android中如何使用方向传感器Sensor

传感器：方向 、重力、磁场、温度、近距离、压力、光线、加速度
下面是如何使用方向传感器（指南针）：
使用自定义view画出指南针

public class MainActivity extends Activity
{
private SensorManager manager;
private Sensor mSensor;
float[] mValues;
private SampleView mView;
@SuppressWarnings("deprecation")
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
mView = new SampleView(this);//使用自定义view
setContentView(mView);
//得到传感器管理器
manager = (SensorManager)                         getSystemService(Context.SENSOR_SERVICE);
//得到方向传感器
mSensor = manager.getDefaultSensor(Sensor.TYPE_ORIENTATION);
}
SensorEventListener mListener = new SensorEventListener()
{
@Override
public void onSensorChanged(SensorEvent event)
{
mValues = event.values;
if (mView != null)
{
mView.invalidate();//event发生改变时，重绘
}
}
@Override
public void onAccuracyChanged(Sensor sensor, int accuracy)
{
//精确改变，适用游戏
}
};
@Override
protected void onStart()
{
super.onStart();
//在onstart()或onresume()里,管理器注册监听事件
manager.registerListener(mListener, mSensor,             SensorManager.SENSOR_DELAY_GAME);
}
@Override
public boolean onCreateOptionsMenu(Menu menu)
{
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
private class SampleView extends View
{
private Paint   mPaint = new Paint();
private Path    mPath = new Path();
private boolean mAnimate;
private long    mNextTime;
public SampleView(Context context)
{
super(context);
// Construct a wedge-shaped path
mPath.moveTo(0, -50);
mPath.lineTo(-20, 60);
mPath.lineTo(0, 50);
mPath.lineTo(20, 60);
mPath.close();
}
@Override protected void onDraw(Canvas canvas)
{
Paint paint = mPaint;
canvas.drawColor(Color.WHITE);
paint.setAntiAlias(true);
paint.setColor(Color.BLACK);
paint.setStyle(Paint.Style.FILL);
int w = canvas.getWidth();
int h = canvas.getHeight();
int cx = w / 2;
int cy = h / 2;
canvas.translate(cx, cy);
if (mValues != null)
{
canvas.rotate(-mValues[0]);
}
canvas.drawPath(mPath, mPaint);
}
@Override
protected void onAttachedToWindow()
{
mAnimate = true;
super.onAttachedToWindow();
}
@Override
protected void onDetachedFromWindow()
{
mAnimate = false;
super.onDetachedFromWindow();
}
}
}

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