JSP Standard Tag Library (JSTL) Overview and Original understanding

JSP Standard Tag Library (JSTL) Overview and Original understanding JSP Standard Tag Library (JSTL) is an extension function of the Java server page (JSP) technology, which aims to simplify and enhance the development of the JSP page.It provides a set of reusable labels that enable developers to perform common control processes, iteration, conditional judgment, formatting and internationalization on the JSP page.Using JSTL can improve the readability, maintenance, and reuse of the JSP code. JSTL consists of two parts: core label library and XML tag library.The core label library provides labels to handle common programming tasks, such as loop iteration, conditional judgment and formatting data.The XML label library is used to process XML documents and data. The following is an example of the JSTL core label library, which shows how to use the Foreach label to iterate a Java collection and display the elements in the set in the JSP page: <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %> <c:forEach var="item" items="${myCollection}"> <li>${item}</li> </c:forEach> In the above code, the `<C: Foreach>` label traversed a collection called `mycollection`, and each element is put into a variable named` item`.Then, inside the `li>` label, use the EL expression in the form of {item} `to display the collection element. The principle of JSTL is implemented through the custom label of the JSP page.When the JSP page contains the JSTL label, the JSP container resolves it as a Java code and executes when the page is requested.In this way, developers can use simple and intuitive labels to complete complex programming tasks without having to directly write a large number of Java code. To use JSTL in the project, you need to add jstl -related JAR files to the project path of the project, and import related label libraries in the JSP page.By using the label on the JSP page, the function provided by JSTL can be directly called. In summary, JSTL is a label library that provides common functions for JSP pages.It simplifies the development and maintenance of the JSP page, and improves the readability and reuse of the code.By using JSTL, developers can focus more on page logic and display effects without having to spend too much energy on the underlying Java code writing.