March 2008
Intermediate to advanced
911 pages
20h 31m
English
Content preview from Head First Servlets and JSP, 2nd Edition
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,
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.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.I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.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.
A conditional forward...
So imagine you’re a JSP and you assume you’re being called from a request that includes a userName parameter. Since you’re counting on that parameter, you want to first check that the userName parameter isn’t null. If it’s not, no problem—finish the response. But if the userName parameter is null, you want to stop right here and turn the whole request over to something else—like a different JSP that will ask for the userName.
For now, we know we can do it with scripting:
JSP with a conditional forward (Hello.jsp)
JSP to which the request is forwarded (HandleIt.jsp)
<html><body>
We're sorry... you need to log in again.
<form action="Hello.jsp" method="get">
Name: <input name="userName" type="text">
<input name="Submit" type="submit">
</form>
</body></html>Note
This is just a plain old page that gets the request parameter input from the user and then requests the JSP we were just on... Hello.jsp.
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,
and much more.
Read now
Unlock full access
More than 5,000 organizations count on O’Reilly
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.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
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.