Android-Environment Sensors

The Android platform provides four sensors that let you monitor various environmental properties. You can use these sensors to monitor relative ambient humidity, illuminance, ambient
pressure, and ambient temperature near an Android-powered device.

》Using the Light, Pressure, and Temperature Sensors

Then you register a sensor listener in the

onResume()

method, and start handling
incoming sensor data in the

onSensorChanged()

callback
method. The following code shows you how to do this:

public class SensorActivity extends Activity implements SensorEventListener {
private SensorManager mSensorManager;
private Sensor mPressure;

@Override
public final void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);

// Get an instance of the sensor service, and use that to get an instance of
// a particular sensor.
mSensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
mPressure = mSensorManager.getDefaultSensor(Sensor.TYPE_PRESSURE);
}

@Override
public final void onAccuracyChanged(Sensor sensor, int accuracy) {
// Do something here if sensor accuracy changes.
}

@Override
public final void onSensorChanged(SensorEvent event) {
float millibars_of_pressure = event.values[0];
// Do something with this sensor data.
}

@Override
protected void onResume() {
// Register a listener for the sensor.
super.onResume();
mSensorManager.registerListener(this, mPressure, SensorManager.SENSOR_DELAY_NORMAL);
}

@Override
protected void onPause() {
// Be sure to unregister the sensor when the activity pauses.
super.onPause();
mSensorManager.unregisterListener(this);
}
}

》Using the Humidity（湿度） Sensor
You can acquire raw relative humidity data by using the humidity sensor the same way that you use
the light, pressure, and temperature sensors. However, if a device has both a humidity sensor (

TYPE_RELATIVE_HUMIDITY

)
and a temperature sensor (

TYPE_AMBIENT_TEMPERATURE

)
you can use these two data streams to calculate the dew point and the absolute humidity.