java java事件处理机制 event

/* * 功能：java事件处理机制 *  */package com.t; import javax.swing.*;import java.awt.*;import java.awt.event.*;public class Demo2 extends JFrame implements ActionListener{//定义一个panelJPanel mp=null;JButton jb1=null;JButton jb2=null;public static void main(String[] args) {Demo2 demo=new Demo2();}public Demo2(){mp=new JPanel();jb1=new JButton("绿色");jb2=new JButton("红色");this.add(jb1,BorderLayout.NORTH);mp.setBackground(Color.black);this.add(mp);this.add(jb2,BorderLayout.SOUTH);Cat cat1=new Cat();//注册监听jb1.addActionListener(this);//制定action命令jb1.setActionCommand("green");jb2.addActionListener(this);//从jb2.addActionListener(Cat1)就可以看出jb2是事件源，cat1是事件监听对象jb2.addActionListener(cat1);jb2.setActionCommand("red");this.setSize(200,150);this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);this.setVisible(true);}//对时间处理的方法public void actionPerformed(ActionEvent e) {if(e.getActionCommand().equals("red")){System.out.println("你点的是红色按钮");mp.setBackground(Color.red);}else if(e.getActionCommand().equals("green")){System.out.println("你点的是绿色按钮");mp.setBackground(Color.green);}else{System.out.println("不知道");}}}//任何一个类只要实现了相应的接口，就可以去监听某个事件class Cat  implements ActionListener{public void actionPerformed(ActionEvent e) {if(e.getActionCommand().equals("red")){System.out.println("喵喵也知道你点的是红色按钮");}}}//class MyPanel1 extends JPanel//{////public void paint(Graphics g)//{////super.paint(g);//////////}////////}