Java图形界面编程学习Demo---太阳系行星运转轨迹图

package cn.com.solar; import java.awt.Color; import java.awt.Graphics; import java.awt.Image; import cn.com.util.GameUtil; public class Planet extends Star{ //除了图片，坐标。行星沿着某个椭圆运行：长轴、短轴、速度。绕着某个Strat飞。 double longAxis;//椭圆的长轴 double shortAxis;//椭圆的短轴 double speed; double degree; Star center; boolean satellite;//判断是否是卫星，若是，则不画轨迹 //重写父类的draw方法 public void draw(Graphics g){ super.draw(g); move(); if(!satellite){ drawTrace(g); } } 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 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 color=g.getColor(); g.setColor(Color.BLUE); g.drawOval((int)ovalX, (int)ovalY, (int)ovalWidth, (int)ovalHeight); g.setColor(color); } public Planet(Star center,String imgpath,double longAxis,double shortAxis,double speed){ super(GameUtil.getImage(imgpath)); this.center=center; this.x=center.x+longAxis; this.y=center.y; this.longAxis =longAxis; this.shortAxis=shortAxis; this.speed=speed; } public Planet(Star center,String imgpath,double longAxis,double shortAxis,double speed,boolean satellite){ this(center, imgpath, longAxis, shortAxis, speed); this.satellite=satellite; } public Planet(Image img,double x,double y){ super(img, x, y); } public Planet(String imgpath,double x,double y){ super(imgpath, x, y); } }