December 2003
Intermediate to advanced
764 pages
24h 58m
English
Content preview from JavaServer Pages, 3rd EditionBecome 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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All Together Now
At this point,
you have seen
the two mechanisms needed to let multiple pages process the same
request: passing control and passing data. These mechanisms allow you
to employ the MVC design, using one page for request processing and
business logic, and another for presentation. The
<jsp:forward>
action can pass control between the pages, and information placed in
the request scope is available to all pages processing the same
request.
Let’s apply this to the User Info example. In Chapter 8, different output was produced depending on whether or not the user input was valid. If the input was invalid, error messages were added to inform the user of the problem. Even when the input was valid, however, the form—without error messages, of course—was displayed.
No more of that. When we split the different aspects of the application into separate JSP pages as shown in Figure 10-1, we also change the example so that the form is only shown when something needs to be corrected. When all input is valid, a confirmation page is shown instead.
Example 10-1 shows the top part of the userinfoinput.jsp page.
Example 10-1. Page for displaying entry form (userinfoinput.jsp)
<%@ page contentType="text/html" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<html>
<head>
<title>User Info Entry Form</title>
</head>
<body bgcolor="white">
<jsp:useBean id="userInfo"
scope="request"
class="com.ora.jsp.beans.userinfo.UserInfoBean"
/>
<form action="userinfovalidate.jsp" method="post"> ...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.
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.