By: Fazal Emailed: 1790 times Printed: 2614 times
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.
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