The <c:set> tag is used for variable creation and assignment in JSP pages. In this article, we will delve into the JSTL Core <c:set> tag, provide code samples, and illustrate the expected outputs. It is used to set the result of an expression evaluated in a “scope”.
Prerequisite of the topic
- Good understanding of Java EE web project developments like setting up a servlet or a JSP page with the help of any IDE
- Any IDE with support for Java EE development.
- An installation of Apache Tomcat web server or any other server that supports running Java-based web applications like GlassFish, Websphere, etc.
Syntax
<c:set var="string" value="string" target="string" property="string> scope="string"/>
Attributes of <c:set>
|
Name |
Description |
Type |
Required |
|---|---|---|---|
|
var |
Name of the variable to store the value |
String |
False |
|
value |
Expression to be evaluated |
String |
False |
|
target |
Target Object whose object is set. Must evaluate to a JavaBean with setter or java.util.Map Object |
String |
False |
|
property |
Name of the property to be set in the target object. |
String |
False |
|
scope |
Scope of the variable. Default is page scope |
String |
False |
Declaring a variable
To declare any variables use the c:set tag to define the variable, and use the var attribute to name the object to be referenced later. Use the value attribute to set the actual value to the object. Once the variable is declared use expression syntax to access the object in that page. We can also use the <c:out> tag to display the expression.
Example of JSTL Core <c:set> Tag
Below is the implementation of the above topic:
<%@ page language="java" contentType="text/html; charset=ISO-8859-1" pageEncoding="ISO-8859-1"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%> <!DOCTYPE html> <html>
<head>
<meta charset="ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
<c:set var="userName" value="ragul21" />
<h1> Your user name is : ${userName} </h1>
</body>
</html>
|
Output:
Variable scopes
We can control the scope of a variable created with <c:set> by using the scope attribute. The possible values for the scope attribute are
- page -> accessible only within the current jsp page.
- request -> accessible by a all jsp pages in the same request.
- session -> accessible for the entire session.
- application -> accessible throughout the application.
Edxample of JSTL Core Variable Scopes
<%@ page language="java" contentType="text/html; charset=ISO-8859-1" pageEncoding="ISO-8859-1"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%> <!DOCTYPE html> <html>
<head>
<meta charset="ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
<c:set var="count" value="42" scope="session" />
<p>Count in session: ${count}</p>
</body>
</html>
|
Output:
Conclusion
The JSTL Core <c:set> tag is a versatile tool for variable creation and assignment in JSP pages. It helps improve code readability and maintainability by eliminating the need for scriptlet code. Whether you need to set values, control variable scope, or perform conditional assignments, the <c:set> tag empowers you to handle variables more efficiently in your JSP applications. By incorporating this tag into your JSP development, you can create cleaner, more robust, and more maintainable web applications.