DZone
Thanks for visiting DZone today,
Edit Profile
  • Manage Email Subscriptions
  • How to Post to DZone
  • Article Submission Guidelines
Sign Out View Profile
  • Post an Article
  • Manage My Drafts
Over 2 million developers have joined DZone.
Log In / Join
Refcards Trend Reports Events Over 2 million developers have joined DZone. Join Today! Thanks for visiting DZone today,
Edit Profile Manage Email Subscriptions Moderation Admin Console How to Post to DZone Article Submission Guidelines
View Profile
Sign Out
Refcards
Trend Reports
Events
Zones
Culture and Methodologies Agile Career Development Methodologies Team Management
Data Engineering AI/ML Big Data Data Databases IoT
Software Design and Architecture Cloud Architecture Containers Integration Microservices Performance Security
Coding Frameworks Java JavaScript Languages Tools
Testing, Deployment, and Maintenance Deployment DevOps and CI/CD Maintenance Monitoring and Observability Testing, Tools, and Frameworks
Culture and Methodologies
Agile Career Development Methodologies Team Management
Data Engineering
AI/ML Big Data Data Databases IoT
Software Design and Architecture
Cloud Architecture Containers Integration Microservices Performance Security
Coding
Frameworks Java JavaScript Languages Tools
Testing, Deployment, and Maintenance
Deployment DevOps and CI/CD Maintenance Monitoring and Observability Testing, Tools, and Frameworks

EE JSP: Generating Dynamic Content with JSTL Tag Libraries

Zemian Deng user avatar by
Zemian Deng
·
Feb. 19, 15 · Interview
Like (0)
Save
Tweet
Share
7.36K Views

Join the DZone community and get the full member experience.

Join For Free

Besides writing your own Custom Tags in JSP, you will find that Java EE actually provides a set of Java Standard Tag Library (JSTL) ready for you to use. These built-in tags include repeating (for-loop) tags, if condition tags, variable declaration and output tags etc. The Libraries also come with many utility functions and international message formatting tags. Here is an example how it looks like.

<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%@ taglib prefix="x" uri="http://java.sun.com/jsp/jstl/xml" %>
<%@ taglib prefix="fmt" uri="http://java.sun.com/jsp/jstl/fmt" %>
<%@ taglib prefix="sql" uri="http://java.sun.com/jsp/jstl/sql" %>
<%@ taglib prefix="fn" uri="http://java.sun.com/jsp/jstl/functions" %>
<!DOCTYPE html>
<html>
    <body>
        <h1>JSTL Examples</h1>
        <h2>List of Application Context: ${applicationScope}</h2>
        <table>
            <c:forEach var="entry" items="${applicationScope}">
            <tr>
                <td>${entry.key}</td>
                <td>
                    <c:out value="${entry.value}"/>
                </td>
            </tr>
            </c:forEach>
        </table>
        
        <h2>List of Session Context: ${sessionScope}</h2>
        <table>
            <c:forEach var="entry" items="${sessionScope}">
            <tr>
                <td>${entry.key}</td>
                <td>
                    <c:out value="${entry.value}"/>
                </td>
            </tr>
            </c:forEach>
        </table>
        
        <h2>List of Page Context: ${pageScope}</h2>
        <table>
            <c:forEach var="entry" items="${pageScope}">
            <tr>
                <td>${entry.key}</td>
                <td>
                    <c:out value="${entry.value}"/>
                </td>
            </tr>
            </c:forEach>
        </table>
        
        <h2>List of Request Context: ${requestSope}</h2>
        <table>
            <c:forEach var="entry" items="${requestSope}">
            <tr>
                <td>${entry.key}</td>
                <td>
                    <c:out value="${entry.value}"/>
                </td>
            </tr>
            </c:forEach>
        </table>
        
        <h2>List of Query Parameters: ${param}</h2>
        <table>
            <c:forEach var="entry" items="${param}">
            <tr>
                <td>${entry.key}</td>
                <td>
                    <c:out value="${entry.value}"/>
                </td>
            </tr>
            </c:forEach>
        </table>
        
        <h2>List of Header Parameters: ${header}</h2>
        <table>
            <c:forEach var="entry" items="${header}">
            <tr>
                <td>${entry.key}</td>
                <td>
                    <c:out value="${entry.value}"/>
                </td>
            </tr>
            </c:forEach>
        </table>        
        
        <h2>List of Cookies: ${cookie}</h2>
        <table>
            <c:forEach var="entry" items="${cookie}">
            <tr>
                <td>${entry.key}</td>
                <td>
                    <c:out value="${entry.value}"/>
                </td>
            </tr>
            </c:forEach>
        </table>
    </body>
</html>

I used the core tag here to display map entries of few implicit variables. You may explore more on those tags declarations I have define on top of the example page from the Spec. These code are from the jsp-example from GitHub.

GLASSFISH NOTE: When deploying above example in GlassFish 3/4, you will run into a NullPointerExceptionand causing the page resulted in error. It turns out that GF server added a internal variable namedcom.sun.jsp.taglibraryCache  in ServletContext (Application Scope) that throws NPE when its toString()is called! To workaround this, I created jstl-example2.jsp that wraps the ${entry.value} into a custom JSTL function so that it guarantees to return an output without throwing exception. So the lesson learned is that you should always return a String and not throw Exception when overriding toString() of a Java class. It's just bad practice.

Library

Published at DZone with permission of Zemian Deng, DZone MVB. See the original article here.

Opinions expressed by DZone contributors are their own.

Popular on DZone

  • Key Considerations When Implementing Virtual Kubernetes Clusters
  • 5 Factors When Selecting a Database
  • Bye-Bye, Regular Dev [Comic]
  • How to Secure Your CI/CD Pipeline

Comments

Partner Resources

X

ABOUT US

  • About DZone
  • Send feedback
  • Careers
  • Sitemap

ADVERTISE

  • Advertise with DZone

CONTRIBUTE ON DZONE

  • Article Submission Guidelines
  • Become a Contributor
  • Visit the Writers' Zone

LEGAL

  • Terms of Service
  • Privacy Policy

CONTACT US

  • 600 Park Offices Drive
  • Suite 300
  • Durham, NC 27709
  • support@dzone.com
  • +1 (919) 678-0300

Let's be friends: