利用cookie显示商品的浏览记录

需求介绍：利用cookie技术，在“你曾经看过的商品 ”列表中显示顾客最新浏览的3件商品（最后一次浏览的在最上边，以此类推）。

主页面为：IndexInf.java

package CookieDemo;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;public class IndexInf extends HttpServlet{public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException{//解决中文乱码问题response.setCharacterEncoding("UTF-8");response.setContentType("text/html;charset=UTF-8");PrintWriter out = response.getWriter();//输出所有商品out.write("网站商品如下 ： </br>");Map<String,Book> map = Db.getAll();for(Map.Entry<String,Book> entry : map.entrySet()){Book book = entry.getValue();out.print("<a target=\"_blank\" href='/CookieTest/servlet/ShowGoodsInf?id="+book.getId()+"'>"+book.getName()+"</a><br/>");}//显示用户看过的商品out.print("<br/>你曾经看过的商品 : <br/>");Cookie[] cookies = request.getCookies();for(int i=0;cookies!=null && i<cookies.length;i++){if(cookies[i].getName().equals("bookHistory")){//将ids以","分割String[] ids = cookies[i].getValue().split("\\,");for(String id : ids){Book book = (Book) Db.getAll().get(id);out.print(book.getName()+"</br>");}}}}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException{doGet(request, response);}}//用类来简单模拟数据库class Db{private static Map<String,Book> map = new LinkedHashMap<String, Book>(); static{map.put("1",new Book("1","Java开发","赵钱","好书啊。"));map.put("2",new Book("2","JavaWeb开发","孙李","好书啊。"));map.put("3",new Book("3","Jdbc开发","周武","好书啊。"));map.put("4",new Book("4","Spring开发","郑王","好书啊。"));map.put("5",new Book("5","Android开发","马六","好书啊。"));}public static Map getAll(){return map;}}//创建Book类class Book{private String id;private String name;private String author;private String description;public Book(){super();}public Book(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;}}

显示商品信息页面为ShowGoodsInf.java：

package CookieDemo;import java.io.IOException;import java.io.PrintWriter;import java.util.ArrayList;import java.util.Arrays;import java.util.LinkedList;import java.util.List;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 ShowGoodsInf extends HttpServlet{public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException{//解决中文乱码问题response.setCharacterEncoding("UTF-8");response.setContentType("text/html;charset=UTF-8");PrintWriter out = response.getWriter();//根据用户传送过来的id显示商品的详细信息String id = request.getParameter("id");Book book = (Book) Db.getAll().get(id);out.write(book.getId()+"</br>");out.write(book.getAuthor()+"</br>");out.write(book.getName()+"</br>");out.write(book.getDescription()+"</br>");//构建Cookie,回写给浏览器String cookieValue = buildCookie(id,request);Cookie cookie = new Cookie("bookHistory",cookieValue);cookie.setMaxAge(30*24*60*60);cookie.setPath("/CookieTest");response.addCookie(cookie);} private String buildCookie(String id, HttpServletRequest request){String bookHistory = null;Cookie[] cookies = request.getCookies();for(int i=0;cookies!=null && i<cookies.length;i++){if(cookies[i].getName().equals("bookHistory")){bookHistory = cookies[i].getValue();}}if (bookHistory==null){return id;}//将数组转换成集合LinkedList<String> list = new LinkedList(Arrays.asList(bookHistory.split("\\,")));if(list.contains(id)){list.remove(id);}else if(list.size()>=3)    //控制显示用户浏览过的商品最多为3个{list.removeLast();}list.addFirst(id);StringBuffer sb = new StringBuffer();for(String bookId : list){sb.append(bookId+",");}return sb.deleteCharAt(sb.length()-1).toString();}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException{doGet(request, response);}}

两者在web.xml中的配置为：

<?xml version="1.0" encoding="UTF-8"?><web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">  <display-name></display-name>  <servlet>    <servlet-name>IndexInf</servlet-name>    <servlet-class>CookieDemo.IndexInf</servlet-class>  </servlet>  <servlet>    <servlet-name>ShowGoodsInf</servlet-name>    <servlet-class>CookieDemo.ShowGoodsInf</servlet-class>  </servlet>  <servlet-mapping>    <servlet-name>IndexInf</servlet-name>    <url-pattern>/servlet/IndexInf</url-pattern>  </servlet-mapping>  <servlet-mapping>    <servlet-name>ShowGoodsInf</servlet-name>    <url-pattern>/servlet/ShowGoodsInf</url-pattern>  </servlet-mapping>  <welcome-file-list>    <welcome-file>index.jsp</welcome-file>  </welcome-file-list></web-app>

运行结果：

当浏览主页时：

点击“Spring开发”后跳转页面至：

通过一系列浏览后，刷新主显示页面后看到：