Java---实力弹弹球，弹弹弹

package cn.hncu.threadDemo.thread2;

import java.awt.Canvas;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.FocusEvent;
import java.awt.event.FocusListener;

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JSpinner;
import javax.swing.Timer;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;

public class BallsJFrame extends JFrame implements ChangeListener{
private BallsCanvas ball;
private JSpinner spinner;

public BallsJFrame(){
super("弹弹球");
this.setBounds(300, 200, 400, 300);
this.setDefaultCloseOperation(EXIT_ON_CLOSE);
Color colors[] = {Color.red,Color.green,Color.blue,Color.magenta,Color.cyan};

ball = new BallsCanvas(colors,100);
this.getContentPane().add(ball);//默认是CENTER位置

JPanel panel = new JPanel();
this.getContentPane().add(panel,"South");
panel.add(new JLabel("Delay"));
spinner = new JSpinner();
spinner.setValue(100);

panel.add(spinner);

spinner.addChangeListener(this);

this.setVisible(true);
}
@Override
public void stateChanged(ChangeEvent e) {
int value = Integer.parseInt(""+spinner.getValue());
ball.setDelay(value);
}

public static void main(String[] args) {
new BallsJFrame();
}

}

class BallsCanvas extends Canvas implements ActionListener, FocusListener{
private Ball balls[];//存放所有的球
private Timer timer;//javax.swing.Timer

public BallsCanvas(Color colors[] ,int delay){
this.balls = new Ball[colors.length];
for(int i=0,x=40;i<colors.length;i++,x+=20){
this.balls[i] = new Ball(x,x,colors[i]);

}

//让当前画布监听 焦点事件
this.addFocusListener(this);

timer = new Timer(delay,this);
timer.start();

}

public void setDelay(int delay){
timer.setDelay(delay);
}

@Override
public void paint(Graphics g) {
for(int i=0;i<this.balls.length;i++){
g.setColor(balls[i].color);

//让每个球的坐标变化一下---（x坐标）
balls[i].x = balls[i].left ? balls[i].x-10:balls[i].x+10;
//当球碰壁时，更改球的方向
if(balls[i].x<=0||balls[i].x>=this.getWidth()-24){
balls[i].left = !balls[i].left;//切换方向
}

//让每个球的坐标变化一下---（y坐标）
balls[i].y = balls[i].up ? balls[i].y-10:balls[i].y+10;
//当球碰壁时，更改球的方向
if(balls[i].y<=0||balls[i].y>=this.getHeight()-22){
balls[i].up = !balls[i].up;//切换方向
}

g.fillOval(balls[i].x, balls[i].y, 20, 20);
}
}

@Override
public void actionPerformed(ActionEvent e) {
//System.out.println("aaa");
repaint();//刷新画布.调用paint(Graphics g)
}

@Override
public void focusGained(FocusEvent e) {
timer.stop();
}

@Override
public void focusLost(FocusEvent e) {
timer.restart();

}

private static class Ball{
int x,y;
boolean up,left;
Color color;
public Ball(int x, int y, Color color) {
this.x = x;
this.y = y;
this.color = color;
up = left = false;
}

}

}