Use Jakarta Standard Tag Library API
Use Jakarta Standard Tag Library (JSTL) API to develop web applications
Introduction:
JSTL is a standard labeling library for developing the Javaweb application. It provides many labels for handling common tasks, such as iteration, conditions, formatting.This article will introduce you how to use Jakarta Standard Tag Library API to develop Web applications and provide corresponding Java code examples.
Step 1: Configure item
First, you need to include the JSTL library file in the project path.You can add dependencies by downloading Jakarta standard label database and adding it to the project, or through building tools such as Maven or Gradle.Make sure to configure the reference to the jstl tag library in the web.xml file of the project.
Step 2: Introduce JSTL Tag Library
In your JSP page, you need to introduce the JSTL label library to use the label.You can import the JSTL tag library through the following ways:
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
Step 3: Use the JSTL tag
Next, you can use JSTL tags on the JSP page to complete various tasks.Here are some commonly used JSTL label examples:
1. iteration label:
<c:forEach var="item" items="${items}">
${item}
</c:forEach>
This example will traverse the ITEMS collection and display each element one by one.
2. Condition label:
<c:if test="${condition}">
The condition is the content displayed when the real time
</c:if>
This example will determine whether the content is displayed based on the value of the Condition variable.
3. Formatting tags:
<fmt:formatNumber value="${number}" pattern="#,###" />
This example will format the value of the NUMBER variable and use the specified mode to display.
Step 4: Writing business logic
In addition to using the JSTL label on the JSP page, you can also use the JSTL API in the Java code to process more complex business logic.The following is an example:
@Controller
public class MyController {
@RequestMapping("/hello")
public String hello(Model model) {
List<String> items = Arrays.asList("item1", "item2", "item3");
model.addAttribute("items", items);
return "hello";
}
}
This example demonstrates how to pass the Items list to the JSP page in the controller.
Step 5: Create the JSP page
Finally, you need to create a JSP page to display your data and JSTL tags.The following is an example:
<html>
<head>
<title>Hello JSTL</title>
</head>
<body>
<ul>
<c:forEach var="item" items="${items}">
<li>${item}</li>
</c:forEach>
</ul>
</body>
</html>
This example will display the value in the Items list on the page.
Summarize:
By using Jakarta Standard Tag Library API, you can easily develop Web applications with rich functions and use the JSTL tag library to simplify the processing of common tasks.In this article, we introduce how to configure projects, introduce JSTL tag libraries, use JSTL tags and write business logic, and provide corresponding Java code examples.I hope this article can help you quickly use the JSTL API to develop Web applications.
Java code example:
