Android传感器应用——地心引力传感器实现滚动的弹球

public class MySurfaceView extends SurfaceView implements Callback, Runnable {    private SurfaceHolder sfh;    private Paint paint;    private Thread th;    private boolean flag;    private Canvas canvas;    private int screenW, screenH;        //声明一个传感器管理器        private SensorManager sm;        //声明一个传感器        private Sensor sensor;        //声明一个传感器监听器        private SensorEventListener mySensorListener;        //圆形的X,Y坐标        private int arc_x, arc_y;        //传感器的xyz值        private float x = 0, y = 0, z = 0;    /**     * SurfaceView初始化函数     */    public MySurfaceView(Context context) {        super(context);        sfh = this.getHolder();        sfh.addCallback(this);        paint = new Paint();        paint.setColor(Color.WHITE);        paint.setAntiAlias(true);        setFocusable(true);        //获取传感器管理类实例        sm = (SensorManager) MainActivity.instance.getSystemService(Service.SENSOR_SERVICE);        //实例一个重力传感器实例          sensor = sm.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);        //实例传感器监听器        mySensorListener = new SensorEventListener() {            @Override            //传感器获取值发生改变时在响应此函数              public void onSensorChanged(SensorEvent event) {                x = event.values[0];                 //x>0 说明当前手机左翻 x<0右翻                       y = event.values[1];                //y>0 说明当前手机下翻 y<0上翻                  z = event.values[2];                 //z>0 手机屏幕朝上 z<0 手机屏幕朝下                  arc_x -= x;                arc_y += y;            }            @Override            //传感器的精度发生改变时响应此函数              public void onAccuracyChanged(Sensor sensor, int accuracy) {            }        };        //为传感器注册监听器        sm.registerListener(mySensorListener, sensor, SensorManager.SENSOR_DELAY_GAME);            }    /**     * SurfaceView视图创建，响应此函数     */    @Override    public void surfaceCreated(SurfaceHolder holder) {        screenW = this.getWidth();        screenH = this.getHeight();        flag = true;        //实例线程        th = new Thread(this);        //启动线程        th.start();    }    /**     * 游戏绘图     */    public void myDraw() {        try {            canvas = sfh.lockCanvas();            if (canvas != null) {                canvas.drawColor(Color.BLACK);                paint.setColor(Color.RED);                canvas.drawArc(new RectF(arc_x, arc_y, arc_x + 50, arc_y + 50), 0, 360, true, paint);                paint.setColor(Color.YELLOW);                canvas.drawText("当前重力传感器的值:", arc_x - 50, arc_y - 30, paint);                canvas.drawText("x=" + x + ",y=" + y + ",z=" + z, arc_x - 50, arc_y, paint);                String temp_str = "tony提示： ";                String temp_str2 = "";                String temp_str3 = "";                if (x < 1 && x > -1 && y < 1 && y > -1) {                    temp_str += "当前手机处于水平放置的状态";                    if (z > 0) {                        temp_str2 += "并且屏幕朝上";                    } else {                        temp_str2 += "并且屏幕朝下,提示别躺着玩手机，对眼睛不好哟~";                    }                } else {                    if (x > 1) {                        temp_str2 += "当前手机处于向左翻的状态";                    } else if (x < -1) {                        temp_str2 += "当前手机处于向右翻的状态";                    }                    if (y > 1) {                        temp_str2 += "当前手机处于向下翻的状态";                    } else if (y < -1) {                        temp_str2 += "当前手机处于向上翻的状态";                    }                    if (z > 0) {                        temp_str3 += "并且屏幕朝上";                    } else {                        temp_str3 += "并且屏幕朝下,提示别躺着玩手机，对眼睛不好哟~";                    }                }                paint.setTextSize(10);                canvas.drawText(temp_str, 0, 50, paint);                canvas.drawText(temp_str2, 0, 80, paint);                canvas.drawText(temp_str3, 0, 110, paint);            }        } catch (Exception e) {            // TODO: handle exception        } finally {            if (canvas != null)                sfh.unlockCanvasAndPost(canvas);        }    }    /**     * 触屏事件监听     */    @Override    public boolean onTouchEvent(MotionEvent event) {        return true;    }    /**     * 按键事件监听     */    @Override    public boolean onKeyDown(int keyCode, KeyEvent event) {        return super.onKeyDown(keyCode, event);    }    /**     * 游戏逻辑     */    private void logic() {    }    @Override    public void run() {        while (flag) {            long start = System.currentTimeMillis();            myDraw();            logic();            long end = System.currentTimeMillis();            try {                if (end - start < 50) {                    Thread.sleep(50 - (end - start));                }            } catch (InterruptedException e) {                e.printStackTrace();            }        }    }    /**     * SurfaceView视图状态发生改变，响应此函数     */    @Override    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {    }    /**     * SurfaceView视图消亡时，响应此函数     */    @Override    public void surfaceDestroyed(SurfaceHolder holder) {        flag = false;    }}

public class MainActivity extends Activity {    public static MainActivity instance;    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        instance = this;        //设置全屏        this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);        requestWindowFeature(Window.FEATURE_NO_TITLE);        //显示自定义的SurfaceView视图        setContentView(new MySurfaceView(this));    }}