Java Enterprise Best Practices

Leverage the JSTL Classes and Interfaces

The JSTL specification includes a number of classes and interfaces you can take advantage of when you develop your own custom tag libraries, including one class that can be used by a servlet or a filter to set configuration data used by the JSTL actions (such as the default locale and resource bundle for the formatting actions). It’s beyond the scope of this book to show examples of how to use all these classes and interfaces, but here’s a list of them so that you’re at least aware of their existence and can study them in detail on your own:

javax.servlet.jsp.jstl.core.Config

This class provides methods for reading, setting, and removing configuration data used by the JSTL actions.

javax.servlet.jsp.jstl.core.ConditionalTagSupport

By extending this base class and providing an implementation of its abstract condition( ) method and your custom attribute setter methods, you get a tag handler that can be used exactly like the JSTL <c:if> action either to process its body when the condition is true or save the test result as a scoped variable.

javax.servlet.jsp.jstl.core.LoopTagStatus

An object implementing this interface can be obtained from a tag handler that implements the LoopTag interface, such as the JSTL <c:forEach> action. It provides a number of methods that tell you the current loop index, whether the first or last element is being processed, etc. This allows custom actions intended for use in the body of an iteration ...