疯狂java实战演义 弹球游戏代码

 package org.crazyit.ball;

 import java.awt.Image;
 import java.io.File;
 import javax.imageio.ImageIO;
 import java.io.IOException;

 /**
  * 小球对象
  *
  * @author yangenxiong [e-mail]
  * @author Kelvin Mak [e-mail]
  * @version  1.0
  * <br/>网站: <a href="http://www.crazyit.org">疯狂Java联盟</a>
  * <br>Copyright (C), 2009-2010, yangenxiong
  * <br>This program is protected by copyright laws.
  */
 public class Ball extends BallComponent {
     // 定义球的竖向速度
     private int speedY = 10;
     // 定义弹球的横向速度
     private int speedX = 8;
     // 定义是否在运动
     private boolean started = false;
     // 定义是否结束运动
     private boolean stop = false;

     /**
      * m 有参数构造器
      *
      * @param panelWidth
      *            int 画板宽度
      * @param panelHeight
      *            int 画板高度
      * @param offset
      *            int 位移
      * @param path
      *            String 图片路径
      */
     public Ball(int panelWidth, int panelHeight, int offset, String path)
             throws IOException {
         // 调用父构造器
         super(panelWidth, panelHeight, path);
         // 设置y坐标
         this.setY(panelHeight - super.getImage().getHeight(null) - offset);
     }

     /**
      * 设置横向速度
      *
      * @param speed
      *            int 速度
      * @return void
      */
     public void setSpeedX(int speed) {
         this.speedX = speed;
     }

     /**
      * 设置竖向速度
      *
      * @param speed
      *            int 速度
      * @return void
      */
     public void setSpeedY(int speed) {
         this.speedY = speed;
     }

     /**
      * 设置是否在运动
      *
      * @param b
      *            boolean
      * @return void
      */
     public void setStarted(boolean b) {
         this.started = b;
     }

     /**
      * 设置是否结束运动
      *
      * @param b
      *            boolean
      * @return void
      */
     public void setStop(boolean b) {
         this.stop = b;
     }

     /**
      * 返回横向速度
      *
      * @return int 速度
      */
     public int getSpeedX() {
         return this.speedX;
     }

     /**
      * 返回竖向速度
      *
      * @return int 速度
      */
     public int getSpeedY() {
         return this.speedY;
     }

     /**
      * 是否在运动
      *
      * @return boolean 是否在运动
      */
     public boolean isStarted() {
         return this.started;
     }

     /**
      * 是否已经结束运动
      *
      * @return boolean 是否已经结束运动
      */
     public boolean isStop() {
         return this.stop;
     }

 }

Ball

 package org.crazyit.ball;

 import java.awt.Image;
 import java.io.File;
 import javax.imageio.ImageIO;
 import java.io.IOException;

 /**
  * 桌面弹球游戏相关组件的父类
  *
  * @author yangenxiong [e-mail]
  * @author Kelvin Mak [e-mail]
  * @version  1.0
  * <br/>网站: <a href="http://www.crazyit.org">疯狂Java联盟</a>
  * <br>Copyright (C), 2009-2010, yangenxiong
  * <br>This program is protected by copyright laws.
  */
 public class BallComponent {
     // 设置x坐标
     private int x = -1;
     // 设置y坐标
     private int y = -1;
     // 设置图片
     private Image image = null;
     // 设置图片速度
     private int speed = 5;

     /**
      * 构造器
      *
      * @param path
      *            String 图片路径
      */
     public BallComponent(String path) throws IOException {
         super();
         this.image = ImageIO.read(new File(path));
     }

     /**
      * 构造器
      *
      * @param panelWidth
      *            int 画板宽度
      * @param panelHeight
      *            int 画板高度
      * @param path
      *            String 图片路径
      */
     public BallComponent(int panelWidth, int panelHeight, String path)
             throws IOException {
         super();
         // 读取图片
         this.image = ImageIO.read(new File(path));
         // 设置x坐标
         this.x = (int) ((panelWidth - image.getWidth(null)) / 2);
     }

