弹弹球

package cn.hncu.p24;import java.awt.BorderLayout;import java.awt.Canvas;import java.awt.Color;import java.awt.Dimension;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.JButton;import javax.swing.JColorChooser;import javax.swing.JFrame;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,ActionListener {BallsCanvas ballscanvas;JSpinner spinner;JButton btn;Color color;public BallsJFrame() {super("弹弹球");Dimension dms = getToolkit().getScreenSize();setBounds(dms.width / 4, dms.height / 4, dms.width / 2, dms.height / 2);setDefaultCloseOperation(EXIT_ON_CLOSE);Color[] colors = { Color.red, Color.green, Color.cyan, Color.blue,Color.black };ballscanvas = new BallsCanvas(colors, 100);getContentPane().add(ballscanvas);northLayout();setVisible(true);}private void northLayout() {JPanel p2 = new JPanel();getContentPane().add(p2, BorderLayout.SOUTH);spinner = new JSpinner();spinner.setValue(100);spinner.addChangeListener(this);btn = new JButton("添加彩球");btn.addActionListener(this);p2.add(btn);p2.add(spinner);}public static void main(String[] args) {new BallsJFrame();}@Overridepublic void stateChanged(ChangeEvent e) {int delay = (Integer) spinner.getValue();ballscanvas.timer.setDelay(delay);}@Overridepublic void actionPerformed(ActionEvent e) {color = JColorChooser.showDialog(this, "颜色选择", Color.red);ballscanvas.pulsBall(new Ball(color, ballscanvas));}}class BallsCanvas extends Canvas implements FocusListener, ActionListener {Ball[] balls;Timer timer;int delay;int width;int hight;public BallsCanvas(Color[] colors, int delay) {balls = new Ball[colors.length];this.setSize(200, 300);getDimension();// 得到宽和高for (int i = 0; i < colors.length; i++) {balls[i] = new Ball(colors[i], this);}// 使用定时器timer = new Timer(delay, this);// 注册actionListemer监听器**********************timer.start();this.addFocusListener(this);}public void pulsBall(Ball ball) {Ball[] temp = new Ball[balls.length + 1];for (int i = 0; i < balls.length; i++) {temp[i] = balls[i];}temp[balls.length] = ball;balls = temp;repaint();}public void getDimension() {width = this.getWidth();hight = this.getHeight();}@Overridepublic void paint(Graphics g) {for (int i = 0; i < balls.length; i++) {g.setColor(balls[i].color);balls[i].x = balls[i].left ? balls[i].x - 5 : balls[i].x + 5;if (balls[i].x <= 0 || balls[i].x >= this.getWidth()) {balls[i].left = !balls[i].left;}balls[i].y = balls[i].up ? balls[i].y - 5 : balls[i].y + 5;if (balls[i].y <= 0 || balls[i].y >= this.getHeight()) {balls[i].up = !balls[i].up;}g.fillOval(balls[i].x, balls[i].y, balls[i].r, balls[i].r);for (int j = 0; j < balls.length; j++) {if (i != j) {if ((Math.sqrt((balls[i].x - balls[j].x)* (balls[i].x - balls[j].x)+ (balls[i].y - balls[j].y)* (balls[i].y - balls[j].y))) <= balls[i].r) {balls[i].left = !balls[i].left;balls[i].up = !balls[i].up;balls[j].left = !balls[j].left;balls[j].up = !balls[j].up;}}}}}@Overridepublic void focusGained(FocusEvent e) {timer.stop();}@Overridepublic void focusLost(FocusEvent e) {timer.restart();}@Overridepublic void actionPerformed(ActionEvent e) {repaint();}}class Ball {int x = 1, y = 1, r = 20;boolean up, left;Color color;public Ball(Color color, BallsCanvas ballscanvas) {int row = (int) (Math.random() * 200) % (ballscanvas.width);int column = (int) (Math.random() * 300) % (ballscanvas.hight);this.x = x * row;this.y = y * column;up = left = false;this.color = color;}}