Android调节屏幕亮度实现代码

调节屏幕亮度时，先设置当前activity亮度，再并保存为系统亮度即可。

1 oncreate()里检查系统亮度并设置seekbar：

     private void screenbrightness_check()
     {
          //先关闭系统的亮度自动调节
          try
          {
              if(android.provider.settings.system.getint(getcontentresolver(),android.provider.settings.system.screen_brightness_mode) == android.provider.settings.system.screen_brightness_mode_automatic)
              {    
                   android.provider.settings.system.putint(getcontentresolver(),
                        android.provider.settings.system.screen_brightness_mode,
                        android.provider.settings.system.screen_brightness_mode_manual);
              }
          }
          catch (settingnotfoundexception e)
          {
              // todo auto-generated catch block
              e.printstacktrace();
          }
          //获取当前亮度,获取失败则返回255
          intscreenbrightness=(int)(android.provider.settings.system.getint(getcontentresolver(),
                   android.provider.settings.system.screen_brightness,
                   255));
          //文本、进度条显示
          mseekbar_light.setprogress(intscreenbrightness);
          mtextview_light.settext(""+intscreenbrightness*100/255);
         
     }

2 拖动seekbar时设置当前activity亮度，并保存为系统亮度：
        

//屏幕亮度
     private void setscreenbritness(int brightness)
     {
          //不让屏幕全暗
          if(brightness<=1)
          {
              brightness=1;
          }
          //设置当前activity的屏幕亮度
          windowmanager.layoutparams lp = this.getwindow().getattributes();
          //0到1,调整亮度暗到全亮
          lp.screenbrightness = float.valueof(brightness/255f); 
          this.getwindow().setattributes(lp);
    
          //保存为系统亮度方法1
          android.provider.settings.system.putint(getcontentresolver(),
                   android.provider.settings.system.screen_brightness,
                   brightness);
         
          //保存为系统亮度方法2
//        uri uri = android.provider.settings.system.geturifor("screen_brightness"); 
//        android.provider.settings.system.putint(getcontentresolver(), "screen_brightness", brightness);  
//        // resolver.registercontentobserver(uri, true, mycontentobserver); 
//        getcontentresolver().notifychange(uri, null);
         
          //更改亮度文本显示
          mtextview_light.settext(""+brightness*100/255);
     }