Jakarta Standard Tag Library API new feature introduction
Jakarta Standard Tag Library (JSTL) API new feature introduction introduction
Overview:
Jakarta Standard Tag Library (JSTL) is a Java standard label library developed by Apache. It provides a lot of useful labels and functions for the JSP page, enabling developers to process and display data easier.This article will introduce the new features in the JSTL API to help developers better use the JSTL library to develop the Java web application.
1. Core tag library
The core label library of JSTL API provides a set of powerful labels for control processes, conditional judgment, circular iteration and output.Here are some new core tags in the JSTL 1.2 version:
- <C: Set> Tags: Used to set a variable that can be reused on the page.
- <C: Remove> Tags: Used to remove the specified variable.
- <C: Catch> Tags: It is used to capture abnormalities and perform specific operations.
- <C: Import> Tags: content used to import other pages.
- <C: Redirect> Tags: Used to redirect to other pages.
The following is an example of using the JSTL core label library:
jsp
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<!DOCTYPE html>
<html>
<head>
<title>JSTL Core Tags Example</title>
</head>
<body>
<c:set var="name" value="John Doe" />
Hello, <c:out value="${name}" />!
</body>
</html>
2. Formatting tag library
The formatting tag library of JSTL API provides a set of labels for formatting dates, numbers and messages, and international support.The new features in JSTL 1.2 include::
- <FMT: Parsenumber> Tags: For analytical numbers.
- <fmt: Formatnumber> Tags: For formatting numbers.
- <FMT: PAREDATE> Tags: Utilized date.
- <FMT: Formatdate> Tags: For the formatting date.
- <fmt: Message> Tags: Used to obtain localization.
The following is an example of using JSTL formatting label library:
jsp
<%@ taglib prefix="fmt" uri="http://java.sun.com/jsp/jstl/fmt" %>
<!DOCTYPE html>
<html>
<head>
<title>JSTL Formatting Tags Example</title>
</head>
<body>
<fmt:setLocale value="en_US" />
<fmt:parseNumber var="price" type="number" value="1000" />
Formatted Price: <fmt:formatNumber value="${price}" type="currency" />
</body>
</html>
3. SQL Tag Library (SQL Tag Library)
The SQL label library of JSTL API provides a set of labels for executing SQL queries.These tags can easily retrieve data from the database and display on the JSP page.The following is the new SQL tag in JSTL 1.2:
- <SQL: Update> Tags: Used to execute SQL update statements.
- <SQL: Transaction> Tags: Used to create database transactions.
- <SQL: Query> Tags: Used to execute SQL query statements.
- <SQL: Param> Tags: For setting SQL query parameters.
The following is an example of using the JSTL SQL tag library:
jsp
<%@ taglib prefix="sql" uri="http://java.sun.com/jsp/jstl/sql" %>
<!DOCTYPE html>
<html>
<head>
<title>JSTL SQL Tags Example</title>
</head>
<body>
<sql:setDataSource
var="db"
driver="com.mysql.jdbc.Driver"
url="jdbc:mysql://localhost/dbname"
user="username"
password="password" />
<sql:query dataSource="${db}" var="result">
SELECT * FROM users
</sql:query>
<table>
<c:forEach var="row" items="${result.rows}">
<tr>
<td>${row.id}</td>
<td>${row.name}</td>
<td>${row.email}</td>
</tr>
</c:forEach>
</table>
</body>
</html>
Summarize:
This article introduces some new features in Jakarta Standard Tag Library (JSTL) API.Using JSTL, developers can easily process and display data, save code amounts, and improve the development efficiency of the Java Web application.Through the core label database, formatting label library and SQL label library, developers can better use the JSTL library to complete various tasks.In actual development, you can choose the appropriate JSTL tag library according to the needs to quickly build a powerful web application.
