android调节屏幕亮度

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首先要知道当前设备是否处于自动调节的状态：

public static boolean isAutoBrightness(ContentResolver aContentResolver) {            boolean automicBrightness = false;            try{                automicBrightness = Settings.System.getInt(aContentResolver,                        Settings.System.SCREEN_BRIGHTNESS_MODE) == Settings.System.SCREEN_BRIGHTNESS_MODE_AUTOMATIC;            }         catch(SettingNotFoundException e)         {                e.printStackTrace();            }            return automicBrightness;      }

随后，需要获取当前屏幕亮度，用于绑定给自定义的seekbar：

    public static int getScreenBrightness(Activity activity) {           int nowBrightnessValue = 0;            ContentResolver resolver = activity.getContentResolver();            try{                nowBrightnessValue = android.provider.Settings.System.getInt(resolver, Settings.System.SCREEN_BRIGHTNESS);            }         catch(Exception e) {                e.printStackTrace();            }            return nowBrightnessValue;      }

紧接着，就需要设置屏幕亮度：

public static void setBrightness(Activity activity, int brightness) {         WindowManager.LayoutParams lp = activity.getWindow().getAttributes();            lp.screenBrightness = Float.valueOf(brightness) * (1f / 255f);    <span style="white-space:pre"></span>   activity.getWindow().setAttributes(lp);        }

有的时候设置了并没有生效，那是因为没有关闭自动调节功能,下面的方法能够对自动调节进行关闭：

  public static void stopAutoBrightness(Activity activity) {            Settings.System.putInt(activity.getContentResolver(),                    Settings.System.SCREEN_BRIGHTNESS_MODE,                    Settings.System.SCREEN_BRIGHTNESS_MODE_MANUAL);       }                       //最后一个参数设置为  <span style="font-family: Consolas, 'Courier New', Courier, mono, serif; line-height: 18px;">Settings.System.SCREEN_BRIGHTNESS_MODE_AUTOMATIC的时候是开启自动调节。</span>

当然，设置了之后还需要对设置的值进行保存：

   public static void saveBrightness(ContentResolver resolver, int brightness) {            Uri uri = android.provider.Settings.System.getUriFor("screen_brightness");            android.provider.Settings.System.putInt(resolver, "screen_brightness", brightness);            // resolver.registerContentObserver(uri, true, myContentObserver);            resolver.notifyChange(uri, null);}

如果要用seekbar实现那就自定义一个seekbar的监听器

class myOnSeekBarChangeListener implements OnSeekBarChangeListener{@Override    public void onStopTrackingTouch(SeekBar seekBar) { int tmpInt = seekBar.getProgress();                    // 当进度小于80时，设置成80，防止太黑看不见的后果。                  if (tmpInt < 80) {                      tmpInt = 80;                  }                    // 根据当前进度改变亮度                  Settings.System.putInt(getActivity().getContentResolver(),                          Settings.System.SCREEN_BRIGHTNESS, tmpInt);                  tmpInt = Settings.System.getInt(getActivity().getContentResolver(),                          Settings.System.SCREEN_BRIGHTNESS, -1);                  WindowManager.LayoutParams wl = getActivity().getWindow().getAttributes();                    float tmpFloat = (float) tmpInt / 255;                  if (tmpFloat > 0 && tmpFloat <= 1) {                      wl.screenBrightness = tmpFloat;                  }                  getActivity().getWindow().setAttributes(wl);      }        @Override    public void onStartTrackingTouch(SeekBar seekBar) {    // TODO Auto-generated method stub        }        @Override    public void onProgressChanged(SeekBar seekBar, int progress,    boolean fromUser) {        }}

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