Android 界面亮度设置

业务上需要调节界面亮度，方便二维码扫描，记录一下。

系统的亮度值默认区间是0-255，调节亮度有以下两种

• 当前界面亮度
• 系统亮度

调节当前界面亮度

退出当前界面时，亮度自动调节模式继续生效。

 /**
     * 设置当前界面亮度值
     *
     * @param activity
     * @param aimBrightness
     */
    public static void setCurrentScreenBrightness(Activity activity, @IntRange(from = 0, to = 255) int aimBrightness) {
        WindowManager.LayoutParams layoutParams = activity.getWindow().getAttributes();
        layoutParams.screenBrightness = Float.valueOf(aimBrightness / 255.0f);
        activity.getWindow().setAttributes(layoutParams);
    }

调节系统亮度

调节系统亮度时需要申请WRITE_SETTINGS权限（ 注意6.0以后的权限申请）

<uses-permission android:name="android.permission.WRITE_SETTINGS"/>

注意：只有为手动调节模式时，才能动态设置系统的亮度，所以需要提前对亮度模式进行操作，再进行亮度调节。

通过Activity中的getContentResolver()方法得到ContentResolver实例，实现对系统的ContentProver的数据访问。
Settings.System.SCREEN_BRIGHTNESS_MODE 获取当前屏幕亮度调节模式，其中

• SCREEN_BRIGHTNESS_MODE_AUTOMATIC = 1 表示自动调节模式
• SCREEN_BRIGHTNESS_MODE_MANUAL = 0 表示手动调节模式

  /**
     * 设置系统亮度
     *
     * @param activity
     * @param aimBrightness
     */
    public static void setSystemBrightness(Activity activity, @IntRange(from = 0, to = 255) int aimBrightness) {
        setToManualBrightness(activity);
        Uri uri = Settings.System.getUriFor(Settings.System.SCREEN_BRIGHTNESS);
        ContentResolver resolver = activity.getContentResolver();
        Settings.System.putInt(resolver, Settings.System.SCREEN_BRIGHTNESS, aimBrightness);
        activity.getContentResolver().notifyChange(uri, null);
    }

    /**
     * 设置为手动模式
     *
     * @return
     */
    public static void setToManualBrightness(@NonNull Context context) {
        ContentResolver resolver = context.getContentResolver();
        try {
            int brightMode = Settings.System.getInt(resolver, Settings.System.SCREEN_BRIGHTNESS_MODE);
            if (brightMode == Settings.System.SCREEN_BRIGHTNESS_MODE_AUTOMATIC) {
                //设置为手动调节模式
                Settings.System.putInt(resolver, Settings.System.SCREEN_BRIGHTNESS_MODE,
                        Settings.System.SCREEN_BRIGHTNESS_MODE_MANUAL);
            }
        } catch (Settings.SettingNotFoundException e) {
            e.printStackTrace();
        }
    }

其他

通过 Settings.System.SCREEN_BRIGHTNESS 获取当前屏幕亮度

 /**
     * 获取当前界面亮度值
     *
     * @param context
     * @return
     */
    public static int getCurrentScreenBrightness(@NonNull Context context) {
        ContentResolver resolver = context.getContentResolver();
        int currentBrightness = 0;
        try {
            currentBrightness = Settings.System.getInt(resolver, Settings.System.SCREEN_BRIGHTNESS);
        } catch (Settings.SettingNotFoundException e) {
            e.printStackTrace();
        }
        return currentBrightness;
    }

参考文章