由于修改系統(tǒng) Settings 中的屏幕亮度，由于會(huì)影響到所有APP，需要申請(qǐng)修改Settings的權(quán)限<uses-permission * android:name="android.permission.WRITE_SETTINGS"/>，同時(shí)需要取消光感自動(dòng)調(diào)節(jié)屏幕亮度的功能，設(shè)置為手動(dòng)調(diào)節(jié)模式，否則光感傳感器會(huì)隨著光照強(qiáng)度的變化修改系統(tǒng)屏幕亮度，并且非系統(tǒng)簽名的APP，需要用戶手動(dòng)授權(quán)后才可以修改背光亮度。

以下就是系統(tǒng)亮度的實(shí)現(xiàn)方式：
1、效果圖

       <SeekBar
            android:id="@+id/car_brightness"
            android:layout_width="496px"
            android:layout_height="80px"
            android:max="100"
            android:progress="0"
             />

        <ImageView
            android:layout_width="40px"
            android:layout_height="41px"
            android:layout_marginStart="385px"
            android:layout_marginTop="19px"
            android:src="@mipmap/icon_brightness" />

3、工具類(lèi)

/**
 * 屏幕亮度工具類(lèi)
 */
public class BrightnessUtil {

    /**
     *獲取系統(tǒng)屏幕亮度
     */
    public static int getBrightness(Context context) {
        int brightness = -1;
        ContentResolver resolver = context.getContentResolver();
        try {
            brightness = Settings.System.getInt(resolver, Settings.System.SCREEN_BRIGHTNESS);
        } catch (Settings.SettingNotFoundException e) {
            e.printStackTrace();
        }
        Log.e("ccm=======>","getBrightness: "+brightness);
        return brightness;
    }

    /**
     *獲取系統(tǒng)最大屏幕亮度
     */
    public static int getMaxBrightness(Context context) {
        int brightnessSettingMaximumId = context.getResources().getIdentifier("config_screenBrightnessSettingMaximum", "integer", "android");
        int brightnessSettingMaximum = context.getResources().getInteger(brightnessSettingMaximumId);
        Log.e("ccm=======>","getMaxBrightness: "+brightnessSettingMaximum);
        return brightnessSettingMaximum;
    }

    /**
     *調(diào)節(jié)當(dāng)前屏幕亮度
     */
    public static void SetSystemLight(int lightnumber, Activity activity){
        Window window = activity.getWindow();//對(duì)當(dāng)前窗口進(jìn)行設(shè)置
        WindowManager.LayoutParams layoutparams = window.getAttributes();//獲取窗口屬性為后面亮度做鋪墊作用
        layoutparams.screenBrightness =lightnumber / 255.0f;//用窗口管理（自定義的）layoutparams獲取亮度值，android亮度值處于在0-255之間的整形數(shù)值
        window.setAttributes(layoutparams);//設(shè)置當(dāng)前窗口屏幕亮度
    }

    /**
     * 5.修改Setting 中屏幕亮度值
     *
     * 修改Setting的值需要?jiǎng)討B(tài)申請(qǐng)權(quán)限 <uses-permission
     * android:name="android.permission.WRITE_SETTINGS"/>
     * **/
    public static void ModifySettingsScreenBrightness(Context context, int birghtessValue) {
        // 首先需要設(shè)置為手動(dòng)調(diào)節(jié)屏幕亮度模式
        setScreenManualMode(context);

        ContentResolver contentResolver = context.getContentResolver();
        Log.e("ccm=======>", "birghtessValue: "+birghtessValue);
        Settings.System.putInt(contentResolver,
                Settings.System.SCREEN_BRIGHTNESS, birghtessValue);
    }


    /**
     * 3.關(guān)閉光感，設(shè)置手動(dòng)調(diào)節(jié)背光模式
     *
     * SCREEN_BRIGHTNESS_MODE_AUTOMATIC 自動(dòng)調(diào)節(jié)屏幕亮度模式值為1
     *
     * SCREEN_BRIGHTNESS_MODE_MANUAL 手動(dòng)調(diào)節(jié)屏幕亮度模式值為0
     * **/
    public static void setScreenManualMode(Context context) {
        ContentResolver contentResolver = context.getContentResolver();
        try {
            int mode = Settings.System.getInt(contentResolver,
                    Settings.System.SCREEN_BRIGHTNESS_MODE);
            if (mode == Settings.System.SCREEN_BRIGHTNESS_MODE_AUTOMATIC) {
                Settings.System.putInt(contentResolver,
                        Settings.System.SCREEN_BRIGHTNESS_MODE,
                        Settings.System.SCREEN_BRIGHTNESS_MODE_MANUAL);
            }
        } catch (Settings.SettingNotFoundException e) {
            e.printStackTrace();
        }
    }

}

4、實(shí)現(xiàn)類(lèi)

 private void initBrightness(){
        if (!Settings.System.canWrite(QuickCircularActivity.this)) {
            Intent intent = new Intent(Settings.ACTION_MANAGE_WRITE_SETTINGS, Uri.parse("package:" + getPackageName()));
            startActivityForResult(intent, REQUEST_CODE_WRITE_SETTINGS);
        }
        //將系統(tǒng)最大屏幕亮度值設(shè)為seekbar的最大進(jìn)度值
        mCarBrightness.setMax(BrightnessUtil.getMaxBrightness(QuickCircularActivity.this));
        //將系統(tǒng)當(dāng)前屏幕亮度值設(shè)為seekbar當(dāng)前進(jìn)度值
        Log.e("ccm=======>", "setOneProgress: " + BrightnessUtil.getBrightness(QuickCircularActivity.this));
        int brightness = BrightnessUtil.getBrightness(QuickCircularActivity.this);
        mCarBrightness.setProgress(brightness);
        mCarBrightness.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {
            @Override
            public void onProgressChanged(SeekBar seekBar, int progress, boolean b) {
                Log.e("ccm=======>", "onProgressChanged: " + progress);
                ModifySettingsScreenBrightness(QuickCircularActivity.this,progress);
            }

            @Override
            public void onStartTrackingTouch(SeekBar seekBar) {

            }

            @Override
            public void onStopTrackingTouch(SeekBar seekBar) {

            }
        });

    }