Java_太陽系_行星模型_小游戲練習_詳細注釋

//實現MyFrame--實現繪制窗口，和實現重寫 重畫窗口線程類

package cn.xiaocangtian.Test;

import java.awt.Frame;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;


public class MyFrame extends Frame {

        //加載窗口
        public void launchFrame() {
            setSize(Constant.GAME_WIDTH, Constant.GAME_HEIGHT);       //設置窗口大小
            setLocation(100, 100);   //設置左上角坐標，開始位置, 也就是窗口開始位置
            setVisible(true);        //設置為可見(默認為不可見)
            
            //啟動重畫線程
            new PaintThread().start();
            
            //匿名內部類---用來關閉窗口
            addWindowListener(new WindowAdapter() {
                @Override
                public void windowClosing(WindowEvent e) {
                    System.exit(0);
                }
            });
            
        }
        
        /**
         * 定義一個重畫窗口的線程類
         * 是一個內部類(方便訪問外部類屬性)
         */
        class PaintThread extends Thread {
            public void run() {
                while (true) {
                    repaint();             //重畫
                    try {
                        Thread.sleep(40);  //1s = 1000ms
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }  
                }
            }
        }
        
}

package cn.xiaocangtian.Util;

import java.awt.Image;
import java.awt.Toolkit;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.net.URL;

import javax.imageio.ImageIO;
import javax.swing.ImageIcon;

/**
 * 游戲開發中常用的工具類(比如:加載圖片等方法)
 * @author admin
 *
 */
public class GameUtil {
    
    private GameUtil () {} //工具類通常將構造方法私有
    
    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;  //BufferedImage是Image子類，也算正確返回
        return Toolkit.getDefaultToolkit().getImage(GameUtil.class.getClassLoader().getResource(path));
    }
}

package cn.xiaocangtian.Solar;

import java.awt.Graphics;
import java.awt.Image;

import cn.xiaocangtian.Util.GameUtil;

//封裝成類
//導入圖片
public class Star {
    Image img;                //用於導入圖片
    double x, y;              //圖片位置
    int width, height;        //圖片長寬
    
    public void draw(Graphics g) {
        g.drawImage(img, (int)x, (int)y, null);
    }
    
    public Star() {          //子類要調用父類的默認造函數
        
    }
    
    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.y = y;
        
    }
    
    //導入
    public Star(String imgpath, double x, double y) {
        this(GameUtil.getImage(imgpath), x, y);
    }
}

package cn.xiaocangtian.Util;

/**
 * 游戲項目中用到的常量
 * 單獨負責常量
 * @author admin
 */
public class Constant {
    
    public static final int GAME_WIDTH = 750;
    public static final int GAME_HEIGHT = 600;
    
}

package cn.xiaocangtian.Solar;

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Image;

import cn.xiaocangtian.Util.GameUtil;

public class Planet extends Star {
    
    //除了圖片，坐標，行星沿着某個橢圓運行：長軸，短軸，速度， 角度，繞着某個Star飛
    double longAxis;        //橢圓的長軸
    double shortAxis;       //橢圓的短軸
    double speed;           //飛行的速度
    double degree;          //角度
    Star center;            //中心
    boolean satillite;      //標志是否是衛星
    
    public void draw(Graphics g) {
        super.draw(g);
        move();
        if (!satillite) {   //不是衛星再畫出軌跡
            drawTrace(g);
        }
    }
    
    public void move() {
        //沿着橢圓飛
        x = (center.x + center.width/2) + longAxis * Math.cos(degree);
        y = (center.y + center.height/2) + shortAxis * Math.sin(degree);                
        //速度不一樣，所以增量也不同
        degree += speed;
    }
    
    //畫出行星的軌跡
    public void drawTrace(Graphics g) {
        double ovalX, ovalY, ovalWidth, ovalHeight;
        ovalHeight = longAxis * 2;                         //長度即為長軸*2
        ovalWidth = shortAxis * 2;
        ovalX = (center.x + center.width/2) - longAxis;    //左上頂點為(中心.x + x.width/2) - 長軸
        ovalY = (center.y + center.height/2) - shortAxis;
        
        Color oldColor = g.getColor();
        g.setColor(Color.blue);                            //設置軌跡顏色
        g.drawOval((int)ovalX, (int)ovalY, (int)ovalHeight, (int)ovalWidth);
        g.setColor(oldColor);
    }
    
    
    //需要調用父類的空構造器
    public Planet(Star center, String imgpath, double longAxis,
            double shortAxis, double speed) {
        super(GameUtil.getImage(imgpath));
        
        this.center = center;
        this.x = center.x + longAxis;         //行星的位置
        this.y = center.y;
        
        this.longAxis = longAxis;             //當前行星的長軸
        this.shortAxis = shortAxis;
        this.speed = speed;
        
        this.width = img.getWidth(null);
        this.height = img.getHeight(null);
    }

    public Planet(Star center, String imgpath, double longAxis,
            double shortAxis, double speed, boolean satellite) {
        this(center, imgpath, longAxis, shortAxis, speed);
        this.satillite = 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);
    }
    
}

package cn.xiaocangtian.Solar;

import java.awt.Graphics;
import java.awt.Image;

import cn.xiaocangtian.Util.Constant;
import cn.xiaocangtian.Util.GameUtil;
import cn.xiaocangtian.Util.MyFrame;

/**
 * 太陽系主窗口
 * @author admin
 *
 */
public class SolarFrame extends MyFrame {
    //導入背景
    Image bg = GameUtil.getImage("images/yuzhou.png");
    //這里是利用封裝的類，導入圖片
    Star sun = new Star("images/sun.png", Constant.GAME_WIDTH / 2, Constant.GAME_HEIGHT / 2);
    Planet earth = new Planet(sun, "images/polar.png", 150, 100, 0.1);
    Planet moon = new Planet(earth, "images/moon.png", 30, 20, 0.3, true);
    Planet Mars = new Planet(sun, "images/Mars.png", 200, 130, 0.2);
    
    /**
     * 可以繼續添加 其他 行星，只需一行代碼(已經封裝好)
     * ......
     * ......
     * ......
     */
    
    /**
     * 重寫重繪函數，此為回調函數，只需要實現，然后由系統自動調用
     */
    public void paint(Graphics g) {
        g.drawImage(bg, 0, 0, null);
        sun.draw(g);       //這里使用的是封裝的方法
        earth.draw(g);
        moon.draw(g);
        Mars.draw(g);
        
        /***
         * 還可以繼續添加其他行星並繪制
         * ..........
         * ..........
         * ..........
         */
    }
    
    public static void main(String[] args) {
        new SolarFrame().launchFrame();
    }
}

//本程序只添加了太陽，地球，月球，火星，其余可以自行添加，使用封裝好的方法，只用十分簡潔的代碼即可