教你如何一步一步用Java实现飞机大战（一）

飞机大战第一天

1.抽象类：飞行物

public abstract class FlyingObject{
protected BufferedImage image;
protected int width;  //宽
protected int height; //高
protected int x; //x坐标

protected int y; 

//y坐标}

2.接口：敌人

public interface Enemy {
	/** 得分 */
	public int getScore();
}

3.接口：奖励

/** 奖励 */
public interface Award {
	public int DOUBLE_FIRE = 0; //火力值
	public int LIFE = 1; //命
	/** 获取奖励类型(上面的0或1) */
	public int getType();
}

4.敌机，飞行物，也是敌人

public class Airplane extends FlyingObject implements Enemy {
	private int speed = 2; //移动的速度
	/** 构造方法 */
	public Airplane(){
		image = ShootGame.airplane; //图片
		width = image.getWidth();   //宽
		height = image.getHeight(); //高
		Random rand = new Random(); //随机数对象
		x = rand.nextInt(ShootGame.WIDTH-this.width); //x:0到(窗口宽-敌机宽)之间的随机数
		y = -this.height; //y:负的敌机的高
	}
	
	/** 重写getScore()得分 */
	public int getScore(){
		return 5; //打掉一个敌机得5分
	}}

5.小蜜蜂：飞行物同时是也是奖励

/** 小蜜蜂: 是飞行物， */
public class Bee extends FlyingObject implements Award {
	private int xSpeed = 1; //x坐标移动速度
	private int ySpeed = 2; //y坐标移动速度
	private int awardType;  //奖励的类型(0或1)
	/** 构造方法 */
	public Bee(){
		image = ShootGame.bee; //图片
		width = image.getWidth();   //宽
		height = image.getHeight(); //高
		Random rand = new Random(); //随机数对象
		x = rand.nextInt(ShootGame.WIDTH-this.width); //x:0到(窗口宽-小蜜蜂宽)之间的随机数
		y = -this.height; //y:负的小蜜蜂的高
		awardType = rand.nextInt(2); //0和1之间的随机数
	}
	
	/** 获取奖励类型 */
	public int getType(){
		return awardType; //返回奖励类型
	}
}

6.子弹：同样也是飞行物

/** 子弹: 是飞行物 */
public class Bullet extends FlyingObject {
	private int speed = 3; //移动的速度
	/** 构造方法 子弹的初始坐标随着英雄机定*/
	public Bullet(int x,int y){
		image = ShootGame.bullet; //图片
		width = image.getWidth();   //宽
		height = image.getHeight(); //高
		this.x = x; //x:随英雄机
		this.y = y; //y:随英雄机
	}

7.英雄机：飞行物

/** 英雄机: 是飞行物 */
public class Hero extends FlyingObject {
	private int doubleFire; //火力值
	private int life; //命
	private BufferedImage[] images; //可切换的图片数组
	private int index; //协助图片切换
	/** 构造方法 */
	public Hero(){
		image = ShootGame.hero0; //图片
		width = image.getWidth();   //宽
		height = image.getHeight(); //高
		x = 150; //x:固定的值
		y = 400; //y:固定的值
		doubleFire = 10000; //默认为0(单倍火力)
		life = 3; //默认3条命
		images = new BufferedImage[]{ShootGame.hero0,ShootGame.hero1}; //两张图片切换
		index = 0; //协助图片切换
	}
}

8.主类：窗口

//主窗口类
public class ShootGame extends JPanel {
	public static final int WIDTH = 400;  //窗口宽
	public static final int HEIGHT = 654; //窗口高
	
