Jakarta Standard Tag Library API Developer Document (Developer Documentation)

Jakarta Standard Tag Library (JSTL) API developer documentation Introduction: Jakarta Standard Tag Library (JSTL) is a standard extension library developed by the Java Web application. It provides a set of simple and easy -to -use labels and functions for common logic processing and page display on the JSP page.This document will introduce the use of Jakarta standard label library API and Java code example. 1. Installation and configuration JSTL library: First of all, you need to download the JAR file of the JSTL library and add it to the class path of your Java Web application.You can download the latest version of the JSTL library from Apache's official website or Maven warehouse. Then, add the following configuration information to the web.xml file of your web application to enable the use of the JSTL library: <web-app xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" version="2.5"> <jsp-config> <taglib> <taglib-uri>http://java.sun.com/jsp/jstl/core</taglib-uri> <taglib-location>/WEB-INF/lib/jstl-core.jar</taglib-location> </taglib> <taglib> <taglib-uri>http://java.sun.com/jsp/jstl/fmt</taglib-uri> <taglib-location>/WEB-INF/lib/jstl-fmt.jar</taglib-location> </taglib> </jsp-config> </web-app> 2. Use JSTL tags: The JSTL library provides multiple label libraries for different types of operations on the JSP page.Here are some commonly used JSTL tags and their example usage: -` <C: Foreach> `: Used to recycling the collection or array. jsp <c:forEach var="item" items="${myList}"> <c:out value="${item}"/> </c:forEach> -` <C: if> `: For conditional judgment and control process. jsp <c:if test="${myVar > 10}"> <p> greater than 10 </p> </c:if> -` <C: set> `: Used to set variables. jsp <c:set var="myVar" value="10"/> -` <C: Choose> `and` <C: WHEN> `: Used for multi -conditional judgment. jsp <c:choose> <c:when test="${myVar == 10}"> <p> equal to 10 </p> </c:when> <c:when test="${myVar == 20}"> <p> equal 20 </p> </c:when> <c:otherwise> <p> Other situations </p> </c:otherwise> </c:choose> 3. Use the JSTL function: The JSTL library also provides some useful functions that can be used in the JSP page.Here are some commonly used JSTL functions and its example usage: -` Fn: LENGTH () `: Calculate the length of the set or string. jsp <p> A collection of <c: Out Value = "$ {fn: length (mylist)}"/>.</p> -` Fn: Touppercase () `: Convert the string to uppercase. jsp <p> Capital form: $ {fn: Touppercase (mystring)} </p> -` Fn: Substring () `: Get the sub -string of the string. jsp <p> child skewer: $ {fn: substring (Mystring, 0, 5)} </p> -` fn: contains () `: Check whether the string contains a specified sub -string. jsp <c:if test="${fn:contains(myString, 'example')}"> <p> Including specified sub -string </p> </c:if> The above is just a small part of the label and function provided by the JSTL library. You can find more detailed explanations and examples in the official document. Summarize: Through this document, you understand how to install and configure the JAKARTA standard tag library (JSTL) API, and learn how to use some common JSTL tags and functions and Java code examples.The JSTL library provides convenience for the development of Java Web, which can simplify the logic processing and page display of the JSP page to improve development efficiency.I hope this article will help you when using the JSTL library!