Android重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)); }}