     /**
      * 构造器
      *
      * @param x
      *            int 图像的x坐标
      * @param y
      *            int 图像的y坐标
      * @param path
      *            String 图片路径
      */
     public BallComponent(String path, int x, int y) throws IOException {
         super();
         // 读取图片
         this.image = ImageIO.read(new File(path));
         this.x = x;
         this.y = y;
     }

     /**
      * 获取x坐标
      *
      * @return int x坐标
      */
     public int getX() {
         return this.x;
     }

     /**
      * 获取y坐标
      *
      * @return int y坐标
      */
     public int getY() {
         return this.y;
     }

     /**
      * 获取图片速度
      *
      * @return int 图片速度
      */
     public int getSpeed() {
         return this.speed;
     }

     /**
      * 设置x坐标
      *
      * @param x
      *            int x坐标
      * @return void
      */
     public void setX(int x) {
         this.x = x;
     }

     /**
      * 设置y坐标
      *
      * @param y
      *            int y坐标
      * @return void
      */
     public void setY(int y) {
         this.y = y;
     }

     /**
      * 返回图片
      *
      * @return Image 图片
      */
     public Image getImage() {
         return this.image;
     }
 }

BallComponent

 package org.crazyit.ball;

 import javax.swing.JFrame;
 import javax.swing.JPanel;
 import javax.swing.Timer;
 import java.awt.Dimension;
 import java.awt.Image;
 import java.awt.Graphics;
 import java.awt.Color;
 import java.awt.event.KeyAdapter;
 import java.awt.event.KeyListener;
 import java.awt.event.KeyEvent;
 import java.awt.event.ActionListener;
 import java.awt.event.ActionEvent;
 import java.io.IOException;

 /**
  * 游戏界面
  *
  * @author yangenxiong [e-mail]
  * @author Kelvin Mak [e-mail]
  * @version  1.0
  * <br/>网站: <a href="http://www.crazyit.org">疯狂Java联盟</a>
  * <br>Copyright (C), 2009-2010, yangenxiong
  * <br>This program is protected by copyright laws.
  */
 public class BallFrame extends JFrame {
     // 定义JPanel的宽度
     private final int BALLPANEL_WIDTH = 307;
     // 定义JPanel的高度
     private final int BALLPANEL_HEIGHT = 400;
     // 定义画板
     private BallPanel ballPanel = null;
     // 定义档板
     // private Image stick = null;
     // 设置档板x坐标
     private int stickX = -1;
     // 创建一个BallService实例
     private BallService service = null;
     // 定义一个timer
     Timer timer = null;

     /**
      * 默认构造器
      */
     public BallFrame() throws IOException {
         super();
         // 初始化
         initialize();
     }

     /**
      * 初始化界面
      *
      * @return void
      */
     public void initialize() throws IOException {
         // 设置窗口的标题
         this.setTitle("弹球");
         // 设置为不可改变大小
         this.setResizable(false);
         // 设置背景为黑色
         this.setBackground(Color.BLACK);
         // 获取画板
         ballPanel = getBallPanel();
         // 创建BallService实例
         service = new BallService(this, BALLPANEL_WIDTH, BALLPANEL_HEIGHT);

         // 定义每0.1秒执行一次监听器
         ActionListener task = new ActionListener() {
             public void actionPerformed(ActionEvent e) {
                 // 开始改变位置
                 service.run();
                 // 刷新画板
                 ballPanel.repaint();
             }
         };
         // 如果timer不为空
         if (timer != null) {
             // 重新开始timer
             timer.restart();
         } else {
             // 新建一个timer
             timer = new Timer(100, task);
             // 开始timer
             timer.start();
         }

         this.add(ballPanel);
         // 增加事件监听器
         KeyListener[] klarr = this.getKeyListeners();
         if (klarr.length == 0) {
             // 定义键盘监听适配器
             KeyListener keyAdapter = new KeyAdapter() {
                 public void keyPressed(KeyEvent ke) {
                     // 改变档板的坐标
                     service.setStickPos(ke);
                 }
             };
             this.addKeyListener(keyAdapter);
         }
     }

