ps:不能以books：作为标识符（冒号），但是可以用books，好像还可以用--，不知道为什么
books.jsp
<%--
Created by IntelliJ IDEA.
User: Skye
Date: 2017/12/12
Time: 10:23
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<body>
<h4>Book Page</h4>
<a href="book.jsp?book=JavaWeb">JavaWeb</a><br>
<a href="book.jsp?book=Java">Java</a><br>
<a href="book.jsp?book=JavaScript">JavaScript</a><br>
<a href="book.jsp?book=MySQL">MySQL</a><br>
<a href="book.jsp?book=Ajax">Ajax</a><br>
<a href="book.jsp?book=TCPIP">TCPIP</a><br>
<a href="book.jsp?book=Spring">Spring</a><br>
<a href="book.jsp?book=Hibernate">Hibernate</a><br>
<a href="book.jsp?book=Struts">Struts</a><br>
<br>
<%
//显示最近浏览的 5 本书
Cookie[] cookies = request.getCookies();
//获取所有的 Cookie
if(cookies != null && cookies.length > 0){
//从中筛选出 Book 的 Cookie：
for(Cookie cc: cookies){
String bookName = cc.getName();
//如果 cookieName 为books 开头的即符合条件
if(bookName.startsWith("books")){
//显示 cookieValue
out.print(cc.getValue());
out.print("<br>");
}
}
}
%>
</body>
</html>
book.jsp
<%@ page import="java.util.List" %>
<%@ page import="java.util.ArrayList" %><%--
Created by IntelliJ IDEA.
User: Skye
Date: 2017/12/12
Time: 10:22
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<body>
<h4>Book Detail Page</h4>
Book: <%= request.getParameter("book") %>
<a href="books.jsp">Return</a>
<%
//把书的信息以 Cookie 方式传回给浏览器，删除一个 Cookie
String book = request.getParameter("book");
//每次都重新读取浏览器中Cookie的信息，进行存储
List<Cookie> cookies = new ArrayList<Cookie>();
Cookie temp = null;
Cookie[] c = request.getCookies();
if(c!= null && c.length > 0){
for(Cookie cc : c){
String bookName = cc.getName();
//确定要被删除的 Cookie:books开头的 Cookie
if(bookName.startsWith("books")){
cookies.add(cc);
//若已经存储在浏览器的Cookie信息中
if(cc.getValue().equals(book)){
temp = cc;
}
}
}
}
//若List中的书的信息超过了5本，且本次读取的书不在List中，则删除最早的一本
if(cookies.size() >= 5 && temp == null){
temp = cookies.get(0);
}
//删除该书的信息
if(temp != null){
temp.setMaxAge(0);
//删除时用的是先设置最大时效为0，再加入Cookie
response.addCookie(temp);
}
//把从 books.jsp 传入的 book 作为一个 Cookie 返回
Cookie cookie = new Cookie("books" + book, book);
response.addCookie(cookie);
%>
</body>
</html>