The Tag Life Cycle with Attributes in JSP

By: Fazal Emailed: 1757 times Printed: 2444 times    

Latest comments
By: rohit kumar - how this program is work
By: Kirti - Hi..thx for the hadoop in
By: Spijker - I have altered the code a
By: ali mohammed - why we use the java in ne
By: ali mohammed - why we use the java in ne
By: mizhelle - when I exported the data
By: raul - no output as well, i'm ge
By: Rajesh - thanx very much...
By: Suindu De - Suppose we are executing

Introducing attributes into a custom tag does change the tag life cycle slightly because before the functionality of the tag can be executed (the doTag() method in the case of simple tags), the attributes must be passed to the tag handler so that they can be used by the tag. The way that the JSP specification allows this is through properties and setter methods of the tag handler class. A tag handler must have a property and a setter method for every attribute that it supports.

Note The necessity for the tag handler to have a property and setter method for every supported attribute is a requirement of previous versions of the JSP specification. But with the introduction of dynamic attributes, this is not strictly true anymore. 

These setter methods must conform to the standard JavaBeans naming convention, meaning that to support an attribute called name of type String, the tag handler must declare a setter method with the following signature:

public void setName(String s)

In this example, at request time, the value of the name attribute will be passed to the setName() method. With this in mind, you can now see how supporting attributes alters the tag life cycle. As an example, consider the following custom tag usage:

<prefix:myTag attribute1="abc" attributeN="def"/>

Here, the tag has two attributes that are being specified. By looking at the tag life cycle in Figure below, you can see what happens behind the scenes.\

The life cycle of a simple tag with parameters

As this diagram shows, the setter methods for the attributes are called before the doTag() method is executed, and in the same order that the attributes appear within the usage of the tag, from left to right. When it comes to implementing attributes in tag handler classes, attribute setter methods typically store a copy of the attribute away in an instance variable, ready for the doTag() method to use.


JSP Home | All JSP Tutorials | Latest JSP Tutorials

Sponsored Links

If this tutorial doesn't answer your question, or you have a specific question, just ask an expert here. Post your question to get a direct answer.



Bookmark and Share

Comments(0)


Be the first one to add a comment

Your name (required):


Your email(required, will not be shown to the public):


Your sites URL (optional):


Your comments:



More Tutorials by Fazal
The Tag Life Cycle with Attributes in JSP
Using Shift Operators in C
IncludeAction in Struts
typedef example program in C
Arithmetic Evaluation Using the Expression Language in JSP
Tutorial on Complicated Declarations in C
Static Variables in C
getPosition() the right strategy in getting GPS
Precedence and Order of Evaluation in C
File Copying in C
JSF Life Cycle
Getting User Input Using cin in C++
UDP Datagram sample in J2ME
GUI components and menu based J2ME Applications.
A Serialization Example in Java

More Tutorials in JSP
LifecycleException: service.getName(): "Catalina"; Protocol handler start failed: `java.net.BindException: Permission denied <null>:80
JSP Alert Example
JSP CheckBox Example
Uploading an Image to a Database using JSP
Uploading a file to a server using JSP
A JSP page that gets properties from a bean
The page Directive in JSP
The taglib, tag, include, attribute and the variable Directive in JSP
Declarations in JSP
Scriptlets and Expressions in JSP
Tag Libraries in JSP
The Request Object in JSP
The Response Object in JSP
The Out Object in JSP
The Session Object in JSP

More Latest News
Most Viewed Articles (in JSP )
JSP Example to connect to MS SQL database and retrieve records
What are the different scopes in JSP?
JSP Alert Example
Comparison operators in JSP
JSP Program for display Date
JSP CheckBox Example
Sending Email using JSP
Disabling Scriptlets in JSP using web.xml
Uploading an Image to a Database using JSP
Enable/Disable Scripting Elements in JSP
Embedding java codes in jsp sciptlets
Arithmetic Evaluation Using the Expression Language in JSP
Writing your first JSP page
JSP Example to connect to MS SQL database using Tomcat Connection Pool
Uploading a file to a server using JSP
Most Emailed Articles (in JSP)
The taglib, tag, include, attribute and the variable Directive in JSP
What is JSP?
Cookies using JSP or Java Bean
Click to Activate and Use this control
The JSP Program running first Time.
Scriptlets
Server Side Programming
Syntax For JSP Declaratives
Embedding java codes in jsp sciptlets
Tags using in jsp
JSP pages in servlet
Combining Scriptlets with HTML
JSP Directives
Form processing in JSP
Declaring variable in JSP