     /**
      * 获取画板
      *
      * @return BallPanel 返回BallPanle
      */
     public BallPanel getBallPanel() {

         if (ballPanel == null) {
             // 新建一个画板
             ballPanel = new BallPanel();
             // 设置画板的大小
             ballPanel.setPreferredSize(new Dimension(BALLPANEL_WIDTH,
                     BALLPANEL_HEIGHT));
         }
         return ballPanel;
     }

     // 定义一个JPanel内部类来完成画图功能
     public class BallPanel extends JPanel {
         /**
          * 重写void paint( Graphics g )方法
          *
          * @param g
          *            Graphics
          * @return void
          */
         public void paint(Graphics g) {
             // 画图
             service.draw(g);
         }
     }

 }

BallFrame

 package org.crazyit.ball;

 import java.io.IOException;

 import javax.swing.JFrame;

 /**
  * 游戏入口类
  *
  * @author yangenxiong [e-mail]
  * @author Kelvin Mak [e-mail]
  * @version  1.0
  * <br/>网站: <a href="http://www.crazyit.org">疯狂Java联盟</a>
  * <br>Copyright (C), 2009-2010, yangenxiong
  * <br>This program is protected by copyright laws.
  */
 public class BallGame {
     /**
      * 开始游戏
      *
      * @return void
      */
     public static void main(String[] args) throws IOException {
         BallFrame ballFrame = new BallFrame();
         ballFrame.pack();
         ballFrame.setVisible(true);
         ballFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
     }
 }

BallGame

 package org.crazyit.ball;

 import java.awt.event.KeyEvent;
 import java.awt.Image;
 import java.awt.Graphics;
 import java.io.IOException;

 /**
  * 处理游戏逻辑的对象
  *
  * @author yangenxiong [e-mail]
  * @author Kelvin Mak [e-mail]
  * @version  1.0
  * <br/>网站: <a href="http://www.crazyit.org">疯狂Java联盟</a>
  * <br>Copyright (C), 2009-2010, yangenxiong
  * <br>This program is protected by copyright laws.
  */
 public class BallService {
     // 定义一个Stick(档板)
     private Stick stick = null;
     // 定义一个弹球
     private Ball ball = null;
     // 定义一个游戏结束图片
     private BallComponent gameOver = null;
     // 定义一个赢了游戏的图片
     private BallComponent won = null;
     // 定义一个砖块图片数组
     private Brick[][] bricks = null;
     private int width;
     private int height;
     BallFrame ballFrame = null;

     /**
      * 私有空构造器
      */
     private BallService() {
         super();
     }

     /**
      *
      * @param frame
      *            JFrame JFrame实例
      * @param width
      *            int 宽
      * @param height
      *            int 高
      * @return BallService
      */
     public BallService(BallFrame frame, int width, int height)
             throws IOException {
         // 初始化变量
         this.width = width;
         this.height = height;
         this.ballFrame = frame;
         // 创建一个Stick(档板)实例
         stick = new Stick(width, height, "img/stick.jpg");
         // 创建一个弹球的实例
         ball = new Ball(width, height, stick.getImage().getHeight(null),
                 "img/ball.gif");
         // 游戏结束图片
         gameOver = new BallComponent("img/over.gif");
         // 赢图片
         won = new BallComponent("img/win.gif");
         // 砖块图片数组
         bricks = createBrickArr("img/brick.gif", 11, 6);
     }

     /**
      * run
      *
      * @return void
      */
     public void run() {
         // 弹球坐标改变
         setBallPos();
         // 道具坐标改改变
         setMagicPos();
     }

