HarmonyOS 使用resourceManager 去获取颜色的string， 提示Resource not found by id

ResourceUtils.getStringSync($r("app.color.color_bg_ff000000"))

export function getStringSync(res: Resource): string | undefined {
  try {
    let mgr: resourceManager.ResourceManager | undefined =
      GlobalData.mainContext?.createModuleContext(res.moduleName)?.resourceManager;
    if (mgr) {
      return mgr.getStringSync(res);
    } else {
      Log.w(TAG, `getResourceManager instance is none`);
      return undefined;
    }
  } catch (error) {
    Log.e(TAG, `getResourceString error: ${error}`);
    return undefined;
  }
}