简易太阳系模型

此简易太阳系模型实现了日地月的二维运行轨迹，运行结果截图如下：

代码：
1.solar包
(1)星系类：
import java.awt.Graphics;
import java.awt.Image;
import util.Constant;
import util.GameUtil;
import util.MyFrame;

public class MySolarSystem extends MyFrame {
Image bg = GameUtil.getImage("images/bg.png");
Star sun = new Star("images/s.png",Constant.WIDTH/2,Constant.HEIGHT/2);
Planet earth = new Planet("images/e.png",sun,200,150,0.05);
Planet moon = new Planet("images/m.png",earth,50,40,0.15,true);

public void paint(Graphics g){
	g.drawImage(bg,0,0,null);
	sun.draw(g);
	earth.draw(g);
	moon.draw(g);
	
}

public static void main(String[] args){
	new MySolarSystem().launchFrame();
}

}
(2)恒星类：
import java.awt.Image;
import util.GameUtil;
import java.awt.Graphics;;

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(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);
	this.x  = x - this.width/2;
	this.y = y - this.height/2;
	
}
public Star(String imgpath, double x, double y){
	this(GameUtil.getImage(imgpath), x, y);
	
}

}
(3)行星类：
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Image;
import util.GameUtil;

public class Planet extends Star {
Star center;
double longAxis;
double shortAxis;
double speed;
double degree;
boolean stal;

public void draw(Graphics g) {
	super.draw(g);
	if(!stal){
		drawTrace(g);
	} 
	move();
}

public void drawTrace(Graphics g){
	double ovalX,ovalY,ovalWidth,ovalHeight;
	ovalX = center.x + center.width /2 - longAxis;
	ovalY = center.y + center.height /2 - shortAxis;
	ovalWidth = longAxis*2;
	ovalHeight = shortAxis*2;
	Color c= g.getColor();
	g.setColor(Color.yellow);
	g.drawOval((int)ovalX, (int)ovalY, (int)ovalWidth, (int)ovalHeight);
	g.setColor(c);
}

public void move() { 
	x = center.x + center.width/2 + longAxis*Math.cos(degree)- this.width/2;
	y = center.y + center.width/2 + shortAxis*Math.sin(degree) - this.height/2;
	degree += speed;
}

public Planet(String imgpath, Star center, double longAxis,
		double shortAxis, double speed) {
	super(GameUtil.getImage(imgpath));
	this.center = center;
	this.longAxis = longAxis;
	this.shortAxis = shortAxis;
	this.x = center.x + center.width/2 + longAxis - this.width/2;
	this.y = center.y + center.width/2 - this.height/2;
	this.speed = speed;
	}

public Planet(String imgpath, Star center, double longAxis,
		double shortAxis, double speed, boolean stal){
	this(imgpath, center, longAxis, shortAxis, speed);
	this.stal = stal;
}
 
public Planet(Image img, double x, double y) {
	super(img, x, y);
}

public Planet(String imgpath, double x, double y) {
	super(imgpath, x, y);
}

}
2.工具包
(1)工具类：
import java.awt.Image;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.net.URL;
import javax.imageio.ImageIO;

public class GameUtil {

private GameUtil(){}
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;
}

}
(2)框架类：
import java.awt.Frame;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;

public class MyFrame extends Frame {

public void launchFrame(){
	setSize(Constant.WIDTH, Constant.HEIGHT);
	setLocation(100, 100);
	setVisible(true);
	new PaintThread().start();  
	addWindowListener(new WindowAdapter(){
		public void windowClosing(WindowEvent e){
			System.exit(0);
		}
	});
}

class PaintThread extends Thread{
	public void run(){
		while(true){
			repaint();
			try {
				Thread.sleep(40);
			} catch (InterruptedException e) {
				e.printStackTrace();
			}
		}
	}
}

private Image offScreenImage = null;
public void update(Graphics g){
	if(offScreenImage == null){
		offScreenImage = this.createImage(Constant.WIDTH,Constant.HEIGHT);
		}
	Graphics gOff = offScreenImage.getGraphics();
	paint(gOff);
	g.drawImage(offScreenImage, 0, 0, null);
}

}
(3)常量类：
public class Constant {
public static final int WIDTH = 800;
public static final int HEIGHT = 800;
}
3.素材包
(1)背景：
(2)太阳：
(3)地球：
(4)月球：

此程序在高淇老师教学视频下完成