源码：

　　base\services\core\java\com\android\server\lights\LightsService.java

功能：

　　主要对JNI再封装了一层

　　对上：构造了setBrightness接口函数供调用

　　对下：调用JNI对应方法

源码分析：

LightsService构造函数：

　　调用JNI的init方法

public LightsService(Context context) {    super(context);    // 调用jni方法    mNativePointer = init_native();    for (int i = 0; i < LightsManager.LIGHT_ID_COUNT; i++) {        mLights[i] = new LightImpl(i);    }}

setBrightness：

　　调用JNI的setLight方法进行背光调节

public void setBrightness(int brightness)    setBrightness(brightness, BRIGHTNESS_MODE_USER);        setLightLocked(color, LIGHT_FLASH_NONE, 0, 0, brightnessMode);            setLight_native(mNativePointer, mId, color, mode, onMS, offMS, brightnessMode);    // JNI