	public static BufferedImage background; //背景图
	public static BufferedImage start;   	//启动图
	public static BufferedImage pause;		//暂停图
	public static BufferedImage gameover;	//游戏结束图
	public static BufferedImage airplane;	//敌机
	public static BufferedImage bee;		//小蜜蜂
	public static BufferedImage bullet;		//子弹
	public static BufferedImage hero0;		//英雄机0
	public static BufferedImage hero1;		//英雄机1
	static{ //初始化静态图片
		try{
			background = ImageIO.read(ShootGame.class.getResource("background.png"));
			start = ImageIO.read(ShootGame.class.getResource("start.png"));
			pause = ImageIO.read(ShootGame.class.getResource("pause.png"));
			gameover = ImageIO.read(ShootGame.class.getResource("gameover.png"));
			airplane = ImageIO.read(ShootGame.class.getResource("airplane.png"));
			bee = ImageIO.read(ShootGame.class.getResource("bee.png"));
			bullet = ImageIO.read(ShootGame.class.getResource("bullet.png"));
			hero0 = ImageIO.read(ShootGame.class.getResource("hero0.png"));
			hero1 = ImageIO.read(ShootGame.class.getResource("hero1.png"));
		}catch(Exception e){
			e.printStackTrace();
		}
	}
	
	private Hero hero = new Hero(); //一个英雄机
	private FlyingObject[] flyings = {}; //一堆敌人(敌机+小蜜蜂)
	private Bullet[] bullets = {}; //一堆子弹
	
	public static final int START = 0;     //启动状态
	public static final int RUNNING = 1;   //运行状态
	public static final int PAUSE = 2;     //暂停状态
	public static final int GAME_OVER = 3; //游戏结束状态
	private int state = START; //当前状态(默认启动状态)
public static void main(String[] args) {
		JFrame frame = new JFrame("Fly"); //创建窗口对象
		ShootGame game = new ShootGame(); //创建面板对象
		frame.add(game); //将面板添加到窗口中
		frame.setSize(WIDTH, HEIGHT); //设置窗口大小
		frame.setAlwaysOnTop(true); //设置总是在最上面
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //设置窗口默认关闭操作(关闭窗口时退出程序)
		frame.setLocationRelativeTo(null); //设置居中显示
		frame.setVisible(true); //1)设置窗口可见  2)尽快调用paint()方法
		
		game.action(); //启动程序的执行
	}
/** 重写paint() g:画笔*/
	public void paint(Graphics g){
		g.drawImage(background,0,0,null); //画背景图
		paintHero(g); //画英雄机对象
		paintFlyingObjects(g); //画敌人(敌机+小蜜蜂)对象
		paintBullets(g); //画子弹对象
		paintScoreAndLife(g); //画分和画命
		paintState(g); //画状态
	}
	/** 画英雄机对象 */
	public void paintHero(Graphics g){
		g.drawImage(hero.image,hero.x,hero.y,null); //画英雄机对象
	}
	/** 画敌人(敌机+小蜜蜂)对象 */
	public void paintFlyingObjects(Graphics g){
		for(int i=0;i<flyings.length;i++){ //遍历所有敌人(敌机+小蜜蜂)
			FlyingObject f = flyings[i]; //获取每一个敌人(敌机+小蜜蜂)
			g.drawImage(f.image,f.x,f.y,null); //画敌人(敌机+小蜜蜂)对象
		}
	}
	/** 画子弹对象 */
	public void paintBullets(Graphics g){
		for(int i=0;i<bullets.length;i++){ //遍历所有子弹
			Bullet b = bullets[i]; //获取每一个子弹
			g.drawImage(b.image,b.x,b.y,null); //画子弹对象
		}
	}
}

9.敌人入场的实现步骤：

1)main(){ game.action(); }
  2)action(){
      ...
      run(){ //10毫秒定时执行
        enteredAction(); //敌人入场
	    repaint();
      }
    }
  3)int index = 0;
    enteredAction(){ //10毫秒
      index++;
      if(index%40==0){  //40*10毫秒
        FlyingObject one = nextOne(); //创建一个敌人对象
        flyings = Arrays.copyOf(flyings,flyings.length+1); //扩容
        flyings[flyings.length-1] = one; //将敌人对象添加到敌人数组中
      }
    }
  4)nextOne(){
      生成0到19间的随机数
      为0时return new Bee();
      否则return new Airplane();
    }