JSTL (JavaServer Pages Standard Tag Library) in Advanced Java Programming, Slides of Java Programming

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Advanced Java Programming

Lecture 12 - JSTL (JSP Standard Tag Library) Reference: JAVA EE 5 TUTORIAL

Agenda

 What is and Why JSTL?  JSTL Functional areas  Core tags  Database Access tags  XML tags  Quick review on XPath  Internationalization and Text Formatting tags  EL (Expression Language) functions tags

What is JSTL?

 Standard set of tag libraries  Encapsulates core functionality common to many JSP applications  iteration and conditionals  XML  database access  internationalized formatting  Likely to evolve to add more commonly used tags in future versions

Why JSTL?

 You don't have to write them yourself  You learn and use a single standard set of tag libraries that are already provided by compliant Java EE platforms  Vendors are likely to provide more optimized implementation  Portability of your applications are enabled

Declaration of JSTL Tag Libraries  Core  <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>  XML  <%@ taglib prefix="x" uri="http://java.sun.com/jsp/jstl/xml" %>  Internationalization (i 18 n)  <%@ taglib prefix="fmt" uri="http://java.sun.com/jsp/jstl/fmt" %>  Database (SQL)  <%@ taglib prefix="sql" uri="http://java.sun.com/jsp/jstl/sql" %>  Functions  <%@ taglib prefix="fn" uri="http://java.sun.com/jsp/jstl/functions" %>

Core Tags

(Core Actions)

Core Tags Types (page 2 )

 URL management  <c:import>  <c:param>  <c:redirect>  <c:param>  <c:url>  <c:param>  General purpose  <c:out>  <c:catch>

Variable Support, <c:set>

 Sets the value of an EL variable or the property of an EL variable via “var” attribute  in any of the JSP scopes via “scope” attribute  page, request, session, application  If the variable does not already exist, it gets created and saved (in the scope object)  Variable can be set in 2 different ways  <c:set var="foo" scope="session" value="..."/>  example: <c:set var="bookId" value="${param.BookID}"/>  <c:set var="foo">value to be set</c:set>

Example: How a predefined Variable

“customerTable” is used: ./elsupport/Set2.jsp

<h 4 >Using "customerTable" application scope attribute defined in Set.jsp a first time</h 4 > <c:out value="${customerTable}" escapeXml="false"/> <h 4 >Using "customerTable" application scope attribute defined in Set.jsp a second time</h 4 > <c:out value="${customerTable}" escapeXml="false" />

Example: How a predefined Variable

“customerTable” is used: ./elsupport/Set 2 .jsp

Conditional Tags

 Flow control tags eliminate the need for scriptlets  Without conditional tags, a page author must generally resort to using scriptlets in JSP page  <c:if test=”..”>  Conditional execution of its body according to value of a test attribute  <c:choose>  Performs conditional block execution by the embedded <c:when> and <c:otherwise> sub tags  Works like if-then-else

Example: <c:if test=”...”>, ./conditionals/If.jsp <c:forEach var="customer" items="${customers}"> <c:if test="${customer.address.country == 'USA'}"> ${customer}
</c:if> </c:forEach> Only the customers whose “address.country” property value is “USA” are displayed through <c:forEach> loop.