修改nifest.xml增加：

<uses-feature android:name="android.hardware.sensor.proximity"  android:required="true"/>

代码：

SensorEventListener proximitySensorListener;
  SensorManager sensorManager;
  Sensor proximitySensor;

  private void initProximitySensor()
  {
      sensorManager =
              (SensorManager) getSystemService(SENSOR_SERVICE);
      proximitySensor =
              sensorManager.getDefaultSensor(Sensor.TYPE_PROXIMITY);

        proximitySensorListener = new SensorEventListener() {
           @Override
           public void onSensorChanged(SensorEvent sensorEvent) {
               if(sensorEvent.values[0] < proximitySensor.getMaximumRange()) {
                   //getWindow().getDecorView().setBackgroundColor(Color.RED);
               } else {
                   //getWindow().getDecorView().setBackgroundColor(Color.GREEN);
               }
           }

           @Override
           public void onAccuracyChanged(Sensor sensor, int i) {
           }
       };

       sensorManager.registerListener(proximitySensorListener,
               proximitySensor, 2 * 1000 * 1000);
  }