初学Android,图形图像之打砖块游戏(二十八)

这个弹球游戏是没有砖块的打砖块游戏，简版，效果如下

package WangLi.Graphics.PinBall;

import java.util.Random;
import java.util.Timer;
import java.util.TimerTask;

import android.app.Activity;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.Display;
import android.view.KeyEvent;
import android.view.View;
import android.view.View.OnKeyListener;
import android.view.Window;
import android.view.WindowManager;

public class PinBall extends Activity {
	class GameView extends View
	{
		public GameView(Context context) {
			super(context);
			setFocusable(true);
		}
		//重写View的onDraw方法,实现绘画
		public void onDraw(Canvas canvas)
		{
			Paint paint = new Paint();
			paint.setStyle(Paint.Style.FILL);
			//如果游戏已经结束
			if(isLose)
			{
				paint.setColor(Color.RED);
				paint.setTextSize(40);
				canvas.drawText("游戏已结束", 50, 200, paint);
			}
			//如果游戏还未结束
			else
			{
				//设置颜色,并绘制小球　
				paint.setColor(Color.rgb(240, 240, 80));
				canvas.drawCircle(ballX, ballY, BALL_SIZE, paint);
				//设置颜色,并绘制小球
				paint.setColor(Color.rgb(80, 80, 200));
				canvas.drawRect(racketX, racketY, racketX + RACKET_WIDTH,
						racketY + RACKET_HEIGHT, paint);
			}
		}
	}
	
    /** Called when the activity is first created. */
	//桌面的宽度
	private int tableWidth;
	//桌面的高度
	private int tableHeight;
	//球拍的垂直位置
	private int racketY;
	//定义球拍的高度和宽度
	private final int RACKET_HEIGHT = 20;
	private final int RACKET_WIDTH = 70;
	//小球的大小
	private final int BALL_SIZE = 12;
	//小球纵向的运行速度
	private int ySpeed = 10;
	Random rand = new Random();
	//返回一个-0.5~0.5比率,用于控制小球的运行方向
	private double xyRate = rand.nextDouble() - 0.5;
	//小球横向的运行速度
	private int xSpeed = (int)(ySpeed * xyRate * 2);
	//ballX和ballY代表小球坐标
	private int ballX = rand.nextInt(200) + 20;
	private int ballY = rand.nextInt(10) + 20;
	//racketX代表球拍的水平位置
	private int racketX = rand.nextInt(200);
	//游戏是否结束的旗标
	private boolean isLose = false;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //去掉窗口标题
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        //全屏显示
        getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
        		WindowManager.LayoutParams.FLAG_FULLSCREEN);
        //创建GameView组件
        final GameView gameView = new GameView(this);
        setContentView(gameView);
        //获取窗口管理器
        WindowManager windowManager = getWindowManager();
        Display display = windowManager.getDefaultDisplay();
        //获取屏幕宽和高
        tableWidth = display.getWidth();
        tableHeight = display.getHeight();
        racketY = tableHeight - 80;
        final Handler handler = new Handler()
        {
        	public void handleMessage(Message msg)
        	{
        		if(msg.what == 0x123)
        		{
        			gameView.invalidate();
        		}
        	}
        };
        gameView.setOnKeyListener(new OnKeyListener()
        {
        	public boolean onKey(View source,int keyCode,KeyEvent event)
        	{
        		//获取由哪个键触发事件
        		switch(event.getKeyCode())
        		{
        		      //控制挡板左移
        		      case KeyEvent.KEYCODE_DPAD_LEFT:
        		    	  if(racketX > 0)
        		    		  racketX -= 10;
        		    	  break;
        		      //控制挡板右移
        		      case KeyEvent.KEYCODE_DPAD_RIGHT:
        		    	  //判断是否已移到最右端
        		    	  if(racketX < tableWidth - RACKET_WIDTH)
        		    		  racketX += 10;
        		    	  break;
        		}
        		//通知gameView组件重绘
        		gameView.invalidate();
        		return true;
        	}
        });
        final Timer timer = new Timer();
        timer.schedule(new TimerTask()
        {
        	public void run()
        	{
               	//如果小球碰到左边边框
            	if(ballX <= 0 || ballX >= tableWidth - BALL_SIZE)
            	{
            		xSpeed = -xSpeed;
            	}
            	//如果小球高度超出了球拍位置,且横向不在球拍范围之内,游戏结束
            	if(ballY >= racketY - BALL_SIZE && (ballX < racketX || ballX > racketX + RACKET_WIDTH))
            	{
            		timer.cancel();
            		//设置游戏是否结束的旗标为true
            		isLose = true;
            	}
            	//如果小球位于球拍之内,且到达球拍位置,小球反弹
            	else if(ballY <= 0 || (ballY > racketY - BALL_SIZE && ballX > racketX && ballX <= racketX + RACKET_WIDTH))
            	{
            		ySpeed = -ySpeed;
            	}
            	//小球坐标增加
            	ballY += ySpeed;
            	ballX += xSpeed;
            	//发送消息,通知系统重绘
            	handler.sendEmptyMessage(0x123);
        	}
        }, 0, 100);
    }
}