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~