javaweb学习——session和Cookie实现购物车功能-白红宇

javaweb学习——session和Cookie实现购物车功能

阅读量：4977 次

发布时间：2019-06-12

本文共 7196 字，大约阅读时间需要 23 分钟。

1.创建Book类，实现对图书信息的封装。

package cn.it.sessionDemo.example1;import java.io.Serializable;/** * 该类实现对图书的封装 *  * @author 12428 * */public class Book implements Serializable {    private static final long serialVersionUID = 1L;    private String ID;    private String name;    public Book() {    }    public Book(String ID, String name) {        this.ID = ID;        this.name = name;    }    public String getID() {        return ID;    }    public void setID(String iD) {        ID = iD;    }    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }}

2.创建一个BookDB类实现对图书类的操作

package cn.it.sessionDemo.example1;import java.util.Collection;import java.util.LinkedHashMap;import java.util.Map;/** * 该类实现数据库模拟 *  * @author 12428 * */public class BookDB {    private static Map
     
       books = new LinkedHashMap
      
       ();    // 静态代码块在Java类被加载时执行，由于类只加载一次，应此静态代码块只执行一次。    static {        books.put("1", new Book("1", "javaweb开发"));        books.put("2", new Book("2", "jdbc开发"));        books.put("3", new Book("3", "java基础"));        books.put("4", new Book("4", "struts开发"));        books.put("5", new Book("5", "spring开发"));    }    // 获得所有的图书    public static Collection
       
         getAll() {        return books.values();    }    // 根据指定的ID获得图书    public static Book getBook(String ID) {        return books.get(ID);    }}

3.创建一个ListBookServlet类，用来显示可购买的图书信息。

package cn.it.sessionDemo.example1;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;/** * 该servlet是显示所有的图书列表。通过图书后面的购买连接可以把图书添加到购物车中 *  * @author 12428 * */@WebServlet("/ListBookServlet")public class ListBookServlet extends HttpServlet {    private static final long serialVersionUID = 1L;    public ListBookServlet() {        super();        // TODO Auto-generated constructor stub    }    protected void doGet(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        response.setContentType("text/html;charset=utf-8");        PrintWriter out = response.getWriter();        Collection
     
       books = BookDB.getAll();        out.write("本站的图书有：");        for (Book b : books) {            // 将图书的id值作为参数传过去            String url = "/SessionDemo2/PurchaseServlet?id=" + b.getID();            out.write(b.getName() + "
      点击购买
      
");        }    }    protected void doPost(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        // TODO Auto-generated method stub        doGet(request, response);    }}

4.创建一个实现购物车功能的servlet类

package cn.it.sessionDemo.example1;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;/** * 该servlet类是用于实现购物车功能，既将用户购买的东西作为session的属性值存进去，再重定向到 到已购买商品的也买你 *  * @author 12428 * */@WebServlet("/PurchaseServlet")public class PurchaseServlet extends HttpServlet {    private static final long serialVersionUID = 1L;    public PurchaseServlet() {        super();        // TODO Auto-generated constructor stub    }    protected void doGet(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        // 获得用户的购买信息        String id = request.getParameter("id");        // 有些用户会直接访问这个Servlet，先判断访问时是否带有书的ID        if (id == null) {            // 如果Id为空，返回图书列表Servlet            String url = "/SessionDemo2/ListBookServlet";            response.sendRedirect(url);  //此处一定要返回，不然会出现错误            return;        }        // 获取购买的图书信息        Book book = BookDB.getBook(id);        // 创建session对象        HttpSession session = request.getSession();        // 从session中获得购物车对象        List
     
       cart = (List
      
       ) session.getAttribute("cart");        // 判断session对象是否有cart这个属性,如果没有这个属性的话，集合cart的值应为空        if (cart == null) {            // 没有cart属性，用户是首次购买，为用户创建一个购物车            cart = new ArrayList
       
        ();            // 将购物车对象添加到session对象中            session.setAttribute("cart", cart);        }        // 将商品放入购物车        cart.add(book);        // 创建一个Cookie存放session的信息        Cookie cookie = new Cookie("JSESSION", session.getId());        cookie.setMaxAge(60 * 30);        cookie.setPath("/SessionDemo2");        // 将cookie发送到客户端        response.addCookie(cookie);        // 重定向到已购买商品的页面。        String url = "/SessionDemo2/CartServlet";        response.sendRedirect(url);    }    /**     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse     *      response)     */    protected void doPost(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        // TODO Auto-generated method stub        doGet(request, response);    }}

5.创建一个展示用户购买信息的类

package cn.it.sessionDemo.example1;import java.io.IOException;import java.io.PrintWriter;import java.util.List;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;@WebServlet("/CartServlet")public class CartServlet extends HttpServlet {    private static final long serialVersionUID = 1L;    public CartServlet() {        super();        // TODO Auto-generated constructor stub    }    protected void doGet(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        response.setContentType("text/html;charset=utf-8");        PrintWriter out = response.getWriter();        // 变量cart引用用户的购物车        List
     
       cart = null;        // 创建一个变量是来判断用户是否购买过商品        boolean Flag = true;        // 获得用户的session,如果没有查到也不创建新的session。        HttpSession session = request.getSession(false);        // 如果session为空，Flag为false；        if (session == null) {            Flag = false;        } else {
   // 不为空，就获得用户的购物车            cart = (List
      
       ) session.getAttribute("cart");            // 如果用户的购物车为空，就设置Falg为false。            if (cart == null) {                Flag = false;            }        }        // 如果Flag为false，表明用户没有购买过商品，重定向到ListServlet页面。        if (!Flag) {            out.write("对不起，你没有购买任何商品");        } else {            // 显示用户的购买信息            out.write("你购买的商品有：");            for (Book b : cart) {                out.write(b.getName() + "
       
");            }        }    }    protected void doPost(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        // TODO Auto-generated method stub        doGet(request, response);    }}