采用MVC模式,完成了对用户的管理(删除用户),对图书的管理(增,删,改,查),订单管理(购买图书,删除图书,修改图书的数量).-Using MVC model, completed the user management (delete user), the management of the books (by adding, changing, checking), order management (purchase of books, book delete, modify the n