     /**
      * 设置档板图片的位置
      *
      * @param ke
      *            KeyEvent 键盘事件
      * @return void
      */
     public void setStickPos(KeyEvent ke) {
         // 把弹球的运动状态设为true
         ball.setStarted(true);
         // 如果是左方向键
         if (ke.getKeyCode() == KeyEvent.VK_LEFT) {
             if (stick.getX() - stick.SPEED > 0) {
                 // x坐标向左移动
                 stick.setX(stick.getX() - stick.SPEED);
             }
         }
         // 如果是右方向键
         if (ke.getKeyCode() == KeyEvent.VK_RIGHT) {
             if (stick.getX() + stick.SPEED < width - stick.getPreWidth()) {
                 // x坐标向右移动
                 stick.setX(stick.getX() + stick.SPEED);
                 // ballFrame.getBallGame().reStart( ballFrame );
             }
         }
         // 如果是F2键
         if (ke.getKeyCode() == KeyEvent.VK_F2) {
             // 初始化ballFrame
             try {
                 ballFrame.initialize();
             } catch (IOException e) {
                 System.out.println(e.getMessage());
             }
         }
     }

     /**
      * 设置小球图片的位置
      *
      * @return void
      */
     public void setBallPos() {
         // 正数的数度
         int absSpeedX = Math.abs(ball.getSpeedX());
         int absSpeedY = Math.abs(ball.getSpeedY());
         // 如果游戏已经开始而且没有结束
         if (ball.isStarted()) {
             // 如果小球碰到左边界
             if (ball.getX() - absSpeedX < 0) {
                 // 重新设置x坐标
                 ball.setX(ball.getImage().getWidth(null));
                 // 把x方向的速度设为反方向
                 ball.setSpeedX(-ball.getSpeedX());
             }
             // 如果小球碰到右边界
             if (ball.getX() + absSpeedX > width
                     - ball.getImage().getWidth(null)) {
                 // 重新设置x坐标
                 ball.setX(width - ball.getImage().getWidth(null) * 2);
                 // 把x方向的速度设为反方向
                 ball.setSpeedX(-ball.getSpeedX());
             }
             // 如果小球碰到上边界
             if (ball.getY() - absSpeedY < 0) {
                 // 重新设置y坐标
                 ball.setY(ball.getImage().getWidth(null));
                 // 把y方向的速度设为反方向
                 ball.setSpeedY(-ball.getSpeedY());
             }
             // 如果小球碰到下边界
             if (ball.getY() + absSpeedY > height
                     - stick.getImage().getHeight(null)) {
                 // 如果小球与档板有碰撞
                 if (isHitStick(ball)) {
                     // 重新设置y坐标
                     ball.setY(height - ball.getImage().getHeight(null) * 2);
                     // 把y方向的速度设为反方向
                     ball.setSpeedY(-ball.getSpeedY());
                 }
             }
             // 与砖块碰撞后的运动
             for (int i = bricks.length - 1; i > -1; i--) {
                 for (int j = bricks[i].length - 1; j > -1; j--) {
                     // 如果小球与砖块有碰撞
                     if (isHitBrick(bricks[i][j])) {
                         if (ball.getSpeedY() > 0) {
                             ball.setSpeedY(-ball.getSpeedY());
                         }
                     }
                 }
             }
             // 结束游戏
             if (ball.getY() > height) {
                 ball.setStop(true);
             }

             // 设置x坐标
             ball.setX(ball.getX() - (int) (Math.random() * 2)
                     - ball.getSpeedX());
             // 设置y坐标
             ball.setY(ball.getY() - (int) (Math.random() * 2)
                     - ball.getSpeedY());
         }
     }

     /**
      * 小球与砖块是否有碰撞
      *
      * @return boolean
      */
     public boolean isHitBrick(Brick brick) {
         if (brick.isDisable()) {
             return false;
         }
         // ball的圆心x坐标
         double ballX = ball.getX() + ball.getImage().getWidth(null) / 2;
         // ball的圆心y坐标
         double ballY = ball.getY() + ball.getImage().getHeight(null) / 2;
         // brick的中心x坐标
         double brickX = brick.getX() + brick.getImage().getWidth(null) / 2;
         // brick的中心y坐标
         double brickY = brick.getY() + brick.getImage().getHeight(null) / 2;
         // 两个坐标点的距离
         double distance = Math.sqrt(Math.pow(ballX - brickX, 2)
                 + Math.pow(ballY - brickY, 2));
         // 如果两个图形重叠，返回true;
         if (distance < (ball.getImage().getWidth(null) + brick.getImage()
                 .getWidth(null)) / 2) {
             // 使brick无效
             brick.setDisable(true);
             return true;

