Head First Servlets and JSP, 2nd Edition

OK, there is a little bit of configuration in the TLD

Hah! You didn’t think the solution was only in code, did ya? Of course, there is an element of configuration required. Hey, it’s the JSP spec we’re talking about here. Fortunately, the change is painless. The element you need to include is named <dynamic-attributes>:

There are no Dumb Questions

Q:	Q: You were using a Simple tag. Does this work with Classic tags, too?
A:	A: Yup, the DynamicAttributes interface can be implemented by a Classic tag in the same fashion as with a Simple tag. Even the configuration in the TLD file is the same.
Q:	Q: Do dynamic attributes accept runtime expressions, like EL or <%= %> ?
A:	A: Absolutely. By default every dynamic attribute may use EL or JSP expression tags to specify the value of the attribute. In fact, did you notice that the data type of the value parameter of the setDynamicAttribute() method is Object, and not String? This means that the value can evaluate to any Java object.
Q:	Q: What if I need to “compute” on data in a given dynamic attribute?
A:	A: You can always inspect the name parameter and decide to perform some computation or transformation of the value of that attribute. But if you need that kind of functionality, then you should probably make that attribute explicit, and perform your computation in that attribute’s setter method.
Q:	Q: What happens if the custom tag user enters an attribute ...