/// <summary>
        /// 添加到购物车
        /// </summary>
        /// <param name="id"></param>
        /// <param name="returnUrl"></param>
        /// <returns></returns>
        public RedirectToRouteResult AddToCart(int id, string returnUrl)
        {
            var book = _bookRepository.Books.FirstOrDefault(x => x.Id == id);

            if (book != null)
            {
                GetCart().AddBook(book, 1);
            }

            return RedirectToAction("Index", new { returnUrl });
        }

MVC 跳转 RedirectToRouteResult