Java---实力弹弹球，弹弹弹

直接上代码了。

微调按钮加画布画几个圆，再实现监听。。。

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;

        }

    }

}