December 2003
Intermediate to advanced
764 pages
24h 58m
English
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URL Rewriting
As I mentioned earlier, the session ID needed to keep track of requests within the same session can be transferred between the server and the browser in a number of different ways. One way is to encode it in the URLs created by the JSP pages. This is called URL rewriting. It’s an approach that works even if the browser doesn’t support cookies (perhaps because the user has disabled them). A URL with a session ID looks like this:
counter2.jsp;jsessionid=be8d691ddb4128be093fdbde4d5be54e00
When the user clicks on a link with an encoded URL, the server extracts the session ID from the request URI and associates the request with the correct session. The JSP page can then access the session data in the same way as when cookies keep track of the session ID, so you don’t have to worry about how it’s handled. What you do need to do, however, is tell the JSP container to encode the URL when needed. To see how it’s done, let’s add HTML links in the counter page—one link without rewriting and one with. Example 10-5 shows a counter page with this addition.
Example 10-5. A page with links, with and without URL rewriting (counter2.jsp)
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<html>
<head>
<title>Counter page</title>
</head>
<body bgcolor="white">
<%-- Increment the counter --%>
<c:set var="sessionCounter" scope="session"
value="${sessionCounter + 1}" />
<h1>Counter page</h1>
This page has been visited <b>${sessionCounter}</b> times within the current session. ...Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.