HarmonyOS 如何实现屏幕常亮

请参考以下代码，onWindowStageCreate在EntryAbility.ets文件中

onWindowStageCreate(windowStage: window.WindowStage) {
  console.info('onWindowStageCreate');
  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));
  }
}