The set of significant tags a JSP container interprets can be extended through a tag library.
The taglib directive in a JSP page declares that the page uses a tag library, uniquely identifies the tag library using a URI and associates a tag prefix that will distinguish usage of the actions in the library.
If a JSP container implementation cannot locate a tag library description, a fatal translation error shall result.
It is a fatal translation error for the taglib directive to appear after actions or functions using the prefix.
In the following example, a tag library is introduced and made available to this page using the super prefix; no other tag libraries should be introduced in this page using this prefix. In this particular case, we assume the tag library includes a doMagic element type, which is used within the page.
<%@ taglib uri="http://www.mycorp/supertags" prefix="super" %> <super:doMagic> ... </super:doMagic>
Syntax:
<%@ taglib ( uri="tagLibraryURI" | tagdir="tagDir" ) prefix="tagPrefix" %>
Table 9.1. taglib Directive attributes
| Attribute | Description |
|---|---|
| uri | Either an absolute URI or a relative URI specification that uniquely identifies the tag library descriptor associated with this prefix. The URI is used to locate a description of the tag library. |
| tagdir | Indicates this prefix is to be used to identify tag extensions installed in the /WEB-INF/tags/ directory or a subdirectory. An implicit tag library descriptor is used. A translation error must occur if the value does not start with /WEB-INF/tags/. A translation error must occur if the value does not point to a directory that exists. A translation error must occur if used in conjunction with the uri attribute. |
| prefix | Defines the prefix string in <prefix:tagname> that is used to distinguish a custom action, e.g <myPrefix:myTag>. Prefixes starting with jsp:, jspx:, java:, javax:, servlet:, sun:, and sunw: ARE RESERVED. A prefix must follow the naming convention specified in the XML namespaces specification. Empty prefixes are illegal in this version of the specification, and must result in a translation error. |
A fatal translation-time error will result if the JSP page translator encounters a tag with name prefix:Name using a prefix that is introduced using the taglib directive, and Name is not recognized by the corresponding tag library.
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