Java一个简单的反弹动画练习

说明

做了一个小球和星型做反弹动画的窗体作为练习，分享给大家，为了方便和我一样的小白可以看的比较明白，所以尽量详细的标注了注释，希望能帮到同样在学习路上的朋友

代码详解

创建窗体代码

public class AnimationJFrame extends JFrame {//实例化属性private final DrawCircleAndStar drawCircleAndStar = new DrawCircleAndStar();//实例化图形绘制private final JButton jButton = new JButton();//实例化按钮private final AnimationRun animationRun = new AnimationRun();//实例化线程//设置绘图全局属性private int circleX = 0;//圆形的初始位置X坐标private int circleY = 10;//圆形的初始位置Y坐标private int circleXDirection = 1;//圆形运动X轴方向private int circleYDirection = 1;//圆形运动Y轴方向private int starX = 355;//星型的初始位置X坐标private int starY = 200;//星型的初始位置Y坐标private int starXDirection = 1;//星形运动X轴方向private int starYDirection = 1;//星形运动Y轴方向//构造方法构造窗体public AnimationJFrame(){//窗体基本设置Container conn = getContentPane();//建立窗体容器setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);//设置窗体关闭方式setBounds(300,300,400,400);//设置窗体位置及大小setResizable(false);//窗体大小不可改变setLayout(null);//清空窗体布局管理器，不采用默认布局//创建动画布局JPanel jPanel = new JPanel();//实例化布局jPanel.setLayout(null);//清空布局的布局管理器，不采用默认布局jPanel.setBounds(10, 10, 365, 300);//动画布局的位置及大小jPanel.setBorder(BorderFactory.createLineBorder(Color.BLACK));//设置动画布局的边框jPanel.setBackground(Color.LIGHT_GRAY);//设置动画布局的底色//创建动画图形的标签容器JLabel jLabel = new JLabel();//实例化标签jLabel.setBounds(0,0,365,300);//设置动画标签的大小和位置//设置绘图标签drawCircleAndStar.setBackground(new Color(0,0,0,0));//设置绘图标签的背景透明drawCircleAndStar.setSize(365,300);//设置绘图标签的大小jLabel.add(drawCircleAndStar);//添加绘图板到标签jPanel.add(jLabel);//添加动画标签到动画布局//设置按键jButton.setText("开始");//设置按键显示文字jButton.setFont(new Font("黑体", Font.PLAIN, 14));//设置按键文字的字体jButton.setBounds(275, 320, 100, 22);//设置按键的位置和大小//添加原件到窗体容器conn.add(jPanel);//添加动漫布局到容器conn.add(jButton);//添加按钮到容器//给按钮添加监听jButton.addActionListener(e -> {if (e.getActionCommand().equals("开始")){jButton.setText("暂停一下");//更改按键文字animationRun.start();//启动线程}else if (e.getActionCommand().equals("暂停一下")){jButton.setText("继续");animationRun.pause();//暂停线程}else if (e.getActionCommand().equals("继续")){jButton.setText("暂停一下");animationRun.restart();//重启线程}});}

这里需要说明的是，代码中直接把窗体创建在构造方法中，但是直接在构造方法中设置窗体只适用于线程较简单的程序，如果在正式的项目中，应该避免这种写法，因为swing是线程不安全的，应该对窗体单独建立窗体方法容器，例如：

 public AnimationJFrame() {SwingUtilities.invokeLater(() -> {initUI();});}private void initUI() {//代码块...........}

