使用session技术来实现网上商城购物车的功能

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<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
<%@page import="java.util.*"%>
DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>购物页面title>
head>
<body>
<h1>商品列表h1>
<ul >
    <li><a href="/myday07/addcookie?id=1">java基础a><a href="/myday07/buysession?id=1">购买a>li>
    <li><a href="/myday07/addcookie?id=2">javaweba><a href="/myday07/buysession?id=2">购买a>li>
    <li><a href="/myday07/addcookie?id=3">DHTMLa><a href="/myday07/buysession?id=3">购买a>li>
    <li><a href="/myday07/addcookie?id=4">数据库a><a href="/myday07/buysession?id=4">购买a>li>
    <li><a href="/myday07/addcookie?id=5">Strutsa><a href="/myday07/buysession?id=5">购买a>li>
    <li><a href="/myday07/addcookie?id=6">Springa><a href="/myday07/buysession?id=6">购买a>li>
    <li><a href="/myday07/addcookie?id=7">Hibernatea><a href="/myday07/buysession?id=7">购买a>li>
ul>
<h1>最近访问记录h1><h5><a href="/myday07/clearcookie">清空数据a> h5>
<%
    String[] arr = {"java基础","javaweb","DHTML","数据库","Struts","Spring","Hibernate"};
    // 获得所有cookie
    Cookie[] cookies = request.getCookies();

    // 在cookie中查找商品浏览记录
    String visitlist = null;
    if(cookies!=null){
        for (Cookie cookie : cookies) {
            if (cookie.getName().equals("visitlist")) {
                visitlist = cookie.getValue();
                break;
            }
        }
        
        if(visitlist==null){ // 商品列表不存在
            out.println("");
        }else{
            String[] existIds = visitlist.split(",");
            for(String existId:existIds){
                int id = Integer.parseInt(existId);
                out.println(arr[id-1]+"
"); } } } %> <hr> <h1>购物车列表h1> <% //1.获得购物车列表 Map<String, Integer> cart=(Map<String, Integer>)session.getAttribute("cart"); //2.遍历map输出 if(cart!=null){ Set<String> keys=cart.keySet(); for(String id:keys) { int number=cart.get(id);//每件商品的数量 int idInt=Integer.parseInt(id); String productName=arr[idInt-1]; out.println("商品名称:"+productName+",商品数量:"+number+"
"); } } %> <hr/> body> html>
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2、编写商品浏览记录的servlet页面

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package cn.itcast.cookie;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class addCookie extends HttpServlet {

    // 获得用户当前访问商品,更新到商品浏览记录列表
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        // 自动刷新
        response.setHeader("refresh", "2;url=/myday07/products1.jsp");

        // 1、获得当前用户浏览商品id
        String id = request.getParameter("id");
        // 2、获得用户浏览记录列表
        Cookie[] cookies = request.getCookies();
        // 查找访问记录列表 name:visitlist ----- 1,3,5,6
        String visitlist = null;
        if (cookies != null) { // 存在cookie
            for (Cookie cookie : cookies) {
                if (cookie.getName().equals("visitlist")) {
                    visitlist = cookie.getValue();
                    break;
                }
            }
            if (visitlist == null) {
                // 列表不存在,当前商品第一件商品
                Cookie cookie = new Cookie("visitlist", id);
                cookie.setMaxAge(60 * 60);
                response.addCookie(cookie);
                response.getWriter().println("add success");
            } else {
                // 3、判断当前商品是否已经在列表中
                String[] existIds = visitlist.split(",");
                for (String exsitId : existIds) {
                    if (exsitId.equals(id)) { // id存在在列表中
                        response.getWriter().println("add success");
                        return;
                    }
                }
                // 4、如果当前商品不在列表中,添加到列表
                Cookie cookie = new Cookie("visitlist", visitlist + "," + id);
                cookie.setMaxAge(60 * 60);
                response.addCookie(cookie);
                response.getWriter().println("add success");
            }
        } else {
            // 表示 并没有该站点的任何cookie
            Cookie cookie = new Cookie("visitlist", id);
            cookie.setMaxAge(60 * 60);
            response.addCookie(cookie);
            response.getWriter().println("add success");
        }
    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request, response);
    }

}
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3、编写清除缓存的cookie页面

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package cn.itcast.cookie;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class clearCookie extends HttpServlet
{

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException
    {
        Cookie cookie=new Cookie("visitlist","");
        cookie.setMaxAge(0);
        response.addCookie(cookie);
        response.sendRedirect("/myday07/products1.jsp");
        

    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException
    {
        doGet(request, response);
    }

}
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4、编写商品购买页面

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package cn.itcast.cookie;

import java.io.IOException;
import java.util.HashMap;
import java.util.Map;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

public class BuySession extends HttpServlet
{
    //添加商品到购物车
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException
    {
        //1.获得商品的id
        String id=request.getParameter("id");
        //2.获得购物车cart--从session得到
        HttpSession session=request.getSession();
        Map cart=(Map)session.getAttribute("cart");//如果session中没有购物车呢
        if(cart==null)
        {//原来的session中并不存在购物车
            cart=new HashMap();
        }
        //3.判断商品是否存在购物车中
        if(cart.containsKey(id))
        {
            //4.存在数量+1
            int number=cart.get(id);
            cart.put(id, number+1);
        }else{
            //5.不存在 将商品存入购物车   数量1
            cart.put(id, 1);
        }
        session.setAttribute("cart", cart);
        
        response.sendRedirect("/myday07/products1.jsp");//重定向回去
        
        
    }
    
    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException
    {
        doGet(request, response);
    }

}
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最终效果如下:

使用session技术来实现网上商城购物车的功能_第1张图片


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