         }
         return false;
     }

     /**
      * BallComponent是否与档板有碰撞
      *
      * @param image
      *            BallComponent 图像
      * @return boolean
      */
     public boolean isHitStick(BallComponent bc) {
         // 获取图片对象
         Image tempImage = bc.getImage();
         // 如果与档板有碰撞
         if (bc.getX() + tempImage.getWidth(null) > stick.getX()
                 && bc.getX() < stick.getX() + stick.getPreWidth()
                 && bc.getY() + tempImage.getHeight(null) > stick.getY()) {
             return true;
         }
         return false;
     }

     /**
      * 设置道具的位置
      *
      * @return void
      */
     public void setMagicPos() {
         for (int i = 0; i < bricks.length; i++) {
             for (int j = 0; j < bricks[i].length; j++) {
                 // 获取magic
                 Magic magic = bricks[i][j].getMagic();
                 if (magic != null) {
                     // 如果这个brick的状态是无效的
                     if (bricks[i][j].isDisable() && magic.getY() < height) {
                         // 设置magic的y坐标向下增加
                         magic.setY(magic.getY() + magic.getSpeed());
                         // 设置档板的宽度
                         setStickWidth(magic);

                     }
                 }
             }
         }
     }

     /**
      * 设置档板的长度
      *
      * @param magic
      *            Magic 道具
      * @return void
      */
     public void setStickWidth(Magic magic) {
         if (isHitStick(magic)) {
             // 道具的作用
             magic.magicDo(stick);
         }
     }

     /**
      * 判断是否赢了
      *
      * @return boolean
      */
     public boolean isWon() {
         // 如果消了全部砖块，则为赢
         for (int i = 0; i < bricks.length; i++) {
             for (int j = 0; j < bricks[i].length; j++) {
                 if (!bricks[i][j].isDisable()) {
                     return false;
                 }
             }
         }
         return true;
     }

     /**
      * 创建一个类型为Brick的数组
      *
      * @param path
      *            String 图像路径
      * @param xSize
      *            int
      * @param ySize
      *            int
      * @return Brick[][]
      */
     public Brick[][] createBrickArr(String path, int xSize, int ySize)
             throws IOException {
         // 创建一个Brick[][]
         Brick[][] bricks = new Brick[xSize][ySize];
         int x = 0;
         int y = 0;
         int random = 0;
         int imageSize = 28;
         boolean isDisable = false;
         // 迭代初始化数组
         for (int i = 0; i < xSize; i++) {
             for (int j = 0; j < ySize; j++) {
                 // 创建一个新的砖块
                 random = (int) (Math.random() * 3);
                 x = i * imageSize;
                 y = j * imageSize;
                 // 一定机率没有砖块
                 isDisable = Math.random() > 0.8 ? true : false;
                 if (isDisable) {
                     random = 0;
                 }
                 Brick brick = new Brick(path, random, x, y);
                 brick.setDisable(isDisable);
                 // 设置x坐标
                 brick.setX(x);
                 // 设置y坐标
                 brick.setY(y);
                 bricks[i][j] = brick;
             }
         }
         return bricks;
     }

