java事件监听示例

一、Button 监听示例

package com.text01;

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


// 实现接口
public class Demo8_0 extends JFrame implements ActionListener{
	
	JPanel mp = null;
	JButton jb1 = null;
	JButton jb2 = null;
	public static void main(String[] args) {
		// TODO 自动生成的方法存根
		Demo8_0 demo8_0 = new Demo8_0();
	}

	public Demo8_0(){
		mp = new JPanel();
		jb1 = new JButton("Black");
		jb2 = new JButton("Red");
		
		this.add(jb1, BorderLayout.NORTH);
		mp.setBackground(Color.red);
		this.add(mp);
		this.add(jb2, BorderLayout.SOUTH);
		
		// Register Listener
		jb1.addActionListener(this);
		// action 
		jb1.setActionCommand("Black");
		jb2.addActionListener(this);
		jb2.setActionCommand("Red");
		
		this.setSize(200, 150);
		this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);;
		this.setVisible(true);
	}

	//对事件处理的方法
	@Override
	public void actionPerformed(ActionEvent arg0) {
		// TODO 自动生成的方法存根
		System.out.println("Button clicked");
		// judge which button is clicked.
		if(arg0.getActionCommand().equals("Black")){
			System.out.println("Black button is clicked");
			mp.setBackground(Color.BLACK);
		}
		else if(arg0.getActionCommand().equals("Red")){
			System.out.println("Red button is clicked");
			mp.setBackground(Color.RED);
		}
		else{
			System.out.println("Not know");
		}
	}
}

运行效果：（按下“Black”，面板颜色变成黑色，按下“Red”，变成红色）

二、键盘key监听示例

package com.text01;

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

public class Demo8_10 extends JFrame {
	
	MyPanel mp = null;
	public static void main(String[] args) {
		// TODO 自动生成的方法存根
		Demo8_10 demo8_10 = new Demo8_10();
	}

	public Demo8_10(){
		mp = new MyPanel();
		this.add(mp);
		
		this.addKeyListener(mp);
		this.addKeyListener(mp);
		
		this.setSize(400, 300);
		this.setVisible(true);
	}
}

class MyPanel extends JPanel implements KeyListener{
	
	int x = 10;
	int y = 10;
	
	public void paint(Graphics g){
		super.paint(g);
		g.fillOval(x, y, 10, 10);
	}

	@Override
	public void keyPressed(KeyEvent arg0) {
		// TODO 自动生成的方法存根
//		System.out.println("Key is pressed." + (char)arg0.getKeyCode());
		if(arg0.getKeyCode() == KeyEvent.VK_DOWN){
			y++;
		}
		if(arg0.getKeyCode() == KeyEvent.VK_UP){
			y--;
		}
		
		if(arg0.getKeyCode() == KeyEvent.VK_LEFT){
			x--;
		}
		
		if(arg0.getKeyCode() == KeyEvent.VK_RIGHT){
			x++;
		}
		
		this.repaint();
		
	}

	@Override
	public void keyReleased(KeyEvent arg0) {
		// TODO 自动生成的方法存根
		
	}

	@Override
	public void keyTyped(KeyEvent arg0) {
		// TODO 自动生成的方法存根
		
	}
}

运行效果：（按动键盘上下左右键，小球会上下左右相应移动）