从最简单的源代码开始,切勿眼高手低—(第一波)

大家好，又见面了，我是全栈君。

        从正式学习安卓到现在,差不多整整一年了,去年暑假,大约也就是6,7月份的样子,从图书馆借了好多书,安卓的,java的,假期里算是把李刚的<疯狂安卓讲义>完完整整的看完了,当时就只顾着看书,很少敲代码,也没做笔记,凭着脑子看,看完感觉收获还是挺大的,又看了mars老师的视频,没看完,大约看了第一季十几集差不多,终归停留在好像懂了的层面,也没做什么东西.

        暑假过后,断断续续的学一点,发现java有点薄弱,毕竟没系统的学过,寒假之后到前段时间系统的把java过了一遍.到这时候我开始意识到做笔记和敲代码的重要性了,不做笔记,很快就会把当时明白的知识点遗忘掉,不敲代码,等真正用到的时候不知道怎么下手.

直到前段时间,自己亲手写了个小游戏,我才真正体会到学习的乐趣.还是要多实际的去操作才行.期末了,忙着各种考试,也有点迷茫接下来该怎么继续学习,感觉自己挺懂了,其实大多还是眼高手低.前天,碰巧在安卓巴士上找到一个别人分享的文件,里面是二十来个游戏的源代码,有点如获至宝的感觉啊.

于是按照从小到大的顺序排列了下来,打算现在开始加上暑假,挨着看一遍,自己实现一遍.

最小的一个便是下面这个.界面就是下面一个挡板,可控制左右移动,把下落的球弹上去.很常见的一个案例.看了一遍源代码,大体自己重写了一遍.收货真的很大,以后写完一个贴上来一个,也算是给代码做个笔记.

如果你也是新手,一定要多写.自己多写.亲手写.

下面是源码

public class PinBall extends Activity{
	
	private int tableHeight;
	private int tableWidth;
	Random random = new Random();
	
	//挡板大小和坐标
	private final int racket_width = 70;
	private final int racket_height = 20;
	private int racketY;
	private int racketX;
	
    //球体大小,速度,坐标
	private final int ballR = 12;
	private int ballX;
	private int ballY;
	private int Vy = 3;
	//生成一个比率(-0.5~0.5之间),用于产生随机方向
	private double xyRate = random.nextDouble() - 0.5;
	private int Vx = (int) (Vy * 2 * xyRate); 
	
	//游戏进行时标志
	private boolean isLose = false;
	
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		// TODO Auto-generated method stub
		super.onCreate(savedInstanceState);
		//全屏无标题
		requestWindowFeature(Window.FEATURE_NO_TITLE);
		getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, 
				WindowManager.LayoutParams.FLAG_FULLSCREEN);
		//设置游戏界面
		final GameView game = new  GameView(this);
		setContentView(game);
		//获取桌面大小
		WindowManager manager = getWindowManager();
		Display display = manager.getDefaultDisplay();
		tableHeight = display.getHeight();
		tableWidth = display.getWidth();
		//根据获取的桌面大小初始化坐标
		initXY();
		
		//重绘
		final Handler handler = new Handler(){
			public void handleMessage(Message message){
				if(message.what == 0x123){
					game.invalidate();
				}
			}
		};
		
		final Timer timer = new Timer();
		timer.schedule(new TimerTask() {
			
			@Override
			public void run() {
				//左右边框
				if(ballX < 0 || (ballX + ballR > tableWidth)){
					Vx = -Vx;
				}
				//超过下边界且未被球拍接住
				if((ballY + ballR > racketY) && (ballX + ballR < racketX || ballX > racketX + racket_width)){
					timer.cancel();
					isLose = true;
				}
				//被球拍打回或者反弹时到达顶部
				if(ballY < 0 || (ballY + ballR > racketY && ballX > racketX && ballX < racketX + racket_width )){
					Vy = -Vy;
				}
				ballX += Vx;
				ballY += Vy;
				handler.sendEmptyMessage(0x123);
			}
		}, 0, 10);
		
		//给游戏view加监听器
		game.setOnTouchListener(new OnTouchListener() {
			
			@Override
			public boolean onTouch(View v, MotionEvent event) {
				int x = (int) event.getX();
				int mid = tableWidth/2;
				switch (x > mid ? 1 : 2) {
				case 1:
					if(racketX + racket_width < tableWidth){
						racketX += 10;	
					}
					break;
				case 2:
					if(racketX > 0){
						racketX -= 10;
					}
					break;
				}
				game.invalidate();
				return true;
			}
		});
		
	}
	
	private void initXY(){
		racketY = tableHeight - 80;
		racketX = random.nextInt(tableWidth);
		ballX = random.nextInt(tableWidth);
		ballY = random.nextInt(10) + 20;
	}
	
	class GameView extends View{

		private static final float TEXT_SIZE = 40;

		public GameView(Context context) {
			super(context);
			// TODO Auto-generated constructor stub
			setFocusable(true);
		}

		@Override
		protected void onDraw(Canvas canvas) {
			Paint paint = new Paint();
			paint.setStyle(Paint.Style.FILL);
			//游戏结束
			if (isLose) {
				paint.setTextSize(TEXT_SIZE);
				paint.setColor(Color.RED);
				canvas.drawText("Game Over!", tableWidth/2 - paint.getTextSize()*2, tableHeight/2 - paint.getTextSize()/2, paint);
			}
			//游戏继续
			else {
				paint.setColor(Color.BLUE);
				canvas.drawCircle(ballX, ballY, ballR, paint);
				paint.setColor(Color.GREEN);
				canvas.drawRect(racketX, racketY, racketX + racket_width, racketY + racket_height, paint);
				
			}
		}
		
		
	}
}