JSP Standard Tag Library (JSTL) The principle inquiry and practice in the Java class library should be
JSP Standard Tag Library (JSTL) The principle inquiry and practice in the Java class library should be
Overview:
JSP Standard Tag Library (JSTL) is an extension of the Java Servlet API, which aims to provide more flexible and reusable labels and functions for the JSP page.This article will explore the principles of JSTL in the Java library and provide practical application examples.
JSTL principle:
JSTL provides additional functions by using a custom tag on the JSP page.These tags can be introduced into the JSP page through the library provided by JSTL and perform the corresponding functions through the label in the label library.The JSTL tag library includes multiple different tags, such as the core tag library, the formatting tag library, XML tag library, etc.
In order to use JSTL, you need to introduce the corresponding label library in the JSP page.This can be implemented by adding the following code to the top of the page:
jsp
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
After introducing the label library, you can use the JSTL label on the JSP page to execute the required functions.For example, using the <C: Foreach> label in the core label library to traverse a collection:
jsp
<c:forEach var="item" items="${collection}">
${item}
</c:forEach>
The above code will be traveled through a collection of "Collection" and uses the variable "item" to represent the elements in each set.In the cycle, the value of each element can be accessed through "$ {item}".
Practice application:
The following is an actual application example, which shows the use of JSTL in the Java class library.Suppose we have a student class, which contains students' names and age information.We hope to display a student table on the JSP page to list the names and age of each student.
First, create a Student class that represents a student in the Java class:
public class Student {
private String name;
private int age;
public Student(String name, int age) {
this.name = name;
this.age = age;
}
public String getName() {
return name;
}
public int getAge() {
return age;
}
}
Then, the JSTL tag library is introduced on the JSP page, and the <C: Foreach> tag is used to traverse the student list and display the form:
jsp
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<html>
<head>
<Title> Student Form </Title>
</head>
<body>
<table>
<tr>
<TH> Name </th>
<TH> Age </th>
</tr>
<c:forEach var="student" items="${studentList}">
<tr>
<td>${student.name}</td>
<td>${student.age}</td>
</tr>
</c:forEach>
</table>
</body>
</html>
In the above examples, the JSTL tag library is introduced first, and then the <C: Foreach> tag is used in the table to traverse the list of students named "StudentList".In the cycle, you can use "$ {Student.name}" and "$ {Student.age}" to access the names and age of each student object.
Through the above practice example, you can see the use of JSTL standard label library and application scenarios.The main advantage of JSTL is that it provides a set of powerful and reusable labels that can simplify the development of JSP pages and improve the readability and maintenance of code.
