android-如何实时监视设备的方向？

Question

I want to monitor the orientation of the android device just in realtime (I mean continually and retrieve new orientation as fast as possible). I use the combination of ACCELEROMETER and MAGNETIC_FIELD and have tow listeners for the changes that happen to those tow sensors. now where to put these 2 lines of code to get the orientation?

SensorManager.getRotationMatrix(R, null, aValues, mValues);
SensorManager.getOrientation(R, values);

I made a background Thread and put that code in an infinite for loop ...is it a good implementation?

    ExecutorService executor = Executors.newCachedThreadPool();
    executor.execute(new Runnable() {

        @Override
        public void run() {
            for (;;) {
                SensorManager.getRotationMatrix(R, null, aValues, mValues);
                SensorManager.getOrientation(R, values);
                      }
                          }
                                    }

Answer 1

You should use the SensorEventListener

private final SensorEventListener mSensorListener = new SensorEventListener() {

    public void onSensorChanged(SensorEvent se) {
      float x = se.values[0];
      float y = se.values[1];
      float z = se.values[2];
      mAccelLast = mAccelCurrent;
      mAccelCurrent = (float) Math.sqrt((double) (x*x + y*y + z*z));
      float delta = mAccelCurrent - mAccelLast;
      mAccel = mAccel * 0.9f + delta; // perform low-cut filter
    }

    public void onAccuracyChanged(Sensor sensor, int accuracy) {
    }
};

On your Activity you have to import:

private SensorManager mSensorManager;
private float mAccel; // acceleration apart from gravity
private float mAccelCurrent; // current acceleration including gravity
private float mAccelLast; // last acceleration including gravity

And to initialize:

mSensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
mSensorManager.registerListener(mSensorListener, mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER), SensorManager.SENSOR_DELAY_NORMAL);
mAccel = 0.00f;
mAccelCurrent = SensorManager.GRAVITY_EARTH;
mAccelLast = SensorManager.GRAVITY_EARTH;