JSTL Tags (part - 1)

JSTL tags

The JSTL 1.1 API Specification consists of following packages:

Tag	Description
Core (javax.servlet.jsp.jstl.core)	General purpose actions
Format (javax.servlet.jsp.jstl.fmt)	Internationalization and Localization
SQL (javax.servlet.jsp.jstl.sql)	Common database tasks
Tag Library Validator(javax.servlet.jsp.jstl.tlv)	Tag Library Validators

You can view the api online at http://java.sun.com/products/jsp/jstl/1.1/docs/api/index.html.

Description of JSTL Tags

Core Tags: 

These tags provides the core functionality that a programming language is supposed to provide, such as codition, iteration etc.

1). <c:out>

This tag is used to evaluate an expression and output the result to the current JspWriter object.

Syntax: <c:out value="value" [escapeXml="{true|false}"]  [default="defaultValue"] />

2). <c:forEach>

This tag provide functionality to iterate over an array or collection without using java code.

Syntax: <c:forEach [var="varName"] items = "collection"  [varStatus="varStatusName"] [begin="start"] [end="end"] [step="step"]>

   .... body..
</c:forEach>

3.) <c:if>

This is used for conditional branching within the jsp page based on some test.

Syntax: <c:if  test ="testCondition" var="varName" [scope="{page|request|session|application}"] />

4). <c:set>

This tag is used to set attributes within specified scopes in jsp pages

Syntax: <c:set value="val" var="varname" [scope="{page|request|session|application}"] />

5).  <c:remove>

This tag is used to remove a scoped variable.

Syntax: <c:remove var="varName" [scope="{page|request|session|application}"] />

6).  <c:url>

This tag is used for session management and URL rewriting.

Syntax: <c:url value="value" [context="context"] [var="varName"] [scope="{page|request|session|application}"] />

7).  <c:import>

This is used to include external resources inside the jsp page.

<c:choose>, <c:when> and <c:otherwise> tags

These tags are used for conditional branching, that is provided by switch.... case statement in most programming languages. <c:choose> is used for mutually exclusive conditional execution.

Syntax: <c:choose>..body..... (<when> and <otherwise> subtags) </c:choose>

<c:when> represents an alternative within a <c:choose> action.

Syntax: <c:when test="testCondition">  .... body </c:when>

<c:otherwise> represents the last alternative within a <c:choose> action.

Syntax: <c:otherwise> ..... conditional block..</c:otherwise>

8).  <c:catch>

This tag provide a try...catch like mechanism inside jsp pages without using scriptlets.

Syntax: <c:catch [var="varName"]> .... nested actions </c:catch>

9).  <c:redirect>

This provides same functionality as the sendRedirect() method of HttpServletRequest interface. It is used to redirect control to other pages within the web application.

Syntax: <c:redirect url="value" [context="context"] />

10).  <c:param>

This tag is used to add request parameters to a URL. It is also used as a nested tag, within the <c:import>, <c:url> and <c:rediret> tags.

Syntax: <:param name = parameterName" value = "parameterValue" />

11).  <c:forEachToken>

This tag when provided with delimiters can be used to iterate over tokens. Its functionality is like that of StringTokenizer.

Syntax: <c:forTokens items = "tokenString" delims="delimiter"

            [var="variableName"] [varStatus="variableStatusName"] [begin="start"  [end="end"]  [step="step"]> ........ body content..</c:forTokens>