JAVA核心技术之球体碰撞多线程版

  1 /**
  2    @version 1.32 2004-07-27
  3    @author Cay Horstmann
  4 */
  5 
  6 import java.awt.*;
  7 import java.awt.event.*;
  8 import java.awt.geom.*;
  9 import java.util.*;
 10 import javax.swing.*;
 11 
 12 /**
 13    Shows an animated bouncing ball.
 14 */
 15 public class BounceThread
 16 {
 17    public static void main(String[] args)
 18    {
 19       JFrame frame = new BounceFrame();
 20       frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
 21       frame.setVisible(true);
 22    }
 23 }
 24 
 25 /**
 26    A runnable that animates a bouncing ball.
 27 */
 28 class BallRunnable implements Runnable
 29 {
 30    /**
 31       Constructs the runnable.
 32       @aBall the ball to bounce
 33       @aPanel the component in which the ball bounces
 34    */
 35    public BallRunnable(Ball aBall, Component aComponent) 
 36    { 
 37       ball = aBall; 
 38       component = aComponent;
 39    }
 40 
 41    public void run()
 42    {
 43       try
 44       {
 45          for (int i = 1; i <= STEPS; i++)
 46          {
 47             ball.move(component.getBounds());
 48             component.repaint();
 49             Thread.sleep(DELAY);
 50          }
 51       }
 52       catch (InterruptedException e)
 53       {                    
 54       }
 55    }
 56 
 57    private Ball ball;
 58    private Component component;
 59    public static final int STEPS = 1000;
 60    public static final int DELAY = 5;
 61 }
 62 
 63 /**
 64    A ball that moves and bounces off the edges of a 
 65    rectangle
 66 */
 67 class Ball
 68 {
 69    /**
 70       Moves the ball to the next position, reversing direction
 71       if it hits one of the edges
 72    */
 73    public void move(Rectangle2D bounds)
 74    {
 75       x += dx;
 76       y += dy;
 77       if (x < bounds.getMinX())
 78       { 
 79          x = bounds.getMinX();
 80          dx = -dx;
 81       }
 82       if (x + XSIZE >= bounds.getMaxX())
 83       {
 84          x = bounds.getMaxX() - XSIZE; 
 85          dx = -dx; 
 86       }
 87       if (y < bounds.getMinY())
 88       {
 89          y = bounds.getMinY(); 
 90          dy = -dy;
 91       }
 92       if (y + YSIZE >= bounds.getMaxY())
 93       {
 94          y = bounds.getMaxY() - YSIZE;
 95          dy = -dy; 
 96       }
 97    }
 98 
 99    /**
100       Gets the shape of the ball at its current position.
101    */
102    public Ellipse2D getShape()
103    {
104       return new Ellipse2D.Double(x, y, XSIZE, YSIZE);
105    }
106 
107    private static final int XSIZE = 15;
108    private static final int YSIZE = 15;
109    private double x = 0;
110    private double y = 0;
111    private double dx = 1;
112    private double dy = 1;
113 }
114 
115 /**
116    The panel that draws the balls.
117 */
118 class BallPanel extends JPanel
119 {
120    /**
121       Add a ball to the panel.
122       @param b the ball to add
123    */
124    public void add(Ball b)
125    {
126       balls.add(b);
127    }
128 
129    public void paintComponent(Graphics g)
130    {
131       super.paintComponent(g);
132       Graphics2D g2 = (Graphics2D) g;
133       for (Ball b : balls)
134       {
135          g2.fill(b.getShape());
136       }
137    }
138 
139    private ArrayList<Ball> balls = new ArrayList<Ball>();
140 }
141 
142 /**
143    The frame with panel and buttons.
144 */
145 class BounceFrame extends JFrame
146 {
147    /**
148       Constructs the frame with the panel for showing the
149       bouncing ball and Start and Close buttons
150    */
151    public BounceFrame()
152    {
153       setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);
154       setTitle("BounceThread");
155 
156       panel = new BallPanel();
157       add(panel, BorderLayout.CENTER);
158       JPanel buttonPanel = new JPanel();
159       addButton(buttonPanel, "Start",
160          new ActionListener()
161          {  
162             public void actionPerformed(ActionEvent event)
163             {
164                addBall();
165             }
166          });
167       
168       addButton(buttonPanel, "Close",
169          new ActionListener()
170          {
171             public void actionPerformed(ActionEvent event)
172             {
173                System.exit(0);
174             }
175          });
176       add(buttonPanel, BorderLayout.SOUTH);
177    }
178 
179    /**
180       Adds a button to a container.
181       @param c the container
182       @param title the button title
183       @param listener the action listener for the button
184    */
185    public void addButton(Container c, String title, ActionListener listener)
186    {
187       JButton button = new JButton(title);
188       c.add(button);
189       button.addActionListener(listener);
190    }
191 
192    /**
193       Adds a bouncing ball to the canvas and starts a thread
194       to make it bounce
195    */
196    public void addBall()
197    {
198       Ball b = new Ball();
199       panel.add(b);
200       Runnable r = new BallRunnable(b, panel);
201       Thread t = new Thread(r);
202       t.start();
203    }
204 
205    private BallPanel panel;
206    public static final int DEFAULT_WIDTH = 450;
207    public static final int DEFAULT_HEIGHT = 350;  
208    public static final int STEPS = 1000;
209    public static final int DELAY = 3;
210 }