电子罗盘(方向传感器)

public class MainActivity extends AppCompatActivity {

    private SensorManager sensorManager;
    private Sensor magneticSensor;
    private Sensor accelerometerSensor;
    private SensorEventListener listener;
    private TextView mTv;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mTv = (TextView) findViewById(R.id.show_text_view);
        sensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
        magneticSensor = sensorManager.getDefaultSensor(Sensor.TYPE_MAGNETIC_FIELD);
        accelerometerSensor = sensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
        listener = new SensorEventListener() {
            float[] accelerometerValues = new float[3];
            float[] magneticValues = new float[3];

            @Override
            public void onSensorChanged(SensorEvent event) {
                // 判断当前是加速度传感器还是地磁传感器
                if (event.sensor.getType() == Sensor.TYPE_ACCELEROMETER) {
                    // 注意赋值时要调用clone()方法
                    accelerometerValues = event.values.clone();
                } else if (event.sensor.getType() == Sensor.TYPE_MAGNETIC_FIELD) {
                    magneticValues = event.values.clone();
                }
                float[] R = new float[9];
                float[] values = new float[3];
                SensorManager.getRotationMatrix(R, null, accelerometerValues, magneticValues);
                SensorManager.getOrientation(R, values);
                /**
                 * 0度 正北
                 * +-180度 正南
                 * -90度 正西
                 * 90度 正东
                 */
                mTv.setText("当前角度为:" + Math.toDegrees(values[0]));
            }

            @Override
            public void onAccuracyChanged(Sensor sensor, int accuracy) {

            }
        };
        sensorManager.registerListener(listener, magneticSensor, SensorManager.SENSOR_DELAY_NORMAL);
        sensorManager.registerListener(listener, accelerometerSensor, SensorManager.SENSOR_DELAY_NORMAL);

    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        if (sensorManager != null) {
            sensorManager.unregisterListener(listener);
        }
    }
}