创建绘图板

    //创建绘图板class DrawCircleAndStar extends JLabel{@Overridepublic void paintComponent(Graphics g){//重写paintComponentsuper.paintComponent(g);//继承父类的构造方法Graphics2D graphics2D = (Graphics2D) g;graphics2D.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);//设置绘图抗锯齿//绘制圆形graphics2D.setColor(Color.RED);//设置填充颜色，红色graphics2D.fillOval(circleX,circleY,15,15);//设置圆形的位置和大小//绘制星型graphics2D.setColor(Color.BLUE);//设置填充色，蓝色//设置星型的属性int radius = 10;//设置星型的大小int[] xPoints = new int[10];//星型顶点的X坐标int[] yPoints = new int[10];//星型顶点的Y坐标//计算星型顶点的坐标及初始角度for (int i = 0; i < 10; i++) {double baseAngle = i * 2 * Math.PI / 10 + Math.PI / 2;//初始角度if (i % 2 == 0) {//外围顶点的坐标xPoints[i] = starX + (int) (radius * Math.cos(baseAngle));yPoints[i] = starY - (int) (radius * Math.sin(baseAngle));} else {//内部顶点的坐标xPoints[i] = starX + (int) (radius * Math.cos(baseAngle) * 0.5);yPoints[i] = starY - (int) (radius * Math.sin(baseAngle) * 0.5);}}Polygon star = new Polygon(xPoints, yPoints, 10);//绘制星型graphics2D.fillPolygon(star);//填充星型}}

创建绘图板，别的没有什么可说的，这里切记一点，无论绘图板继承自布局还是标签，相对的布局和标签是没有大小的，必须在窗体设置中，为它们设定尺寸，比如本代码中的

        drawCircleAndStar.setBackground(new Color(0,0,0,0));//设置绘图标签的背景透明drawCircleAndStar.setSize(365,300);//设置绘图标签的大小

如果不设置大小，将无法将绘图板图形显示到容器

创建线程

    //创建运行线程class AnimationRun extends Thread{boolean flag = false;//设置挂起标志synchronized void pause(){//暂停方法flag = true;}synchronized void restart(){//重启方法notifyAll();flag = false;}//重写run@Overridepublic void run(){//动画运行while (true) {//挂起区synchronized (this){while (flag){try {wait();//等待挂起} catch (InterruptedException e) {throw new RuntimeException(e);}}}//判断圆形运动方向if (circleX == 0) {circleXDirection = 1;} else if (circleX == 350) {circleXDirection = -1;}if (circleY == 0) {circleYDirection = 1;} else if (circleY == 285) {circleYDirection = -1;}//判断星型运动方向if (starX == 10){starXDirection = 1;}else if (starX == 355){starXDirection = -1;}if (starY == 10){starYDirection = 1;}else if (starY == 290){starYDirection = -1;}//设置绘图延迟try {Thread.sleep(10);} catch (InterruptedException e) {throw new RuntimeException(e);}//计算新的圆形位置和星型的位置circleX += circleXDirection;circleY += circleYDirection;starX += starXDirection;starY += starYDirection;//重绘绘图板drawCircleAndStar.repaint();}}}

synchronized相对来说并不是最优的选择，消耗较高，建议优化，另外一个这里重写的不是paint而是重写的paintComponent因为重写paintComponent只绘制图形主体，不会影响边框和背景，建议单独绘制元素的时候使用paintComponent而不是paint。

