22.鼠标单击画蓝色圆点

效果：

package com.lvshitech.gui;

import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.JApplet;

public class MouseEventDemo extends JApplet {
	public void init() {
		// 鼠标事件
		addMouseListener(new CircleListener());
		// 设置背景样式
		setForeground(Color.BLUE);
		setBackground(Color.WHITE);
	}
	
	// 鼠标点击事件实现
	private class CircleListener extends MouseAdapter {
		private int radius = 10;	// 半径
		@Override
		public void mousePressed(MouseEvent e) {	
			JApplet app = (JApplet) e.getSource();
			Graphics g = app.getGraphics();
			g.fillOval(e.getX()-radius, e.getY()-radius, 2*radius, 2*radius);
		}
	}
}