Reference - JSP JSTL
JSTL
JavaServer Pages Standard Tag Library
Is a collection of useful JSP tags which encapsulates the core functionality common to many JSP applications
Has support for common, structural tasks such as iteration and conditionals, tags for manipulating XML documents, internationalization tags, ans SQL tags, It also provide a framework for integrating the existing custom tags with the JSTL tags
Install
Download the binary distribution from Apache Standard Taglib
Copy the JAR files in the distribution’s ‘lib’ directory to application’s webapps/ROOT/WEB-INF
To use libraries, must include a <taglib> directive at the top of each JSP that uses the library
Core Tag
Are the most commonly used JSTL tags
<%@ taglib prefix = “c” uri = http://java.sun.com/jsp/jstl/core %>
| Tag | Description |
|---|---|
<c:out> |
Like <%= …>, but for expressions |
<c:set> |
Sets the result of an expression evaluation in a ‘scope’ |
<c:remove> |
Removes a scoped variable(from a particular scope, if specified) |
<c:catch> |
Catches any Throwable that occurs in its body and optionally exposes it |
<c:if> |
Simple conditional tag which evaluates its body if the supplied condition is true |
<c:choose> |
Simple conditional tag that establishes a context for mutually exclusive conditional operations, marked by <when> and <otherwise> |
<c:when> |
Subtag of <choose> that includes its body if its condition evaluates to ‘true’ |
<c:otherwise> |
Subtag of <choose> that follows the <when> tags and runs only if all of the prior conditions evaluated to ‘false’ |
<c:import> |
Retrieves an absolute or relative URL and exposes its contents to either the page, a String in ‘var ’, or a Reader in ‘varReader’ |
<c:forEach> |
The basic iteration tag, accepting many different collection types and supporting subsetting and other functionality |
<c:forTokens> |
Iterates over tokens, separated by the supplied delimeters |
<c:param> |
Adds a parameter to a containing ‘import’ tag’s URL |
<c:redirect> |
Redirects to a new URL |
<c:url> |
Creates a URL with optional query parameters |
Formatting Tag
Are used to format and display text, the date, the time, and numbers for internationalized Websites
<%@ taglib prefix = “fmt” uri = “http://java.sun.com/jsp/jstl/fmt %>
| Tag | Description |
|---|---|
<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 |
SQL Tag
Provides tags for interacting with relational databases (RDBMSs) such as Oracle, mySQL, or MS SQL Server
<%@ taglib prefix = “sql” uri = “http://java.sun.com/jsp/jstl/sql”>
| Tag | Description |
|---|---|
<sql:setDataSource> |
Creates a simple DataSource suitable only for prototyping |
<sql:query> |
Exceutes 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 statement as one transaction |
XML Tag
Provides a JSP-centric way of creating and manipulating the XML documents
Library has custom tags for interacting with the XML data, this includes parsing the XML, transforming the XML data, and the flow control based on the XPath expressions
<%@ taglib prefix= “x” uri = “http://java.sun.com/jsp/jstl/xml”>
Before use tags, will need to copy the XercesImpl.jar and xalen.jar into `Tomcat Installation Directory/lib-
| Tag | Description |
|---|---|
<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 <when> and <otherwise> tags |
<x:when> |
Subtag of <choose> that includes its body if its expression evaluates to ‘true’ |
<x:otherwise> |
Subtag of <choose> that follows the <when> 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
<%@ taglib prefix = “fn” uri = http://java.sun.com/jsp/jstl/functions %>
| Function | Description |
|---|---|
| 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:substirngBefore() | 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 |