关于用户浏览商品的历史记录（cookie）

创建对象：用集合模拟数据库：创建一个简单的内容显示界面 <pre name="code" class="java">package com.cn.cookie; import java.io.IOException; import java.io.PrintWriter; import java.util.LinkedHashMap; import java.util.Map; import javax.servlet.ServletException; import javax.servlet.http.Cookie; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; @SuppressWarnings("serial") public class Cookie1 extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //1.创建所有商品信息 response.setCharacterEncoding("UTF-8"); response.setContentType("text/html;charset = UTF-8"); PrintWriter out = response.getWriter(); out.print("<center>"); out.print("所有的商品信息:<br>"); Map<String, Goods> map = Db.getAll(); for(Map.Entry<String, Goods> entry:map.entrySet()){ Goods goods = entry.getValue(); out.print("<a href = '/Userinfo/Cookie2?id="+goods.getId()+"'targent = '_blank'>"+goods.getName()+"</a><br>"); } out.print("</center>"); //2.显示用户曾经浏览过的商品 out.print("你浏览过的商品为：<br>"); Cookie cookies[] = request.getCookies(); for(int i=0;cookies != null && i<cookies.length;i++){ if(cookies[i].getName().equals("goodsHistory")){ String ids[] = cookies[i].getValue().split("\\,"); for(String id :ids){ Goods goods = (Goods) Db.getAll().get(id); out.print("<a href = '/Userinfo/Cookie2?id="+goods.getId()+"'targent = '_blank'>"+goods.getName()+"</a><br/>"); } } } } /** * The doPost method of the servlet. <br> * * This method is called when a form has its tag value method equals to post. * * @param request the request send by the client to the server * @param response the response send by the server to the client * @throws ServletException if an error occurred * @throws IOException if an error occurred */ public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } } class Db{ private static Map<String , Goods> map = new LinkedHashMap(); static { map.put("1",new Goods("1","红楼梦","曹雪芹","中国经典名著 ")); map.put("2",new Goods("2","javaweb开发","白光元","javaweb自学书籍")); map.put("3",new Goods("3","西游记","吴承恩","中国经典名著")); map.put("4",new Goods("4","童年","高尔基","俄国经典名著")); map.put("5",new Goods("5","鲁滨逊漂流记","迪福","英国名著")); map.put("6",new Goods("6","java核心技术","马志强","java教科书")); map.put("7",new Goods("7","javaweb完全自学手册","宝柏","javaweb开发宝典")); map.put("8",new Goods("8","动态网站开发","萧萧","javaweb书籍")); } public static Map getAll(){ return map; } } class Goods{ private String id ; private String name; private String author; private String description; public Goods() { super(); // TODO Auto-generated constructor stub } public Goods(String id, String name, String author, String description) { super(); this.id = id; this.name = name; this.author = author; this.description = description; } 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; } public String getAuthor() { return author; } public void setAuthor(String author) { this.author = author; } public String getDescription() { return description; } public void setDescription(String description) { this.description = description; } } 创建cookie；利用返回id显示商品的信息，并且保存在cookie的集合中：最后通过遍历的得到最近浏览的商品； <pre name="code" class="java">package com.cn.cookie; import java.io.IOException; import java.io.PrintWriter; import java.util.Arrays; import java.util.LinkedList; 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 Cookie2 extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //根据用户带来的id，显示商品的详细信息 response.setContentType("text/html;charset=utf-8"); response.setCharacterEncoding("UTF-8"); PrintWriter out = response.getWriter(); String id =request.getParameter("id"); Goods goods = (Goods) Db.getAll().get(id); out.write(goods.getId()+"<br/>"); out.write(goods.getName()+"<br/>"); out.write(goods.getAuthor()+"<br/>"); out.write(goods.getDescription()+"<br/>"); //构建cookie，回写给浏览器 String cookieValue = buildCookie(id,request); Cookie cookie = new Cookie("goodsHistory",cookieValue); cookie.setMaxAge(1*30*24*3600); cookie.setPath("/Userinfo"); response.addCookie(cookie); out.print("<a href = '/Userinfo/Cookie1'>返回首页</a>"); } private String buildCookie(String id, HttpServletRequest request) { String goodsHistory = null; Cookie cookies[] =request.getCookies(); for(int i = 0;cookies!=null&&i<cookies.length;i++){ if(cookies[i].getName().equals("goodsHistory")){ goodsHistory = cookies[i].getValue(); } } if(goodsHistory ==null){ return id; } LinkedList<String> list =new LinkedList(Arrays.asList(goodsHistory.split("\\,"))); if(list.contains(id)){ list.remove(id); list.addFirst(id); }else{ if(list.size()>=3){ list.removeLast(); list.addFirst(id); }else{ list.addFirst(id); } } StringBuilder sb =new StringBuilder(); for(String bid:list){ sb.append(bid+","); } return sb.deleteCharAt(sb.length()-1).toString(); } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }