JSP Standard Tag Library Tutorial

Welcome to DataFlair JST Tutorial. This article discusses the JSTL, i.e., Standard Tag Library of JSP. It discusses the tags and functions present in it in detail. So let’s see JSP Standard tag Library in detail.

JSP Standard Tag Library Introduction

There are different tags in JSP. The Standard Tag Library of JSP, known as JSTL, is a collection of JSP tags. JSTL supports tasks that are common or structural in nature. They are iteration and conditionals, tags that stimulate internationalization tags, XML documents, and SQL tags. It integrates custom tags too.

To use them, we need to firstly install them. So let’s learn JSTL Installation.

How to Install JSTL Library

For apache tomcat-users, the following is the approach for JSTL Installation:

• Download and unpack the compressed file of Apache Standard Taglib.
• Copy the jar files into the lib folder to the destination: webapps\ROOT\WEB-INF\lib directory
  <taglib> directive include these tags.

JSTL tags and their classification

JSTL is a standard library tag used to implement functionalities in JSP programs. They classify under tag library groups based on their functionality. They are:

• Core Tags
• Formatting tags
• SQL tags
• XML tags
• JSTL Functions

JSTL Core Tags

They are the most important and most used tags among the JSTL tags.
Syntax:

<%@ taglib prefix = "c" uri = "http://www.mysun.com/jsp/jstl/core" %>

Core tags in JSTL are as follows:

Formatting Tags in JSP

Formatting tags format the display of the date, time, text, especially for international websites. Through the following syntax, you can include the formatting library in JSP
Syntax: 

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

JSTL SQL Tags

These JSTL tags will help in interacting with databases like MySQL, Oracle, etc. The syntax to include SQL library is as follows:
Syntax:

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

JSTL SQL tags are as follows:

JSTL XML Tags

These XML tags provide an easy way to manipulate XML documents. XML tag library has custom tags to interact with XML data. These interactions are transforming, controlling flow, parsing the XML data.
Syntax:

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

XML JSTL Tags are as follows:

JSTL Functions

JSTL has a number of standard functions. They do string manipulation. Syntax to include Functions library of JSTL in JSP is as follows −
Syntax:

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

Various JSTL Functions are as follows:

Features of JSTL

The tags simplify the task to create Web pages, especially for designers. They provide the following features.

• JSTL core tags provide iterative tags. It supports the processing of the URL’s resources in a JSP page to locate URLs.
• XML tag library helps in manipulating the XML documents.
• They provide conditional and iteration processing on XML documents.
• It supports internationalized web applications so that they are globally available for use. It makes the application localized so that it is reliable and effective. Internationalized libraries help it adapt to various locales.
• JSTL provides functions from the functions tag library to perform actions like checking for substring passed as the parameter in the function is present in a string, the number of characters in a string, etc.
• It provides the SQL tag library to retrieve and connect with the relational databases using these SQL tags.

Advantages of JSTL

1. Standard Tag: The code is easy to understand for the developers as it provides the portable functionality for a JSP page.
2. Clean code: JSTL makes the code clean, as the scriptlet code can be confusing.
3. Easy for humans to read: As the code is in XML format, it is neat, clean, and easier to understand.
4. Better off for computers to understand: Parsing of the JSTL becomes easier for the HTML as the JSTL code is written in the XML format.
5. Javabeans Introspection Support: JSTL simplifies the use of bean objects, unlike JSP.

Example of JSTL

In this example, we have printed all the numbers from 1 to 5.

<%@ taglib uri="http://java.sun.com/jstl/core" prefix="c" %>
<html>
<head>
<title> Numbers</title>
</head>

  <body>
  <c:forEach var="i" begin="1" end="5">
  	Value<c:out value="${i}" />

  	<br />
  </c:forEach>
  </body>
</html>

Explanation: An iteration tag for each. It takes a beginning and an ending value and iterates over.

Output: The output will be as follows:

Value1
Value2
Value3
Value4
Value5

Conclusion

This article consists of a detailed description of the standard tag library for JSP, known as JSTL. We also saw the tags in this library, as well as the functions present in it. Then we saw the way to install it. Finally, we also pondered upon some of its advantages and features.