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案例目标
将用户最近浏览的商品信息,在主页回显,若浏览的商品大于3个,就把第一个删除,同时若有重复的浏览,就把之前的商品信息删除
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index.jsp用于回显最近浏览的商品信息
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<a href="commodityDetails.jsp?name=lenovo">联想</a><br/>
<a href="commodityDetails.jsp?name=apple">苹果</a><br/>
<a href="commodityDetails.jsp?name=asus">华硕</a><br/>
<a href="commodityDetails.jsp?name=microStar">微星</a><br/>
<a href="commodityDetails.jsp?name=shenzhou">神州</a><br/>
<a href="commodityDetails.jsp?name=et">外星人</a>
<br/>
<br/>
<br/>
<%
//用于回显最近浏览的商品信息
Cookie [] cookies = request.getCookies();
if( cookies!=null && cookies.length>0){
for( Cookie tmpCookie : cookies){
if(tmpCookie.getName().startsWith("NOTEBOOK_")){
out.print(tmpCookie.getValue());
out.print("<br/>");
}
}
}
%>
</body>
</html>
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CommodityDetails.jsp用于显示商品详情,以及处理Cookie
<%@page import="java.util.ArrayList"%>
<%@page import="java.util.List"%>
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<%
//获取新点击的商品名称
String commodity = request.getParameter("name");
//拼接字符串组成Cookie的键值,以NOTEBOOK_开头与其他Cookie进行区分
String cookieKey = "NOTEBOOK_"+commodity;
//定义待删除的Cookie
Cookie waitingForDelCookie=null;
//获取所有Cookie
Cookie [] cookies = request.getCookies();
//新建List用于保存商品Cookie
List<Cookie> listCookie = new ArrayList<Cookie>();
//遍历所有Cookie,将与商品有关的Cookie加入List,同时判断有没有重复点击的商品
if( cookies!=null && cookies.length>0 ){
System.out.println("cookies!=null");
for( Cookie tmpCookie : cookies ){
if(tmpCookie.getName().startsWith("NOTEBOOK_")){
listCookie.add(tmpCookie);
if(tmpCookie.getName().equals(cookieKey)){
waitingForDelCookie=tmpCookie;
}
}
}
}
//如果与商品有关的Cookie大于3,还没有待删除的Cookie,就把首个Cookie删除
if(listCookie.size()>3 && waitingForDelCookie==null ){
waitingForDelCookie=listCookie.get(0);
}
/**
*注意删除的Cookie也要回传
*/
if(waitingForDelCookie!=null){
waitingForDelCookie.setMaxAge(0);
response.addCookie(waitingForDelCookie);
}
//添加新点击的商品。组成的Cookie
Cookie cookie = new Cookie(cookieKey,commodity);
response.addCookie(cookie);
%>
<h3>commodityDetails</h3>
<a href="index.jsp">Return....</a>
</body>
</html>