/// <summary>
 /// 获取某用户的所有第三方账号绑定
 /// </summary>
 /// <param name="userId"></param>
 /// <returns>若没有,则返回空集合</returns>
 public IEnumerable <AccountBinding> GetAccountBindings(long userId)
 {
     return(accountBindingRepository.GetAccountBindings(userId));
 }