Java Web Cookie网上购物实例

package cn.com;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 CookieDemo3 extends HttpServlet {private static final long serialVersionUID = 1L;protected 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();//输出所有的商品out.write("本网站有如下商品：<br/>");Map<String ,Book > map=Db.getAll();for(Map.Entry<String, Book> entry:map.entrySet()){Book book=entry.getValue();out.print("<a href='/Cookie/CookieDemo4?id="+book.getId()+"' target='_blank' >"+book.getName()+"</a><br/>");}//显示用户曾经看过的商品out.print("<br/>您曾经看过的商品：<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){Book book=(Book)Db.getAll().get(id);out.print(book.getName()+"<br/>");}}}}protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {doGet(request,response);}}//Db作为数据库class Db{private static Map<String ,Book> map=new LinkedHashMap();static{map.put("1", new Book("1","Java WEB开发","WY","好书"));map.put("2", new Book("2","WEB开发","zt","一般"));map.put("3", new Book("3","程序设计","df","较好书"));map.put("4", new Book("4","计算机组成","as","一般好书"));map.put("5", new Book("5","编译原理","ty","很好书"));map.put("6", new Book("6","网络维护","hj","非常好书"));}public static Map getAll(){return map;}}//书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;}}package cn.com;import java.io.IOException;import java.io.PrintWriter;import java.util.Arrays;import java.util.Iterator;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;/** * Servlet implementation class CookieDemo4 */public class CookieDemo4 extends HttpServlet {private static final long serialVersionUID = 1L;    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {response.setCharacterEncoding("UTF-8");response.setContentType("text/html;charset=UTF-8");PrintWriter out=response.getWriter();//根据用户带过来的id ,显示响应商品的详细信息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.getDescription()+"<br/>"); out.write(book.getName()+"<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*3600);cookie.setPath("/Cookie");response.addCookie(cookie);}private String buildCookie(String id, HttpServletRequest request) {// TODO Auto-generated method stub//如果用户没有带任何的Cookie过来//如果用户带了Cookie来了包含在看过的id中，则要把id删掉//带了Cookie过来了但是没有包含看过的id//带了Cookie过来但是没有包含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;}LinkedList list=new LinkedList(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);//}//}if(list.contains(id)){list.remove(id);}else if(list.size()>=3){list.removeLast();}list.addFirst(id);StringBuffer sb=new StringBuffer();Iterator it=list.iterator();while(it.hasNext()){String bid=(String)it.next();sb.append(bid+",");}return sb.deleteCharAt(sb.length()-1).toString();}protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {doGet(request,response);}}