简易购物车Servlet类实现

一 CartServlet实现

package servlet;

import java.io.IOException;

import java.io.PrintWriter;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import dao.ItemsDAO;

import entity.Cart;

import entity.Items;

public class CartServlet extends HttpServlet {

    private String action ; //表示购物车的动作 ,add,show,delete

    //商品业务逻辑类的对象

    private ItemsDAO idao = new ItemsDAO();

    

    

    /**

     * Constructor of the object.

     */

    public CartServlet() {

        super();

    }

    /**

     * Destruction of the servlet. <br>

     */

    public void destroy() {

        super.destroy(); // Just puts "destroy" string in log

        // Put your code here

    }

    /**

     * The doGet method of the servlet. <br>

     *

     * This method is called when a form has its tag value method equals to get.

     *

     * @param request the request send by the client to the server

     * @param response the response send by the server to the client

     * @throws ServletException if an error occurred

     * @throws IOException if an error occurred

     */

    public void doGet(HttpServletRequest request, HttpServletResponse response)

            throws ServletException, IOException {

        doPost(request,response);

    }

    /**

     * The doPost method of the servlet. <br>

     *

     * This method is called when a form has its tag value method equals to post.

     *

     * @param request the request send by the client to the server

     * @param response the response send by the server to the client

     * @throws ServletException if an error occurred

     * @throws IOException if an error occurred

     */

    public void doPost(HttpServletRequest request, HttpServletResponse response)

            throws ServletException, IOException {

        response.setContentType("text/html;charset=utf-8");

        PrintWriter out = response.getWriter();

        if(request.getParameter("action")!=null)

        {

            this.action = request.getParameter("action");

            if(action.equals("add")) //如果是添加商品进购物车

            {

                if(addToCart(request,response))

                {

                    request.getRequestDispatcher("/success.jsp").forward(request, response);

                }

                else

                {

                    request.getRequestDispatcher("/failure.jsp").forward(request, response);

                }

            }

            if(action.equals("show"))//如果是显示购物车

            {

                request.getRequestDispatcher("/cart.jsp").forward(request, response);

            }

            if(action.equals("delete")) //如果是执行删除购物车中的商品

            {

                if(deleteFromCart(request,response))

                {

                    request.getRequestDispatcher("/cart.jsp").forward(request, response);

                }

                else

                {

                    request.getRequestDispatcher("/cart.jsp").forward(request, response);

                }

            }

        }

        

    }

    //添加商品进购物车的方法

    private boolean addToCart(HttpServletRequest request, HttpServletResponse response)

    {

        String id = request.getParameter("id");

        String number = request.getParameter("num");

        Items item = idao.getItemsById(Integer.parseInt(id));

        

        //是否是第一次给购物车添加商品,需要给session中创建一个新的购物车对象

        if(request.getSession().getAttribute("cart")==null)

        {

            Cart cart = new Cart();

            request.getSession().setAttribute("cart",cart);

        }

        Cart cart = (Cart)request.getSession().getAttribute("cart");

        if(cart.addGoodsInCart(item, Integer.parseInt(number)))

        {

            return true;

        }

        else

        {

            return false;

        }

        

    }

    

    //从购物车中删除商品

    private boolean deleteFromCart(HttpServletRequest request, HttpServletResponse response)

    {

        String id = request.getParameter("id");

        Cart cart = (Cart)request.getSession().getAttribute("cart");

        Items item = idao.getItemsById(Integer.parseInt(id));

        if(cart.removeGoodsFromCart(item))

        {

            return true;

        }

        else

        {

            return false;

        }

    }

    

    /**

     * Initialization of the servlet. <br>

     *

     * @throws ServletException if an error occurs

     */

    public void init() throws ServletException {

        // Put your code here

    }

 

}