运行结果

完整代码

import javax.swing.*;
import java.awt.*;public class AnimationJFrame extends JFrame {//实例化属性private final DrawCircleAndStar drawCircleAndStar = new DrawCircleAndStar();//实例化图形绘制private final JButton jButton = new JButton();//实例化按钮private final AnimationRun animationRun = new AnimationRun();//实例化线程//设置绘图全局属性private int circleX = 0;//圆形的初始位置X坐标private int circleY = 10;//圆形的初始位置Y坐标private int circleXDirection = 1;//圆形运动X轴方向private int circleYDirection = 1;//圆形运动Y轴方向private int starX = 355;//星型的初始位置X坐标private int starY = 200;//星型的初始位置Y坐标private int starXDirection = 1;//星形运动X轴方向private int starYDirection = 1;//星形运动Y轴方向//构造方法构造窗体public AnimationJFrame(){//窗体基本设置Container conn = getContentPane();//建立窗体容器setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);//设置窗体关闭方式setBounds(300,300,400,400);//设置窗体位置及大小setResizable(false);//窗体大小不可改变setLayout(null);//清空窗体布局管理器，不采用默认布局//创建动画布局JPanel jPanel = new JPanel();//实例化布局jPanel.setLayout(null);//清空布局的布局管理器，不采用默认布局jPanel.setBounds(10, 10, 365, 300);//动画布局的位置及大小jPanel.setBorder(BorderFactory.createLineBorder(Color.BLACK));//设置动画布局的边框jPanel.setBackground(Color.LIGHT_GRAY);//设置动画布局的底色//创建动画图形的标签容器JLabel jLabel = new JLabel();//实例化标签jLabel.setBounds(0,0,365,300);//设置动画标签的大小和位置//设置绘图标签drawCircleAndStar.setBackground(new Color(0,0,0,0));//设置绘图标签的背景透明drawCircleAndStar.setSize(365,300);//设置绘图标签的大小jLabel.add(drawCircleAndStar);//添加绘图板到标签jPanel.add(jLabel);//添加动画标签到动画布局//设置按键jButton.setText("开始");//设置按键显示文字jButton.setFont(new Font("黑体", Font.PLAIN, 14));//设置按键文字的字体jButton.setBounds(275, 320, 100, 22);//设置按键的位置和大小//添加原件到窗体容器conn.add(jPanel);//添加动漫布局到容器conn.add(jButton);//添加按钮到容器//给按钮添加监听jButton.addActionListener(e -> {if (e.getActionCommand().equals("开始")){jButton.setText("暂停一下");//更改按键文字animationRun.start();//启动线程}else if (e.getActionCommand().equals("暂停一下")){jButton.setText("继续");animationRun.pause();//暂停线程}else if (e.getActionCommand().equals("继续")){jButton.setText("暂停一下");animationRun.restart();//重启线程}});}//创建绘图板class DrawCircleAndStar extends JLabel{@Overridepublic void paintComponent(Graphics g){//重写paintComponentsuper.paintComponent(g);//继承父类的构造方法Graphics2D graphics2D = (Graphics2D) g;graphics2D.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);//设置绘图抗锯齿//绘制圆形graphics2D.setColor(Color.RED);//设置填充颜色，红色graphics2D.fillOval(circleX,circleY,15,15);//设置圆形的位置和大小//绘制星型graphics2D.setColor(Color.BLUE);//设置填充色，蓝色//设置星型的属性int radius = 10;//设置星型的大小int[] xPoints = new int[10];//星型顶点的X坐标int[] yPoints = new int[10];//星型顶点的Y坐标//计算星型顶点的坐标及初始角度for (int i = 0; i < 10; i++) {double baseAngle = i * 2 * Math.PI / 10 + Math.PI / 2;//初始角度if (i % 2 == 0) {//外围顶点的坐标xPoints[i] = starX + (int) (radius * Math.cos(baseAngle));yPoints[i] = starY - (int) (radius * Math.sin(baseAngle));} else {//内部顶点的坐标xPoints[i] = starX + (int) (radius * Math.cos(baseAngle) * 0.5);yPoints[i] = starY - (int) (radius * Math.sin(baseAngle) * 0.5);}}Polygon star = new Polygon(xPoints, yPoints, 10);//绘制星型graphics2D.fillPolygon(star);//填充星型}}//创建运行线程class AnimationRun extends Thread{boolean flag = false;//设置挂起标志synchronized void pause(){//暂停方法flag = true;}synchronized void restart(){//重启方法notifyAll();flag = false;}//重写run@Overridepublic void run(){//动画运行while (true) {//挂起区synchronized (this){while (flag){try {wait();//等待挂起} catch (InterruptedException e) {throw new RuntimeException(e);}}}//判断圆形运动方向if (circleX == 0) {circleXDirection = 1;} else if (circleX == 350) {circleXDirection = -1;}if (circleY == 0) {circleYDirection = 1;} else if (circleY == 285) {circleYDirection = -1;}//判断星型运动方向if (starX == 10){starXDirection = 1;}else if (starX == 355){starXDirection = -1;}if (starY == 10){starYDirection = 1;}else if (starY == 290){starYDirection = -1;}//设置绘图延迟try {Thread.sleep(10);} catch (InterruptedException e) {throw new RuntimeException(e);}//计算新的圆形位置和星型的位置circleX += circleXDirection;circleY += circleYDirection;starX += starXDirection;starY += starYDirection;//重绘绘图板drawCircleAndStar.repaint();}}}public static void main(String[] args) {new AnimationJFrame().setVisible(true);//启动程序}
}