安卓:如何获得设备目前面临的方向，类似于谷歌地图

Question

我目前正在使用定位服务来获取用户的位置以及通过Geocoder获取地址。

我存储了这些数据以便以后显示。同时，我想保存应用程序定位时他们所面对的方向。

谷歌地图在旅行时是否使用指南针API来处理它，或者是否有我错过的任何其他android库。

我怀疑它使用了Compass Api，因为当我尝试安装Compass应用程序时，我的手机没有传感器。

Answer 1

您可以使用位置传感器：

public class SensorActivity extends Activity implements SensorEventListener {
private SensorManager sensorManager;
private final float[] accelerometerReading = new float[3];
private final float[] magnetometerReading = new float[3];
private final float[] rotationMatrix = new float[9];
private final float[] orientationAngles = new float[3];
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
sensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
}
@Override
public void onAccuracyChanged(Sensor sensor, int accuracy) {
// Do something here if sensor accuracy changes.
// You must implement this callback in your code.
}
@Override
protected void onResume() {
super.onResume();
// Get updates from the accelerometer and magnetometer at a constant rate.
// To make batch operations more efficient and reduce power consumption,
// provide support for delaying updates to the application.
//
// In this example, the sensor reporting delay is small enough such that
// the application receives an update before the system checks the sensor
// readings again.
Sensor accelerometer = sensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
if (accelerometer != null) {
sensorManager.registerListener(this, accelerometer,
SensorManager.SENSOR_DELAY_NORMAL, SensorManager.SENSOR_DELAY_UI);
}
Sensor magneticField = sensorManager.getDefaultSensor(Sensor.TYPE_MAGNETIC_FIELD);
if (magneticField != null) {
sensorManager.registerListener(this, magneticField,
SensorManager.SENSOR_DELAY_NORMAL, SensorManager.SENSOR_DELAY_UI);
}
}
@Override
protected void onPause() {
super.onPause();
// Don't receive any more updates from either sensor.
sensorManager.unregisterListener(this);
}
// Get readings from accelerometer and magnetometer. To simplify calculations,
// consider storing these readings as unit vectors.
@Override
public void onSensorChanged(SensorEvent event) {
if (event.sensor.getType() == Sensor.TYPE_ACCELEROMETER) {
System.arraycopy(event.values, 0, accelerometerReading,
0, accelerometerReading.length);
} else if (event.sensor.getType() == Sensor.TYPE_MAGNETIC_FIELD) {
System.arraycopy(event.values, 0, magnetometerReading,
0, magnetometerReading.length);
}
}
// Compute the three orientation angles based on the most recent readings from
// the device's accelerometer and magnetometer.
public void updateOrientationAngles() {
// Update rotation matrix, which is needed to update orientation angles.
SensorManager.getRotationMatrix(rotationMatrix, null,
accelerometerReading, magnetometerReading);
// "rotationMatrix" now has up-to-date information.
SensorManager.getOrientation(rotationMatrix, orientationAngles);
// "orientationAngles" now has up-to-date information.
}
}

加速度计(7.3.1.(和磁强计(7.3.2.(都是"；强烈推荐"；安卓兼容性定义中，并且很可能存在于您的设备中。