import android.content.Context;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.util.Log;
public class LightSensorManager {
  private static final boolean DEBUG = true;
  private static final String TAG = "LightSensor";
  private static LightSensorManager instance;
  private SensorManager mSensorManager;
  private LightSensorListener mLightSensorListener;
  private boolean mHasStarted = false;
  private LightSensorManager() {
  }
  public static LightSensorManager getInstance() {
    if (instance == null) {
      instance = new LightSensorManager();
    }
    return instance;
  }
  public void start(Context context) {
    if (mHasStarted) {
      return;
    }
    mHasStarted = true;
    mSensorManager = (SensorManager) context.getApplicationContext().getSystemService(Context.SENSOR_SERVICE);
    Sensor lightSensor = mSensorManager.getDefaultSensor(Sensor.TYPE_LIGHT); // 获取光线传感器
    if (lightSensor != null) { // 光线传感器存在时
      mLightSensorListener = new LightSensorListener();
      mSensorManager.registerListener(mLightSensorListener, lightSensor, SensorManager.SENSOR_DELAY_NORMAL); // 注册事件监听
    }
  }
  public void stop() {
    if (!mHasStarted || mSensorManager == null) {
      return;
    }
    mHasStarted = false;
    mSensorManager.unregisterListener(mLightSensorListener);
  }
  /**
   * 获取光线强度
   */
  public float getLux() {
    if (mLightSensorListener != null) {
      return mLightSensorListener.lux;
    }
    return -1.0f; // 默认返回-1，表示设备无光线传感器或者为调用start()方法
  }
  private class LightSensorListener implements SensorEventListener {
    private float lux; // 光线强度
    public void onAccuracyChanged(Sensor sensor, int accuracy) {
    }
    public void onSensorChanged(SensorEvent event) {
      if (event.sensor.getType() == Sensor.TYPE_LIGHT) {
        // 获取光线强度
        lux = event.values[0];
        if (DEBUG) {
          Log.d(TAG, "lux : " + lux);
        }
      }
    }
  }
}