Declaring a Custom Tag Library
As you
know by now, a JSP page contains a mixture of JSP elements and
template text, in which the template text can be HTML or XML
elements. The JSP container needs to figure out which is which.
It’s easy for it to recognize the standard JSP
elements (because they all use the jsp
namespace
prefix), but it needs some help to find the elements that represent
custom actions. That’s where the tag library
declaration comes into play.
Example 7-1 shows a page that uses a custom action from a custom tag library.
<%@ page contentType="text/html" %>
<%@ taglib prefix="ora" uri="orataglib" %>
<html>
<head>
<title>Messages of the Day</title>
</head>
<body bgcolor="white">
<h1>Messages of the Day</h1>
<h2>Deep Thoughts - by Jack Handey</h2>
<i>
<ora:motd category="thoughts" />
</i>
<h2>Quotes From the Famous and the Unknown</h2>
<i>
<ora:motd category="quotes" />
</i>
</body>
</html>
This page displays messages from the same collections as the examples
in Chapter 6. The second directive in Example 7-1 is a taglib
directive,
which is used to declare a custom tag library. Now,
let’s see what this really means. In order for the
JSP container to use actions from a tag library, it must be able to
do two things: recognize that an element represents a custom action
from a specific library, and find the Java class or tag file that
implements the custom action logic.
The first requirement—figuring out which library ...
Get JavaServer Pages, 3rd Edition now with the O’Reilly learning platform.
O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.