computer-web/src/main/java/example/controller/CartServlet.java

package example.controller;

import example.model.Computer;
import example.model.User;
import example.service.ICartService;
import example.service.impl.CartServiceImpl;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.List;

@WebServlet("/cart")
public class CartServlet extends HttpServlet {

    ICartService cartService = new CartServiceImpl();

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        String action = req.getParameter("action");
        switch (action){
            case "list":
                try {
                    toCart(req, resp);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                }
                break;
            case "add":
                try {
                    addCart(req,resp);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                }
                break;
            case "remove":
                try {
                    removeFromCart(req, resp);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                }
                break;
            default:
                req.getRequestDispatcher("/WEB-INF/jsp/cart.jsp").forward(req,resp);
                break;
        }
    }

    private void removeFromCart(HttpServletRequest req, HttpServletResponse resp) throws Exception {
        User user = (User) req.getSession().getAttribute("user");
        String id = req.getParameter("id");
        cartService.removeFromCart(Integer.parseInt(id),user.getId());
        try {
            toCart(req, resp);
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }

    private void addCart(HttpServletRequest req, HttpServletResponse resp) throws Exception {
        String id = req.getParameter("id");
        User user = (User) req.getSession().getAttribute("user");
        cartService.addCart(Integer.parseInt(id),user.getId());
        req.setAttribute("msg","加购成功");
        req.getRequestDispatcher("/computerList").forward(req,resp);
    }

    private void toCart(HttpServletRequest req, HttpServletResponse resp) throws Exception {
        User user = (User) req.getSession().getAttribute("user");
        List<Computer> computers = cartService.myCart(user.getId());
        req.setAttribute("computers",computers);
        req.getRequestDispatcher("cart.jsp").forward(req,resp);
    }
}