javaWEB总结(19):利用Cookie显示最近浏览的商品
前言:淘宝上经常能看到游览过的商品一栏,显示最近浏览的商品指定条数,并且不会重复显示,下面是一个类似的小demo。
需求:记录最近5次的游览记录,并且重复显示的为最新记录。
目录结构
web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
<display-name>javaWeb_19</display-name>
<welcome-file-list>
<welcome-file>books.jsp</welcome-file>
</welcome-file-list>
</web-app>
books.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!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>books.jsp</title>
</head>
<body>
<a href="book.jsp?bookName=java">java</a><br></br>
<a href="book.jsp?bookName=c">c</a><br></br>
<a href="book.jsp?bookName=python">python</a><br></br>
<a href="book.jsp?bookName=vb">vb</a><br></br>
<a href="book.jsp?bookName=php">php</a><br></br>
<a href="book.jsp?bookName=js">js</a><br></br>
<a href="book.jsp?bookName=go">go</a><br></br>
<a href="book.jsp?bookName=r">r</a><br></br>
<%
//获取所有cookies
Cookie[] cookies = request.getCookies();
//循环
if(null!=cookies&&cookies.length!=0){
for(Cookie c :cookies){
if(c.getName().startsWith("DAO"))
{
out.println(c.getValue());
}
}
}
%>
</body>
</html>
book.jsp
<%@page import="java.util.ArrayList"%>
<%@page import="java.util.List"%>
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!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>book.jsp</title>
</head>
<body>
book:<%=request.getParameter("bookName") %><br><br>
<%
String bookName=request.getParameter("bookName");
//获取所有cookies
Cookie[] cookies = request.getCookies();
//保存所有以DAO开头的cookie
List<Cookie> cookieList = new ArrayList<Cookie>();
//存储要删除的cookie
Cookie tempCookie =null;
//循环
if(null!=cookies&&cookies.length!=0){
for(Cookie c :cookies){
//将符合条件的cookie放在list中
if(c.getName().startsWith("DAO")){
cookieList.add(c);
//cookie中已有和bookName相同的值
if(c.getValue().equals(bookName)){
tempCookie = c;
}
}
}
}
if(cookieList.size()>=5&&tempCookie==null){
tempCookie = cookieList.get(0);
}
//符合删除条件,删除该cookie并且回传
if(tempCookie!=null){
tempCookie.setMaxAge(0);
response.addCookie(tempCookie);
}
//将bookName存在cookie中,并且返回
Cookie cookie = new Cookie("DAO"+bookName,bookName);
response.addCookie(cookie);
%>
<a href="books.jsp">返回</a>
</body>
</html>
选择五件商品后,选择java并返回
结果
选择五件商品后(其中包括php),再选择php
结果