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Using JSTL

JSTL includes a wide variety of tags that naturally fit into discrete functional areas. Therefore, JSTL is exposed via multiple tag library descriptors (TLDs) to clearly show the functional areas it covers and give each area its own namespace. Table 16-1 summarizes these functional areas along with the logical TLD names and prefixes used in this chapter and Duke's Bookstore application.

Table 16-1 JSTL Tags 

Area	Function	Tags	TLD	Prefix
Core	Expression Language Support	catch out remove set	/jstl-c	c
	Flow Control	choose   when   otherwise forEach forTokens if
	URL Management	import   paramredirect   param url   param
XML	Core	out parse set	/jstl-x	x
	Flow Control	choose  when  otherwise forEach if
	Transformation	transform   param
I18n	Locale	setLocale	/jstl-fmt	fmt
	Message formatting	bundle message   param setBundle
	Number and dateformatting	formatNumber formatDate parseDate parseNumber setTimeZone timeZone
Database		setDataSource	/jstl-sql	sql
	SQL	query   dateParam   param transaction update  dateParam   param

For example, to use the JSTL core tags in a JSP page, you declare the library using a taglib directive that references the TLD:

<%@ taglib uri="/jstl-core" prefix="c" %>
 

The JSTL tag libraries comes in two versions (see Twin Libraries). The TLDs for the JSTL-EL library are named prefix.tld. The TLDs for the JSTL-RT library are named prefix-rt.tld. Since the examples discussed in this chapter use logical TLD names, we map the logical names to actual TLD locations with taglib elements in the Web application deployment descriptor. Here is the entry that maps the core library logical TLD name /jstl-c to its location /WEB-INF/c.tld:

<taglib>
  <taglib-uri>/jstl-c</taglib-uri>
  <taglib-location>/WEB-INF/c.tld</taglib-location>
</taglib>
 

In the Java WSDP, the JSTL TLDs are stored in <JWSDP_HOME>/tools/jstl/tlds. When you build the Duke's Bookstore application these TLDs are automatically copied into <JWSDP_HOME>/docs/tutorial/examples/web/bookstore4/build/WEB-INF.

You can also reference a TLD in a taglib directive with an absolute URI:

• Core: http://java.sun.com/jstl/core
• XML: http://java.sun.com/jstl/xml
• Internationalization: http://java.sun.com/jstl/fmt
• SQL: http://java.sun.com/jstl/sql

When you use an absolute URI, you do not have to add the taglib element to web.xml; the JSP container automatically locates the TLD inside the JSTL library implementation.

In addition to declaring the tag library, you also need to make the JSTL API and implementation available to the Web application. These are distributed as the archives jstl.jar in <JWSDP_HOME>/tools/jstl and standard.jar in <JWSDP_HOME>/tools/jstl/standard. When you build the Duke's Bookstore application these libraries are automatically copied into <JWSDP_HOME>/docs/tutorial/examples/web/bookstore4/build/WEB-INF/lib.

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This tutorial contains information on the 1.0 version of the Java Web Services Developer Pack.

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