     /**
      * 画图
      *
      * @param g
      *            Graphics 用来画图的对象
      * @return void
      */
     public void draw(Graphics g) {
         // 如果赢了
         if (isWon()) {
             // 绘制赢的图片
             g.drawImage(won.getImage(), won.getX(), won.getY(), width,
                     height - 10, null);
         } else if (ball.isStop()) {
             // 绘制游戏结束图像
             g.drawImage(gameOver.getImage(), gameOver.getX(), gameOver.getY(),
                     width, height - 10, null);
         } else {
             // 清除原来的图像
             g.clearRect(0, 0, width, height);
             // 绘制档板图像
             g.drawImage(stick.getImage(), stick.getX(), stick.getY(), stick
                     .getPreWidth(), stick.getImage().getHeight(null), null);
             // 绘制弹球图像
             g.drawImage(ball.getImage(), ball.getX(), ball.getY(), null);
             // 迭代绘制砖块图像
             for (int i = 0; i < bricks.length; i++) {
                 for (int j = 0; j < bricks[i].length; j++) {
                     BallComponent magic = bricks[i][j].getMagic();
                     // 如果这个砖块图像对像是有效的
                     if (!bricks[i][j].isDisable()) {
                         // 里面的数字1为砖块图像间的间隙
                         g.drawImage(bricks[i][j].getImage(), bricks[i][j]
                                 .getX(), bricks[i][j].getY(), bricks[i][j]
                                 .getImage().getWidth(null) - 1, bricks[i][j]
                                 .getImage().getHeight(null) - 1, null);
                     } else if (magic != null && magic.getY() < height) {
                         g.drawImage(magic.getImage(), magic.getX(), magic
                                 .getY(), null);
                     }
                 }
             }
         }
     }
 }

BallService

 package org.crazyit.ball;

 import java.awt.Image;
 import java.io.IOException;

 /**
  * 砖块类
  *
  * @author yangenxiong [e-mail]
  * @author Kelvin Mak [e-mail]
  * @version  1.0
  * <br/>网站: <a href="http://www.crazyit.org">疯狂Java联盟</a>
  * <br>Copyright (C), 2009-2010, yangenxiong
  * <br>This program is protected by copyright laws.
  */
 public class Brick extends BallComponent {

     // 定义道具
     private Magic magic = null;
     // 定义一个boolean变量设置本类是否有效
     private boolean disable = false;
     public static final int MAGIC_LONG_TYPE = 1;
     public static final int MAGIC_SHORT_TYPE = 2;

     /**
      * 构造器
      *
      * @return void
      */
     public Brick(String path, int type, int x, int y) throws IOException {
         super(path);
         if (type == Brick.MAGIC_LONG_TYPE) {
             this.magic = new LongMagic("img/long.gif", x, y);
         } else if (type == Brick.MAGIC_SHORT_TYPE) {
             this.magic = new ShortMagic("img/short.gif", x, y);
         }
         if (this.magic != null) {
             this.magic.setX(x);
             this.magic.setY(y);
         }
     }

     /**
      * 设置本类有没有效
      *
      * @param disable
      *            boolean
      * @return void
      */
     public void setDisable(boolean disable) {
         this.disable = disable;
     }

     /**
      * 查看本类有没有效
      *
      * @return boolean 是否有效
      */
     public boolean isDisable() {
         return this.disable;
     }

     /**
      * 获取道具
      *
      * @return String magic
      */
     public Magic getMagic() {
         return this.magic;
     }

     /**
      * 设置道具
      *
      * @return String magic
      */
     public void setMagic(Magic magic) {
         this.magic = magic;
     }
 }

Brick

 package org.crazyit.ball;

 import java.io.IOException;

 /**
  * 道具对象
  *
  * @author yangenxiong [e-mail]
  * @author Kelvin Mak [e-mail]
  * @version  1.0
  * <br/>网站: <a href="http://www.crazyit.org">疯狂Java联盟</a>
  * <br>Copyright (C), 2009-2010, yangenxiong
  * <br>This program is protected by copyright laws.
  */
 public abstract class Magic extends BallComponent {
     /**
      * 提供给子类调用的构造器
      *
      * @param path
      *            String 文件路径
      * @param x
      *            int x坐标
      * @param y
      *            int y坐标
      */
     public Magic(String path, int x, int y) throws IOException {
         super(path, x, y);
     }

