android 设置屏幕亮度

protected void setBrightness() {

WindowManager.LayoutParams lp = ((Activity) mContext).getWindow().getAttributes();
int brightness =  Settings.System.getInt(mContext.getContentResolver(),
Settings.System.SCREEN_BRIGHTNESS,0);
//		if(brightness <217)
//			lp.screenBrightness = 0.85f;
//		else
//		brightness += 10;
//		if(brightness > 255)
//			brightness = 60;

lp.screenBrightness = brightness/255.0f;
((Activity) mContext).getWindow().setAttributes(lp);

Settings.System.putInt(mContext.getContentResolver(), Settings.System.SCREEN_BRIGHTNESS, brightness);
}