The JSP Standard Tag Library (JSTL) represents a set of tags to simplify the JSP
development.
Advantage of JSTL:
1)Fast Developement JSTL provides many tags that simplifies the JSP.
2)Code Reusability We can use the JSTL tags in various pages.
3)No need to use scriptlet tag It avoids the use of scriptlet tag.
There JSTL mainly provides 5 types of tags:
| Tag Name | Description |
| core tags | The JSTL core tag provide variable support, URL management, flow control etc. The url for the core tag is http://java.sun.com/jsp/jstl/core . The prefix of core tag is c. |
| sql tags | The JSTL sql tags provide SQL support. The url for the sql tags is http://java.sun.com/jsp/jstl/sql and prefix is sql. |
| xml tags | The xml sql tags provide
flow control, transformation etc. The url for the xml tags is
http://java.sun.com/jsp/jstl/xml and prefix is x. |
| internationalization tags | The internationalization
tags provide support for message formatting, number and date formatting etc.
The url for the internationalization tags is http://java.sun.com/jsp/jstl/fmt
and prefix is fmt. |
| functions tags | The functions tags provide support for string manipulation and string length. The url for the functions tags is http://java.sun.com/jsp/jstl/functions and prefix is fn. |
For creating JSTL application, you need to load
jstl.jar file.
JSTL Core Tags:
The JSTL core tags mainly provides 4 types of tags:
miscellaneous tags: catch and out.
url management tags: import, redirect and url.
variable support tags: remove and set.
flow control tags: forEach, forTokens, if and choose.
Syntax for defining core tags
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
c:catch:
It is an alternative apporach of global exception handling of JSP. It handles
the exception and doesn't propagate the exception to error page. The exception
object thrown at runtime is stored in a variable named var.
Example of c:catch:
Let's see the simple example of c:catch.
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<c:catch>
int a=10/0;
</c:catch>
c:out:
It is just like JSP expression tag but it is used for exression. It renders data
to the page.
Example of c:out
Let's see the simple example of c:out.
index.jsp
<form action="process.jsp" method="post">
FirstName:<input type="text" name="fname"/><br/>
LastName:<input type="text" name="lname"/><br/>
<input type="submit" value="submit"/>
</form>
process.jsp
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
First Name:<c:out value="${param.fname}"></c:out><br/>
Last Name:<c:out value="${param.lname}"></c:out>
c:import:
It is just like jsp include but it can include the content of any resource
either within server or outside the server.
Example of c:import
Let's see the simple example of c:import to display the content of other site.
index.jsp
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<h1>ABC.com</h1>
<hr/>
<c:import url="http://www.ycd.com"></c:import>
Example of c:import to display the source code
Let's see the simple example of c:import to display the source code of other
site.
index.jsp
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<h1>ABC.com</h1>
<hr/>
<c:import var="data" url="http://www.ycd.com"></c:import>
<h2>Data is:</h2>
<c:out value="${data}"></c:out>
c:forEach:
It repeats the nested body content for fixed number of times or over collection.
Example of c:forEach
Let's see the simple example of c:forEach.
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<c:forEach var="number" begin="5" end="10">
<c:out value="${number}"></c:out>
</c:forEach>
c:if
It tests the condition.
Example of c:if
Let's see the simple example of c:if.
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<c:set var="number" value="${200}">
<c:if test="${number<500}">
<c:out value="number is less than 500"></c:out>
</c:if>
c:redirect
It redirects the request to the given url.
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<c:redirect url="http://www.ycd.com"></c:redirect>