     /**
      * 道具的功能
      *
      * @param stitck
      *            Stick
      * @return void
      */
     public abstract void magicDo(Stick stick);
 }

Magic

 package org.crazyit.ball;

 import java.io.IOException;

 /**
  * 使挡板变长的道具
  *
  * @author yangenxiong [e-mail]
  * @author Kelvin Mak [e-mail]
  * @version  1.0
  * <br/>网站: <a href="http://www.crazyit.org">疯狂Java联盟</a>
  * <br>Copyright (C), 2009-2010, yangenxiong
  * <br>This program is protected by copyright laws.
  */
 public class LongMagic extends Magic {
     /**
      * 构造器
      *
      * @param path
      *            String 文件路径
      * @param x
      *            int x坐标
      * @param y
      *            int y坐标
      */
     public LongMagic(String path, int x, int y) throws IOException {
         super(path, x, y);
     }

     /**
      * 道具的功能 : 档板变长
      *
      * @param stitck
      *            Stick
      * @return void
      */
     public void magicDo(Stick stick) {
         double imageWidth = stick.getImage().getWidth(null);
         // 如果档板没有变长过
         if (stick.getPreWidth() <= imageWidth) {
             // 将档板的长度改为双倍
             stick.setPreWidth((int) (stick.getPreWidth() * 2));
         }
     }
 }

LongMagic

 package org.crazyit.ball;

 import java.io.IOException;

 /**
  * 使挡板变短的道具
  *
  * @author yangenxiong [e-mail]
  * @author Kelvin Mak [e-mail]
  * @version  1.0
  * <br/>网站: <a href="http://www.crazyit.org">疯狂Java联盟</a>
  * <br>Copyright (C), 2009-2010, yangenxiong
  * <br>This program is protected by copyright laws.
  */
 public class ShortMagic extends Magic {
     /**
      * 构造器
      *
      * @param path
      *            String 文件路径
      * @param x
      *            int x坐标
      * @param y
      *            int y坐标
      */
     public ShortMagic(String path, int x, int y) throws IOException {
         super(path, x, y);
     }

     /**
      * 道具的功能 : 档板变短
      *
      * @param stitck
      *            Stick
      * @return void
      */
     public void magicDo(Stick stick) {
         double imageWidth = stick.getImage().getWidth(null);
         // 如果档板没有变短过
         if (stick.getPreWidth() >= imageWidth) {
             // 将档板的宽度改为一半
             stick.setPreWidth((int) (stick.getPreWidth() * 0.5));
         }
     }
 }

ShortMagic

 package org.crazyit.ball;

 import java.io.IOException;

 /**
  * 挡板类
  *
  * @author yangenxiong [e-mail]
  * @author Kelvin Mak [e-mail]
  * @version  1.0
  * <br/>网站: <a href="http://www.crazyit.org">疯狂Java联盟</a>
  * <br>Copyright (C), 2009-2010, yangenxiong
  * <br>This program is protected by copyright laws.
  */
 public class Stick extends BallComponent {
     // 定义档板移动的速度
     public static final int SPEED = 20;
     // 定义档板初始的长度
     private int preWidth = 0;

     /**
      * 有参数构造器
      *
      * @param panelWidth
      *            int 画板宽度
      * @param panelHeight
      *            int 画板高度
      * @param path
      *            String 图片路径
      */
     public Stick(int panelWidth, int panelHeight, String path)
             throws IOException {
         // 调用父构造器
         super(panelWidth, panelHeight, path);
         // 设置y坐标
         this.setY(panelHeight - super.getImage().getHeight(null));
         // 设置原本的长度
         this.preWidth = super.getImage().getWidth(null);
     }

     /**
      * 获取初始长度
      *
      * @return int 初始长度
      */
     public int getPreWidth() {
         return this.preWidth;
     }

     /**
      * 设置初始长度
      *
      * @return void
      */
     public void setPreWidth(int preWidth) {
         this.preWidth = preWidth;
     }

 }

Stick