JSTL-Tutorials ❤️

This is my JSTL Tutorial which is about JSTL (JSP Tag Libraries) that gives you a clear understanding about all the JSTL tags and their functionalities with practical code implementations for each tags.

Introduction 👋

The JavaServer Pages Standard Tag Library (JSTL) is a collection of useful JSP tags which encapsulates the core functionality common to many JSP applications.
JSTL has support for common, structural tasks such as iteration and conditionals, tags for manipulating XML documents, internationalization tags, and SQL tags.
It also provides a framework for integrating the existing custom tags with the JSTL tags.

Install JSTL Library 📫

To begin working with JSP tages you need to first install the JSTL library.
If you are using the Apache Tomcat container, then follow these two steps −

Step 1 :

- Download the binary distribution from Apache Standard Taglib and unpack the compressed file.

Download JAR Files here : JSTL JAR 1.2

Step 2 :

− To use the Standard Taglib from its Jakarta Taglibs distribution, simply copy the JAR files in the distribution's 'lib' directory to your application's webapps\ROOT\WEB-INF\lib directory.

[Note: If you are creating a Maven Project, use the following dependency to add JSTL Jar files]

  <dependency>
      <groupId>jstl</groupId>
      <artifactId>jstl</artifactId>
      <version>1.2</version>
  </dependency>
  <dependency>
      <groupId>taglibs</groupId>
      <artifactId>standard</artifactId>
      <version>1.1.2</version>
  </dependency>

To use any of the libraries, you must include a directive at the top of each JSP that uses the library.

Advantage of JSTL 😄

Fast Development - JSTL provides many tags that simplify the JSP
Code Reusability - We can use the JSTL tags on various pages
No need to use scriptlet tag - It avoids the use of scriptlet tag

JSTL Tags ✔️

JSTL Core Tags:

JSTL Core tags provide support for iteration, conditional logic, catch exception, url, forward or redirect response etc.
To use JSTL core tags, we should include it in the JSP page like below.

<%@ taglib uri="https://java.sun.com/jsp/jstl/core" prefix="c" %>

JSTL Formatting and Localisation Tags:

JSTL Formatting tags are provided for formatting of Numbers, Dates and i18n support through locales and resource bundles.
We can include these jstl tags in JSP with below syntax:

<%@ taglib uri="https://java.sun.com/jsp/jstl/fmt" prefix="fmt" %>

JSTL SQL Tags:

JSTL SQL Tags provide support for interaction with relational databases such as Oracle, MySql etc.
Using JSTL SQL tags we can run database queries, we include these JSTL tags in JSP with below syntax:

<%@ taglib uri="https://java.sun.com/jsp/jstl/sql" prefix="sql" %>

JSTL XML Tags:

JSTL XML tags are used to work with XML documents such as parsing XML, transforming XML data and XPath expressions evaluation. -Syntax to include JSTL XML tags in JSP page is:

<%@ taglib uri="https://java.sun.com/jsp/jstl/xml" prefix="x" %>

STL Functions Tags:

JSTL tags provide a number of functions that we can use to perform common operation, most of them are for String manipulation such as String Concatenation, Split String etc.
Syntax to include JSTL functions in JSP page is:

<%@ taglib uri="https://java.sun.com/jsp/jstl/functions" prefix="fn" %>

JSTL Core Tags ⌚

<c:out>

To write something in JSP page, we can use EL also with this tag

<c:import>

Same as jsp:include or include directive

<c:redirect>

redirect request to another resource

<c:set>

To set the variable value in given scope.

<c:remove>

To remove the variable from given scope

<c:catch>

To catch the exception and wrap it into an object.

<c:if>

Simple conditional logic, used with EL and we can use it to process the exception from <c:catch>

<c:choose>

Simple conditional tag that establishes a context for mutually exclusive conditional operations, marked by <c:when> and <c:otherwise>

<c:when>

Subtag of <c:choose> that includes its body if its condition evalutes to ‘true’.

<c:otherwise>

Subtag of <c:choose> that includes its body if its condition evalutes to ‘false’.

<c:forEach>

for iteration over a collection

<c:forTokens>

for iteration over tokens separated by a delimiter.

<c:param>

used with <c:import> to pass parameters

<c:url>

To create a URL with optional query string parameters

JSTL Formatting Tags ⌛

<fmt:formatNumber>

To render numerical value with specific precision or format.

<fmt:parseNumber>

Parses the string representation of a number, currency, or percentage.

<fmt:formatDate>

Formats a date and/or time using the supplied styles and pattern.

<fmt:parseDate>

Parses the string representation of a date and/or time

<fmt:bundle>

Loads a resource bundle to be used by its tag body.

<fmt:setLocale>

Stores the given locale in the locale configuration variable.

<fmt:setBundle>

Loads a resource bundle and stores it in the named scoped variable or the bundle configuration variable.

<fmt:timeZone>

Specifies the time zone for any time formatting or parsing actions nested in its body.

<fmt:setTimeZone>

Stores the given time zone in the time zone configuration variable

<fmt:message>

Displays an internationalized message.

<fmt:requestEncoding>

Sets the request character encoding

JSTL SQL Tags ⏩

<sql:setDataSource>

Creates a simple DataSource suitable only for prototyping

<sql:query>

Executes the SQL query defined in its body or through the sql attribute.

<sql:update>

Executes the SQL update defined in its body or through the sql attribute.

<sql:param>

Sets a parameter in an SQL statement to the specified value.

<sql:dateParam>

Sets a parameter in an SQL statement to the specified java.util.Date value.

<sql:transaction>

Provides nested database action elements with a shared Connection, set up to execute all statements as one transaction.

JSTL XML tags 📌

<x:out>

Like <%= ... >, but for XPath expressions.

<x:parse>

Used to parse the XML data specified either via an attribute or in the tag body.

<x:set >

Sets a variable to the value of an XPath expression.

<x:if >

Evaluates a test XPath expression and if it is true, it processes its body. If the test condition is false, the body is ignored.

<x:forEach>

To loop over nodes in an XML document.

<x:choose>

Simple conditional tag that establishes a context for mutually exclusive conditional operations, marked by and tags.

<x:when >

Subtag of that includes its body if its expression evalutes to 'true'.

<x:otherwise >

Subtag of that follows the tags and runs only if all of the prior conditions evaluates to 'false'.

<x:transform >

Applies an XSL transformation on a XML document

<x:param >

Used along with the transform tag to set a parameter in the XSLT stylesheet

JSTL Function Tags ✔️

<fn:contains()>

Tests if an input string contains the specified substring.

<fn:containsIgnoreCase()>

Tests if an input string contains the specified substring in a case insensitive way.

<fn:endsWith()>

Tests if an input string ends with the specified suffix.

<fn:escapeXml()>

Escapes characters that can be interpreted as XML markup.

<fn:indexOf()>

Returns the index withing a string of the first occurrence of a specified substring.

<fn:join()>

Joins all elements of an array into a string.

<fn:length()>

Returns the number of items in a collection, or the number of characters in a string.

<fn:replace()>

Returns a string resulting from replacing in an input string all occurrences with a given string.

<fn:split()>

Splits a string into an array of substrings.

<fn:startsWith()>

Tests if an input string starts with the specified prefix.

<fn:substring()>

Returns a subset of a string.

<fn:substringAfter()>

Returns a subset of a string following a specific substring.

<fn:substringBefore()>

Returns a subset of a string before a specific substring.

<fn:toLowerCase()>

Converts all of the characters of a string to lower case.

<fn:toUpperCase()>

Converts all of the characters of a string to upper case.

<fn:trim()>

Removes white spaces from both ends of a string.

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