JSTL Tutorial

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JSTL Tutorial

JSTL tutorial explains you the various JSP tags that can be used in the JSP pages.

JSTL tutorial explains you the various JSP tags that can be used in the JSP pages.

JSTL Tutorial

In this section we will read about JSTL. You will read about how it is implemented and used in JSP pages.

JSTL also known as Java Standard Tag Library is a collection of various tags for performing tasks like iteration, conditional checks, data formatting, localization etc. These tags are gathered as to perform the tasks that are commonly used in JSP applications. JSTL provides the feature for integrating the custom tags with JSTL tags. JSTL tags are classified on their use/purpose. These are as follows :

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

To use JSTL you would have to first download the JSTL JARs. Then it should be kept inside the lib folder in the web server/application server.

JSTL Core Tags

JSTL Core Tags are used for manipulating with the data in JSP pages. Such as, iterating on data collection, set an output, apply the conditional statements, set the parameter etc.

To use the JSTL Core Tags you would have to use the following taglib

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

Followings are the commonly used tags of JSTL core tag library that are used in the JSP pages :

  • <c:out > : This tag is used for displaying the output. This tag is like the <%= %> expressions in JSP for showing the output.
  • <c:if> : This tag is like the "if" conditional statement in Java which evaluates its body when the given condition becomes true.
  • <c:choose> : This tag is the super tag of <c:when> tag. choose specifies the mutually exclusive conditional operations.
  • <c:when> : This tag is the sub tag of <c:choose> tag. This tag evaluates its body when the given condition becomes true.
  • <c:otherwise > : This tag is the sub tag of <c:choose> tag. This tag evaluates its body when all the condition given earlier becomes false.
  • <c:import> : This tag is used to include the functionality of the specified URL as an absolute or relative and may put it into either a page, a string var, or a Reader.
  • <c:forEach > : This tag is used to iterate over the collection of data.
  • <c:url> : This tag is used for URL rewriting.
  • <c:param> : This tag is used to provide the additional parameter to the URL.
  • <c:redirect > : This tag is used to redirect to a specified URL location.
  • <c:set> : This tag is used to set the outcome after evaluation of an expression.
  • <c:remove> : This tag is used to remove a variable specified in the particular scope.
  • <c:catch> : This tag is used to catch the throwable exception.
  • <c:forTokens> : This tag is used for traversing over tokens for the given delimeters.

JSTL Formatting Tags

JSTL Formatting Tags are useful for the internationalization. Internationalization means formatting the text, date, time, numbers, etc. according to their localization. The JSTL format tag library provides many of the tags that are helpful in creation of internationalized websites.

To use the JSTL Formatting Tags you would have to use the following taglib :

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

Followings are the commonly used tags of JSTL format tag library :

  • <fmt:formatNumber> : This tag is used to format a numeric value in a specified format.
  • <fmt:parseNumber> : This tag is used to parse the number represented as string, currency, or percentage.
  • <fmt:formatDate> : This tag is used to format a date/time into the specified format.
  • <fmt:parseDate> : This tag is used to parse the date represented as string.
  • <fmt:bundle> : This tag is used to load the resource bundle.
  • <fmt:setLocale> : This tag is used to set the specified locale.
  • <fmt:setBundle> : This tag is used to load the resource bundle and keep it into the scope variable.
  • <fmt:message> : This tag is used to format the message as an internationalized message.
  • <fmt:timeZone> : This tag is used to format the time zone.
  • <fmt:setTimeZone> : This tag is used to specifies the time zone.
  • <fmt:requestEncoding> : This tag is used to specifies the request character encoding.

JSTL SQL Tags

JSTL SQL Tags are useful to manipulate the database data in the JSP page. These tags helps in to interact with the Database for example, MySQL, Oracle, etc.

To use the JSTL SQL Tags you would have to use the following taglib :

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

Followings are the commonly used tags of JSTL sql tag library :

  • <sql:setDataSource> : This tag is used for creating data source.
  • <sql:query> : This tag is used to execute the sql query defined inside its body or by the sql attribute.
  • <sql:update> : This tag is used to execute the sql update defined inside its body or by the sql attribute.
  • <sql:param> : This tag is used to add a parameter to the sql statement to the given value.
  • <sql:dateParam> : This tag is used to add a parameter to the sql statement to the given java.util.Date value.
  • <sql:transaction > : This tag is used to execute all statements in one transaction.

JSTL XML Tags

JSTL XML Tags are useful for manipulating the XML documents. This tag library allows the developer to interact with the XML data on JSP page for example, XML parsing, transform XML data, flow control based on XPath expressions.

To use the JSTL XML Tags you would have to use the following taglib :

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

When you want to work with the JSTL XML Tag libraries you would also have to keep the two additional XML and XPath related libraries inside the lib folder of the Tomcat Installation Directory.

Followings are the commonly used tags of JSTL XML tag library :

  • <x:out> : This tag is like the <%=..... %> XPath expression.
  • <x:parse> : This tag is used to parse the XML data.
  • <x:set> : This tag is used to set a variables value of XPath expression.
  • <x:if> : This tag is processes its body when the XPath expression is true.
  • <x:forEach> : This tag is used to traverse over the nodes in an XML document.
  • <x:choose> : This tag is the super tag of <x:when> tag. choose specifies the mutually exclusive conditional operations
  • <x:when> : This tag is the sub tag of <x:choose> tag. This tag evaluates its body when the given condition becomes true.
  • <x:otherwise> : This tag is the sub tag of <x:choose> tag. This tag evaluates its body when all the condition given earlier becomes false.
  • <x:transform> : This tag is used to transform XSL data on XML document.
  • <x : param> : This tag is used to add the parameter in XSL style sheet. This tag is used with transform tag.

JSTL Functions

JSTL Functions library is the collection of functions that are provided to use. One can use these standard functions on the JSP pages while coding. Most of these provided functions are commonly used for string manipulation.

To use the JSTL functions you would have to use the following taglib :

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

Followings are the commonly used functions of JSTL functions :

  • fn:contains() : This method is used to check whether the specified string is contained by the existing string or not. This method is case sensitive.
  • fn:containsIgnoreCase() : This method is used to check whether the specified string is contained by the existing string or not. This method is case insensitive.
  • fn:endsWith() : This method is used to check whether the specified string is ends with the specified suffix or not.
  • fn:escapeXml() : This method is used to escape the XML characters/tags.
  • fn:indexOf() : This method is used to get the index of the first occurrence of the string within a string.
  • fn:join() : This method is used to join the elements of array into a string.
  • fn:length() : This method is used to return the size of the string.
  • fn:replace() : This method is used to replace an existing string with the new one string.
  • fn:split() : This method is used to split a string and returns an array of substrings.
  • fn:startsWith() : This method is used to check whether the specified string is started with the given prefix or not.
  • fn:substring() : This method is used to find the substring of specified string.
  • fn:substringAfter() : This method is used to find the substring after a given substring.
  • fn:substringBefore() : This method is used to find the substring before a given substring.
  • fn:toLowerCase() : This method is used to convert the upper case string to lower case.
  • fn:toUpperCase() : This method is used to convert the lower case string to upper case.
  • fn:trim() : This method is used to remove the white space from the both side of string.

To read more in detail about JSTL and Examples you may go through the following link : http://www.roseindia.net/jstl/index.shtml

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