Struts

Using the JSP
Standard Tag Library
(JSTL) with Struts
Core Servlets & JSP book: www.coreservlets.com
More Servlets & JSP book: www.moreservlets.com
Servlet and JSP Training Courses: courses.coreservlets.com
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Slides © Marty Hall, http://www.moreservlets.com, book © Sun Microsystems Press

For live Struts training, please see
JSP/servlet/Struts/JSF training courses athttp://courses.coreservlets.com/.
Taught by the author of Core Servlets and JSP, More
Servlets and JSP, and this tutorial. Available at public
venues, or customized versions can be held on-site at
your organization.
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Slides © Marty Hall, http://www.moreservlets.com, book © Sun Microsystems Press

Agenda
• Obtaining JSTL documentation and code
• The JSTL Expression Language
• Looping Tags
– Loopinga certain number of times
– Looping over data structures

• Conditional Evaluation Tags
– Single choice
– Multiple choices

• Database Access Tags
• Other Tags
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JSTL 1.0

www.moreservlets.com

Overview and
Installation

5

Slides © Marty Hall, http://www.moreservlets.com, book © Sun Microsystems Press

JSTL Overview
• JSTL is the recommended replacement for
the Strutslooping and logic tags
• JSTL is not part of the JSP 1.2 or 2.0 Specs
– It is a separate specification that requires a separate
download

– Available only in servers that support servlets 2.3 and
JSP 1.2 or later. Cannot be retrofitted into JSP 1.1.

• The JSTL expression language is now
part of JSP 2.0
• The JSTL Specification is available in PDF
–http://jcp.org/aboutJava/communityprocess/final/jsr052/
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www.moreservlets.com

JSTL 1.0

Installing JSTL
• Some servers come with JSTL preinstalled
– E.g., Caucho Resin

• Official reference implementation
– http://jakarta.apache.org/builds/jakarta-taglibs/releases/standard/

• JSTL (like JSP) is a specification, not an
implementation
– Code is portable but not all versions are equal

• Speed, tools, anddevelopment environments
vary
• To install:

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– Download zip file
– Unzip into directory of your choice (e.g., C:\jakarta-taglibs).
– Copy install_dir/standard-1.0.1/lib/jstl.jar and
install_dir/standard-1.0.1/lib/standard.jar to the WEB-INF/lib
www.moreservlets.com
directory of your Web application
JSTL 1.0

The JSTL Expression Language
• Accessed via ${expression}
• Similar toJavaScript and XPath
• Provides shorthand notation to access:
– Attributes of standard servlet objects
– Bean properties
– Map, List, and Array elements

• Is standard part of JSP 2.0
– In JSTL, EL can be used only in attributes of JSTL tags
– In JSP 2.0, the EL can be used anywhere
• web.xml element and page directive attribute let you disable the
EL for backward compatibility

• Covered inseparate lecture
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JSTL 1.0

www.moreservlets.com

Iteration Tags

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Slides © Marty Hall, http://www.moreservlets.com, book © Sun Microsystems Press

Looping Tags: Summary
• Looping with explicit numeric values

Blah, blah


• Looping over data structures
– Can loop down arrays, strings, collections, maps

Blah, blah


• Looping down delimited strings
– forTokens
10JSTL 1.0

www.moreservlets.com

Looping Tags: Motivation
• JSP without JSTL


(greater than 7)




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JSTL 1.0

www.moreservlets.com

The "if" Tag (Results)

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JSTL 1.0

www.moreservlets.com

The "choose" Tag






(small)


(medium)


(large)




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JSTL 1.0

www.moreservlets.com

The "choose" Tag (Results)

25

JSTL 1.0www.moreservlets.com

Database Access
Tags

Slides © Marty Hall, http://www.moreservlets.com, book © Sun Microsystems Press

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Database Access Tags
•
– Specifies data source (can also be set by config settings)

•
– Queries database and stores ResultSet in variable
– Warning: this usage violates rule of keeping business
logic out of presentation layer. Instead, do database
access in...