Android按键灯流程分析

调用代码为：alpsframeworksaseservicesjavacomAndroidserverLightsService.java使用方法：
private LightsService.Light mButtonLight;
mButtonLight = mLightsService.getLight（LightsService.LIGHT_ID_BUTTONS）;
mButtonLight.setBrightness（screenBrightness）;
mButtonLight.turnOff（）;本地代码在：
alpsframeworksaseservicesjnicom_android_server_LightsService.cpp接口关联使用：
static JNINativeMethod method_table[] = {
{ "init_native", "（）I", （void*）init_native },
{ "finalize_native", "（I）V", （void*）finalize_native },
{ "setLight_native", "（IIIIIII）V", （void*）setLight_native },
};int register_android_server_LightsService（JNIEnv *env）
{
return jniRegisterNativeMethods（env, "com/android/server/LightsService",
method_table, NELEM（method_table））;
}register_android_server_LightsService函数在alpsframeworksaseservicesjnionload.cpp里面注册本地c代码在：
alpsmediatekhardwareliblightslights.c里面open_lights里面static int
set_light_buttons（struct light_device_t* dev,
struct light_state_t const* state）
{
int err = 0;
int on = is_lit（state）;
pthread_mutex_lock（&g_lock）;
g_buttons = on;
err = write_int（BUTTON_FILE, on？255:0）;
pthread_mutex_unlock（&g_lock）;
return err;
}com_android_server_LightsService.cp里面使用 devices->lights[light]->set_light（devices->lights[light], &state）;来调用真正的代码
如果有root机子，可以如下测试：
echo 0 > /sys/class/leds/button-backlight/brightness 关按键灯
echo 1 > /sys/class/leds/button-backlight/brightness 开按键灯

echo 0 > /sys/class/leds/button-backlight/brightness 执行的意思为：输出0，作为/sys/class/leds/button-backlight/brightness的输入传入。
如此便会打开brightness设备，并执行write将0带入执行。相关阅读：按键从Linux到Android http://www.linuxidc.com/Linux/2013-10/91994.htmAndroid 4.0中按键的处理流程 http://www.linuxidc.com/Linux/2013-02/79402.htmAndroid 中如何监听按键的长按事件 http://www.linuxidc.com/Linux/2012-12/76572.htmAndroid输入法框架中按键消息的处理流程 http://www.linuxidc.com/Linux/2012-11/74423.htm更多Android相关信息见Android 专题页面 http://www.linuxidc.com/topicnews.aspx？tid=11