下面的3个类都在包cn.bjsxt.util中

1，Constant.java 中程序如下：

package cn.bjsxt.util;

public class Constant {

public static final int GAME_WIDTH = 800;

public static final int GAME_HEIGHT = 600;

}

2，GameUtil.java 中程序如下：

package cn.bjsxt.util;

import java.awt.Image;

import java.io.IOException;

import java.net.URL;

import java.awt.image.BufferedImage;

import javax.imageio.ImageIO;

public class GameUtil {

private GameUtil(){} //工具类将构造函数私有

public static Image GetImage(String

path){

URL u =

GameUtil.class.getClassLoader().getResource(path);

BufferedImage img = null;

try{

img =

ImageIO.read(u);

}catch (IOException e){

e.printStackTrace();

}

return img;

}

}

3，MyFrame.java中程序如下：

package cn.bjsxt.util;

import java.awt.Frame;

import java.awt.Image;

import java.awt.event.WindowAdapter;

import java.awt.event.WindowEvent;

//import cn.bjsxt.test.GameFrame.PaintThread;

public class MyFrame extends Frame{

public void launchFrame(){

setSize(Constant.GAME_WIDTH,

Constant.GAME_HEIGHT);

setLocation(100, 100);

setVisible(true);

addWindowListener(new

WindowAdapter(){

@Override

public void

windowClosed(WindowEvent e) {

System.exit(0);

} });

new

PaintThread().start();//启动重画线程

}

class PaintThread extends

Thread{

public void

run(){

while(true){

repaint();

try{

Thread.sleep(200);

}

catch (InterruptedException e){

e.printStackTrace();

}

}

}

}

}

下面的类都在包cn.bjsxt.solar中

4，Planet.java 中程序如下：

package cn.bjsxt.solar;

import java.awt.Color;

import java.awt.Graphics;

import java.awt.Image;

import cn.bjsxt.util.GameUtil;

public class Planet extends Star {

//除了star中拥有的图片，坐标外，行星沿着椭圆运行：长轴，短轴，速度，角度绕着一个star飞

double longAxis;//长轴

double shortAxis;//短轴

double speed;//速度

double degree;

Star center;

boolean satellite;

public void draw(Graphics g){

//g.drawImage(img, (int)x,

(int)y, null);

super.draw(g);

if (!satellite){

drawTrace(g);

}

move(); }

public void drawTrace(Graphics g){

double ovalX, ovalY, ovalWidth,

ovalHeight;

ovalWidth = longAxis*2;

ovalHeight = shortAxis*2;

ovalX = (center.x +

center.width/2 ) - longAxis;

ovalY = (center.y +

center.height/2) - shortAxis;

Color c = g.getColor();

g.setColor(Color.blue);

g.drawOval((int)ovalX,

(int)ovalY, (int)ovalWidth, (int)ovalHeight);

g.setColor(c);

}

//

center.width/2 center.height/2

public void move(){

//沿着椭圆轨迹飞行

x = (center.x + center.width/2)

+ longAxis*Math.cos(degree);

y = (center.y +

center.height/2) +

shortAxis*Math.sin(degree); degree += speed;

}

public Planet(String imgpath, double

longAxis,

double

shortAxis, double speed, Star center) {

super(GameUtil.GetImage(imgpath));

this.x = center.x +

longAxis;

this.y = center.y;

//this.img =

GameUtil.GetImage(imgpath);

this.longAxis = longAxis;

this.shortAxis =

shortAxis;

this.speed = speed;

this.center = center;

}

//？？？？？理论上来说，应该先有构造基类构造函数的情况，但是上面基类的x，

y，都没有构造？？？/??//star中有个默认构造函数，理解成直接调用不用参数的默认构造函数了？？？？其实super还是调用了

public Planet(String imgpath, double

longAxis,

double

shortAxis, double speed, Star center, boolean satellite) {

this(imgpath, longAxis,

shortAxis, speed, center);

this.satellite =

satellite;

}

//??????/、/?//下面两个函数没有调用？？？？？？/?//下面测试当我注释掉时整个程序是可以运行的

public Planet(Image img, double x, double

y){

super(img, x, y);

}

public Planet(String imgpath, double x, double

y){

super(imgpath, x, y);

}

}

5， star.java 中程序如下：

package cn.bjsxt.solar;

import java.awt.Graphics;

import java.awt.Image;

import cn.bjsxt.util.GameUtil;

public class Star {

Image img;

double x, y;

int width, height;

public void draw(Graphics g){

g.drawImage(img, (int)x,

(int)y, null);

}

public Star(){}

public Star(Image img){

this.img = img;

this.width =

img.getWidth(null);

this.height =

img.getHeight(null);

}

public Star(Image img, double x, double y){

//this.img = img;

this(img);

this.x = x;

this.y = y;

//this.width =

img.getWidth(null);

//this.height =

img.getHeight(null);

}

public Star(String imgpath, double x, double

y){

this(GameUtil.GetImage(imgpath),

x, y);

}

}

6， solarFrame.java 中程序如下

package cn.bjsxt.solar;

import java.awt.Graphics;

import java.awt.Image;

import cn.bjsxt.util.Constant;

//import cn.bjsxt.test.MyFrame.PaintThread;

import cn.bjsxt.util.GameUtil;

import cn.bjsxt.util.MyFrame;

public class solarFrame extends MyFrame {

Image bg =

GameUtil.GetImage("images/bg4.jpg");

//????有一个疑问，此处Image类怎么可以自动调用？？？，难道是下面主函数中创建new出solarFrame对象时会自动调用？？？一般是从主函数开始啊，主函数调用继承自MyFrame的launchFrame()

//该方法中规定了加载窗口的一些内容，包括起始位置，长宽等参数，同时该方法类中调用了 new PaintThread().start();//启动重画线程

//然后在同一个类中调用 class PaintThread extends

Thread，其中有repaint()函数调用，即会自动调用太阳主窗口中下面的paint方法,并在while循环中线程会每隔一段时间调用一次，实现动态效果

Star sun = new Star("images/sun5.jpg",

Constant.GAME_HEIGHT/1.5, Constant.GAME_WIDTH/2.8);

Planet earth = new Planet( "images/planet.jpg",

150, 100, 0.1, sun);

Planet moon = new Planet( "images/planet.jpg",

25, 10, 0.3, earth, true);

Planet mars = new Planet( "images/planet.jpg",

200, 130, 0.2, sun);

public void paint(Graphics g){

g.drawImage(bg,

0, 0, null);

sun.draw(g);

earth.draw(g);

moon.draw(g);

mars.draw(g);

}

public static void main(String[] args){

new

solarFrame().launchFrame();

}

//?????????利用双缓冲技术解决背景屏幕经常闪烁的问题

private Image

offScreenImage = null;

public void

update(Graphics g){

if

(offScreenImage == null)

offScreenImage

= this.createImage(Constant.GAME_WIDTH,

Constant.GAME_HEIGHT);

Graphics

gOff = offScreenImage.getGraphics();

paint(gOff);

g.drawImage(offScreenImage,

0, 0, null);

}

}

运行效果如下：