JavaWeb -- Cookie应用实例 -- 购物历史记录

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页面一：主页面                                         页面二： 详细显示页面

 

Demo2 负责页面一， 显示商品清单和历史记录

Demo3负责页面二，显示商品详细内容 和  写入相应的Cookie

SevletDemo2 代码：

 

package com.kevin;import java.io.IOException;import java.io.PrintWriter;import java.util.LinkedHashMap;import java.util.Map;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;/** * Servlet implementation class Demo2 */@WebServlet("/Demo2")public class Demo2 extends HttpServlet {private static final long serialVersionUID = 1L;           /**     * @see HttpServlet#HttpServlet()     */    public Demo2() {        super();        // TODO Auto-generated constructor stub    }/** * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response) */protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {// TODO Auto-generated method stubresponse.setCharacterEncoding("UTF-8");response.setContentType("text/html;charset=UTF-8");PrintWriter out = response.getWriter();//1.display all commodityout.write("本网站所有商品如下：<br/>");Map<String, Book> map = Db.getAll();for(Map.Entry<String, Book> entry : map.entrySet()){Book book = entry.getValue();out.print("<a href='/WebTest3/Demo3?id="+ book.getId() +"' target='_blank'>"+ book.getName() +"</a>" + "<br/>");}//2.display book historyout.print("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") ){String[] ids = cookies[i].getValue().split("\\,");for(String id : ids){//System.out.println("id=" + id);Book book = (Book) Db.getAll().get(id);out.print(book.getName() + "<br/>");}}}}/** * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response) */protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {// TODO Auto-generated method stub}}class Db{private static Map<String, Book> map = new LinkedHashMap<String, Book>();static{map.put("1", new Book("1", "JavaWeb", "zhangsan", "a good book"));map.put("2", new Book("2", "Jdbc", "lisi", "a good book"));map.put("3", new Book("3", "Spring", "wangwu", "a good book"));map.put("4", new Book("4", "Struts", "zhaoliu", "a good book"));map.put("5", new Book("5", "Android", "zhangfa", "a good book"));}public static Map getAll(){return map;}}class Book{private String id;private String name;private String author;private String description;public Book() {super();// TODO Auto-generated constructor stub}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;}}

ServletDemo3代码：

package com.kevin;import java.io.IOException;import java.io.PrintWriter;import java.util.Arrays;import java.util.LinkedList;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;/** * Servlet implementation class Demo3 */@WebServlet("/Demo3")public class Demo3 extends HttpServlet {private static final long serialVersionUID = 1L;           /**     * @see HttpServlet#HttpServlet()     */    public Demo3() {        super();        // TODO Auto-generated constructor stub    }/** * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response) */protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {// TODO Auto-generated method stubresponse.setCharacterEncoding("UTF-8");response.setContentType("text/html;charset=UTF-8");PrintWriter out = response.getWriter();//out.print("Demo3");//1. display detail info by idString id = request.getParameter("id");Book book = (Book) Db.getAll().get(id);if(book !=null){out.write(book.getId() + "<br/>");out.write(book.getAuthor() + "<br/>");out.write(book.getName() + "<br/>");out.write(book.getDescription() + "<br/>");}//2. write cookieString cookieValue = buildCookie(id, request);Cookie cookie = new Cookie("bookHistory", cookieValue);cookie.setMaxAge(30*24*3600);cookie.setPath("/WebTest3");response.addCookie(cookie);}private String buildCookie(String id, HttpServletRequest request) {//max num = 3//bookHistory=null    look:1     return:1 //bookHistory=2,3,4   look:4     return:4,2,3//bookHistory=2,3,4   look:1     return:1,2,5//bookHistory=2,3     look:4     return:2,3,4 String bookHistory = null;Cookie[] cookies = request.getCookies();for(int i=0; cookies!=null && i<cookies.length; i++){if( cookies[i].getName().equals("bookHistory") ){System.out.println("hava bookHistory");bookHistory = cookies[i].getValue();}}System.out.println("bookHistory=" + bookHistory);if(bookHistory==null)return id;LinkedList<String> list = new LinkedList<String>(Arrays.asList(bookHistory.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);}}StringBuffer sb = new StringBuffer();for(String id2 : list){sb.append(id2 + ",");}return sb.deleteCharAt(sb.length()-1).toString();}/** * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response) */protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {// TODO Auto-generated method stub}}