通过session模拟蛋糕购物车

迷南。 2023-10-03 21:07 17阅读 0赞

1，创建封装蛋糕信息的类，cake类

public class Cake {
        
        private String id;
        private String name;
    
        public Cake(String id, String name) {
        
            this.id = id;
            this.name = name;
        }
    
        public String getId() {
        
            return id;
        }
    
        public void setId(String id) {
        
            this.id = id;
        }
    
        public String getName() {
        
            return name;
        }
    
        public void setName(String name) {
        
            this.name = name;
        }
    }

2，创建数据库模拟类cakedb类

import java.util.Collection;
    import java.util.LinkedHashMap;
    import java.util.Map;
    
    public class CakeDB {
        
        private static Map<String,Cake> cake=new LinkedHashMap<String, Cake>();
        static {
        
            cake.put("1   ",new Cake("1","A类蛋糕"));
            cake.put("2",new Cake("2","B类蛋糕"));
            cake.put("3",new Cake("3","C类蛋糕"));
            cake.put("4",new Cake("4","D类蛋糕"));
            cake.put("5",new Cake("5","E类蛋糕"));
        }
        public static Collection<Cake>getAll(){
        
            return cake.values();
        }
        public static Cake getCake(String id){
        
            return cake.get(id);
        }
    }

3，创建一个名为ListCakeServlet的类，该servlet用于显示所有可购买蛋糕的列表，通过点击购买的超链接，便可将蛋糕添加到购物车中。

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.io.PrintWriter;
    import java.util.Collection;
    
    @WebServlet(name = "ListCakeServlet",urlPatterns = "/ListCakeServlet")
    public class ListCakeServlet extends HttpServlet {
        
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        
            response.setContentType("text/html;charset=utf-8");
            PrintWriter out=response.getWriter();
            Collection<Cake> cakes=CakeDB.getAll();
            out.write("本网站提供的蛋糕有<br>");
            for (Cake cake:cakes){
        
                String url="PurchaseServlet?id="+cake.getId();
                out.write(cake.getName()+"<a href='"+url+"'>点击购买</a><br>");
            }
        }
    
        protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        
            this.doPost(request,response);
        }
    }

4，创建名为PurchaseServlet的类

import javax.servlet.ServletException;
    import javax.servlet.annotation.WebServlet;
    import javax.servlet.http.*;
    import java.io.IOException;
    import java.util.ArrayList;
    import java.util.List;
    
    @WebServlet(name = "PurchaseServlet",urlPatterns = "/PurchaseServlet")
    public class PurchaseServlet extends HttpServlet {
        
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        
            String id=request.getParameter("id");
            if (id==null){
        
                String url="ListCakeServlet";
                response.sendRedirect(url);
                return;
            }
            Cake cake=CakeDB.getCake(id);
            HttpSession session=request.getSession();
            List<Cake> cart=(List)session.getAttribute("cart");
            if (cart==null){
        
                cart=new ArrayList<Cake>();
                session.setAttribute("cart",cart);
            }
            cart.add(cake);
            Cookie cookie=new Cookie("JSESSIONID",session.getId());
            cookie.setMaxAge(60*30);
            cookie.setPath("/Servlet");
            response.addCookie(cookie);
            String url="CartServlet";
            response.sendRedirect(url);
        }
    
        protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        
            this.doPost(request,response);
        }
    }

5，创建一个CartServlet的servlet类，该类主要用于展示用户已经购买的蛋糕列表

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 javax.servlet.http.HttpSession;
    import java.io.IOException;
    import java.io.PrintWriter;
    import java.util.List;
    
    @WebServlet(name = "CartServlet",urlPatterns = "/CartServlet")
    public class CartServlet extends HttpServlet {
        
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        
            response.setContentType("text/html;charset=utf-8");
            PrintWriter out=response.getWriter();
            List<Cake> cart=null;
            boolean pruFlag=true;
            HttpSession session=request.getSession(false);
            if (session==null){
        
                pruFlag=false;
            }else {
        
                cart =(List)session.getAttribute("cart");
                if (cart==null){
        
                    pruFlag=false;
                }
            }
            if (!pruFlag){
        
                out.write("对不起！您还没有购买任何产品");
            }
            else {
        
                out.write("您购买的蛋糕有：<br>");
                double price=0;
                for (Cake cake:cart){
        
                    out.write(cake.getName()+"<br>");
                }
            }
        }
    
        protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        
            this.doPost(request,response);
        }
    }