    public void go(){
  
  frame = new Frame("two listenners example");
  
  frame.add(new Label("click"),BorderLayout.NORTH);
  
  textField = new TextField();
  
  frame.add(textField,BorderLayout.SOUTH);

  //  增加一个鼠标的监听  
  frame.addMouseListener(new MyAdapter());
  
  frame.setSize(300,200);
  
  frame.setVisible(true);
 }

}

//  继承这个适配器后，就不需要实现鼠标所有的方法，由适配器帮你实现了

class MyAdapter extends MouseAdapter{
 @Override
 public void mouseEntered(MouseEvent e) {
  System.out.println("--enter--");
 }
 @Override
 public void mouseExited(MouseEvent e) {
  System.out.println("--exit--");
 }
}

//  jdk的源码MouseAdapter,原理就是做了很多空的实现

public abstract class MouseAdapter implements MouseListener, MouseWheelListener, MouseMotionListener {
    /**
     * {@inheritDoc}
     */
    public void mouseClicked(MouseEvent e) {}

    /**
     * {@inheritDoc}
     */
    public void mousePressed(MouseEvent e) {}

    /**
     * {@inheritDoc}
     */
    public void mouseReleased(MouseEvent e) {}

    /**
     * {@inheritDoc}
     */
    public void mouseEntered(MouseEvent e) {}

    /**
     * {@inheritDoc}
     */
    public void mouseExited(MouseEvent e) {}

    /**
     * {@inheritDoc}
     * @since 1.6
     */
    public void mouseWheelMoved(MouseWheelEvent e){}

    /**
     * {@inheritDoc}
     * @since 1.6
     */
    public void mouseDragged(MouseEvent e){}

    /**
     * {@inheritDoc}
     * @since 1.6
     */
    public void mouseMoved(MouseEvent e){}
}