session实现购物车原理讲解（使用Session和cookie会话对象实现简单购物车功能（超详细））

一
  
  
  
  
  
  
 、新建项目 
  
  
  
  
  
 、实体类 


 


 


 


 


 


 
、servlet

1.新建Dynamic Web project
  
  
  
  
  
  
 ，新建过程如下；

2.在src目录下新建两个包 
  
  
  
  
  
 ，一个命名为entity 


 


 


 


 


 


 
，一个命名为servlet
 
 
 
 
 
 
，新建过程如下；

3.在entity目录下新建两个实体类  
   
   
   
   
   
  ，一个名为Cake,一个名为CakeDB,新建过程如下：

4.在servlet目录下新建三个servlet 

 

 

 

 

 

 
，命名分别为ListCakeServlet
 
 
 
 
 
 
、PurchaseServlet和CartServlet

 

 

 

 

 

 
，新建过程如下：

所有东西建完后结果如图：

二：源代码

1.Cake实体类：

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

2.CakeDB实体类：

package entity; 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 {//模拟数据库中的记录 cake.put("1001", new Cake("1001", "A类：巧克力蛋糕")); cake.put("1002", new Cake("1002", "B类：水果沙拉蛋糕")); cake.put("1003", new Cake("1003", "C类：慕斯蛋糕")); cake.put("1004", new Cake("1004", "D类：奶油蛋糕")); cake.put("1005", new Cake("1005", "E类：干果蛋糕")); } // 获得所有的蛋糕 public static Collection<Cake> getAll() { return cake.values(); } // 根据指定的id获蛋糕 public static Cake getCake(String id) { return cake.get(id); } }

3.ListCakeServlet：

package servlet; import java.io.IOException; import java.io.PrintWriter; import java.util.Collection; 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 entity.Cake; import entity.CakeDB; @WebServlet("/ListCakeServlet") public class ListCakeServlet extends HttpServlet { private static final long serialVersionUID = 1L; public ListCakeServlet() { super(); } protected void doGet(HttpServletRequest request, HttpServletResponse resp) throws ServletException, IOException { resp.setContentType("text/html;charset=utf-8"); PrintWriter out = resp.getWriter(); Collection<Cake> cakes = CakeDB.getAll(); out.write("本站提供的蛋糕有：<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 doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }

4.PurchaseServlet：

package servlet; import java.io.IOException; import java.util.ArrayList; import java.util.List; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.Cookie; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; import entity.Cake; import entity.CakeDB; @WebServlet("/PurchaseServlet") public class PurchaseServlet extends HttpServlet { private static final long serialVersionUID = 1L; public PurchaseServlet() { super(); } protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { // 获得用户购买的商品 String id = req.getParameter("id"); if (id == null) { // 如果id为null             ，重定向到ListBookServlet页面 String url = "ListBookServlet"; resp.sendRedirect(url); return; } Cake book = CakeDB.getCake(id); // 创建或者获得用户的Session对象 HttpSession session = req.getSession(); // 从Session对象中获得用户的购物车 List<Cake> cart = (List) session.getAttribute("cart"); if (cart == null) { // 首次购买 
 

 
 

 
 

 
 

 
 

 
 

 
，为用户创建一个购物车(List集合模拟购物车) cart = new ArrayList<Cake>(); // 将购物城存入Session对象 session.setAttribute("cart", cart); } // 将商品放入购物车 cart.add(book); // 创建Cookie存放Session的标识号 Cookie cookie = new Cookie("JSESSIONID", session.getId()); cookie.setMaxAge(60 * 30); cookie.setPath("/Servlet"); resp.addCookie(cookie); // 重定向到购物车页面 String url = "CartServlet"; resp.sendRedirect(url); } protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }

5.CartServlet:

package servlet; import entity.Cake; 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("/CartServlet") public class CartServlet extends HttpServlet { protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException{ resp.setContentType("text/html;charset=utf-8"); PrintWriter out = resp.getWriter(); List<Cake> cart = null; boolean purFlag = true; HttpSession session = req.getSession(false); if (session == null) { purFlag =false; } else { cart = (List) session.getAttribute("cart"); if (cart == null){ purFlag=false; } } if(!purFlag){ out.write("抱歉












，您还没有购买任何商品！<br>"); } else { out.write("您购买的蛋糕有：<br>"); double price = 0; for (Cake cake:cart){ out.write(cake.getName() +"<br>"); } } } }

三  
   
   
   
   
   
  、运行

1.在ListCakeServlet文件下运行                   ，点击鼠标右键 
 
 
 
 
 
 
 
 
 
 
 
 
，选择run as


















，具体如图:

2.运行结果如图：

点击购买之后跳转CartServlet页面             ，比如我点了巧克力蛋糕后：

以上就是使用Session和cookie会话对象实现简单购物车功能            。希望对你有帮助哦~