You can use JSP action element, <jsp:getProperty>, to retrieve the value of a property/instance variable which is already defined in a class.
In order to retrieve the value of a property defined in a class,
we will first have to access an object(bean) of a class by using its id, which is already created by using the <jsp:useBean> action element.
Syntax of <jsp:getProperty>
This is a syntax of <jsp:getProperty> action element with its attributes.
<jsp:getProperty name = "nameOfExistingJavaBean" property = "propertyName" />
Let's discuss the attributes of <jsp:getProperty> action element:
name
The name attribute points to the name of an existing Java Bean which is already created by using the <jsp:useBean> action element.
property
The property attribute points to an existing property/instance variable defined in a class. This attribute is given the
same value as the name of the existing property/instance variables defined in a class.
Creating a simple class in Java
Now we are going to create a Java class, A.java which has a property/instance variables named message, defined with a value, as shown below.
A.java
package decodeJava;
public class A
{
//Constructor
public A()
{
System.out.println("A");
}
//Creating a bean property named "message"
private String message = "Hello from A class";
//Getting the value of bean property named "message"
public String getMessage()
{
return message;
}
}
Make sure that you store the compiled form(.class) of this class in "WEB-INF/Classes" folder of your project or within your
project directory in Tomcat's webapps
folder, or within the Root folder of Tomcat installation.
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Using <jsp:getProperty> action
We are going to create an object(bean) of the class A.java by using the <jsp:useBean> action element and then we will refer to the same object(bean)
by using its id(already created)
and retrieve the value of its property named message defined in the same class.
GetProperty.jsp
<html>
<head>
<title>Using JSP getProperty action</title>
</head>
<body>
<jsp:useBean id="MyBean" class = "decodeJava.A" />
<b>Getting the value of property named "message" of class A </b>
<br/>
<br/>
<b>Property name :</b> message
<br/>
<b>Property value:</b> <jsp:getProperty name ="MyBean" property="message" />
<br/>
<br/>
</body>
</html>
Executing the GetProperty.jsp gives us value of the property named message, defined in the class A, by using the <jsp:getProperty> action element of JSP, as shown below.
