关于设置屏幕常亮问题

import { BusinessError } from '@ohos.base'; 
import { window } from '@kit.ArkUI'; 
import common from '@ohos.app.ability.common'; 
@Entry 
@Component 
struct WebPage { 
  private context = getContext(this) as common.UIAbilityContext; 
  controller: webView.WebviewController = new webView.WebviewController(); 
  build() { 
    Column() { 
      Button('keeplight') 
        .onClick(() => { 
          // 1.获取应用主窗口。 
          let windowClass: window.Window | undefined = undefined; 
          try { 
            window.getLastWindow(this.context, (err: BusinessError, data) => { 
              const errCode: number = err.code; 
              if (errCode) { 
                console.error('Failed to obtain the top window. Cause: ' + JSON.stringify(err)); 
                return; 
              } 
              windowClass = data; 
              console.info('Succeeded in obtaining the top window. Data: ' + JSON.stringify(data)); 
              try { 
                windowClass.setWindowKeepScreenOn(true, (err: BusinessError) => { 
                  const errCode: number = err.code; 
                  if (errCode) { 
                    console.error('Failed to set the screen to be always on. Cause: ' + JSON.stringify(err)); 
                    return; 
                  } 
                  console.info('Succeeded in setting the screen to be always on.'); 
                }); 
              } catch (exception) { 
                console.error('Failed to set the screen to be always on. Cause: ' + JSON.stringify(exception)); 
              } 
            }); 
          } catch (exception) { 
            console.error('Failed to obtain the top window. Cause: ' + JSON.stringify(exception)); 
          } 
        }) 
    } 
  } 
}

05-15 14:48:04.050   12178-12178  A03d00/JSAPP                   com.examp...lication  I     Succeeded in obtaining the top window. Data: {} 
05-15 14:48:04.059   12178-12178  A03d00/JSAPP                   com.examp...lication  I     Succeeded in setting the screen to be always on.