Jakarta Standard Tag Library API instance tutorial (Example Tutorial)

Jakarta Standard Tag Library (JSTL) API is a set of labels and functions used in Java Web applications. The purpose is to simplify and accelerate the development process.In this tutorial, we will introduce JSTL API and its usage, and provide some Java code examples to help you better understand. Introduction to JSTL Jstl is designed to simplify the Java code on the JSP (Java Server Pages) page.It provides a set of labels and functions that can be used to perform common tasks, such as conditional judgment, cycle, formatting date and value.By using JSTL, we can reduce the number of Java code on the JSP page, making the code clearer and simpler. Second, the installation and configuration of JSTL To start using the JSTL API, you need to add the dependencies of the JSTL library to the project.You can add dependencies through Maven or manually download the jstl jar file.Once you add dependencies, you can use JSTL tags and functions on the JSP page. Third, JSTL commonly used tags and functions 1. Core tag library The core label library provides some basic labels for circulation, conditional judgment, variable settings and other tasks.Here are some commonly used core label library examples: <c:forEach var="item" items="${items}"> <tr> <td>${item.name}</td> <td>${item.price}</td> </tr> </c:forEach> 2. Formatting tag library The formatting label library allows formatting data such as dates and numbers into specific string representations.The following is an example of a date formatting: <fmt:formatDate value="${date}" pattern="yyyy-MM-dd" var="formattedDate" /> <p>Formatted date: ${formattedDate}</p> Fourth, JSTL use examples In order to explain the use of JSTL, the following is a simple example: Assuming we have a list of product information, we want to use JSTL to display the list on the JSP page. 1. Create a product class that includes the name and price attribute of the product. public class Product { private String name; private double price; // omit the creation function and getter/setter method } 2. Create a List containing product information in Servlet and pass it to the JSP page. List<Product> products = new ArrayList<>(); products.add(new Product("Product A", 10.0)); products.add(new Product("Product B", 20.0)); products.add(new Product("Product C", 30.0)); request.setAttribute("products", products); request.getRequestDispatcher("products.jsp").forward(request, response); 3. In the products.jsp file, use the JSTL tag library to display the product list. <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %> <table> <thead> <tr> <th>Name</th> <th>Price</th> </tr> </thead> <tbody> <c:forEach var="product" items="${products}"> <tr> <td>${product.name}</td> <td>${product.price}</td> </tr> </c:forEach> </tbody> </table> The above example demonstrates how to use the JSTL label library on the JSP page to iterate the product list and display the name and price of each product in the table. Summarize: This tutorial introduces the basic concepts and usage of Jakarta Standard Tag Library (JSTL) API.By using JSTL, we can avoid writing a large number of java code on the JSP page, so that the code is more concise and clear.I hope this tutorial will be helpful for developers who learn and use JSTL.