Head First Servlets and JSP, 2nd Edition

EL and standard actions are limited

What happens when you bump into a brick wall? You can go back to scripting, of course—but you know that’s not the path.

Developers usually want way more standard actions or—even better—the ability to create their own actions.

That’s what custom tags are for. Instead of saying <jsp:setProperty>, you want to do something like <my:doCustomThing>. And you can.

But it’s not that easy to create the support code that goes behind the tag. For the JSP page creator, custom tags are much easier to use than scripting. For the Java programmer, however, building the custom tag handler (the Java code invoked when a JSP uses the tag) is tougher.

Fortunately, there’s a standard library of custom tags known as the JSP Standard Tag Library (JSTL 1.1). Given that your JSP shouldn’t be doing a bunch of business logic anyway, you might find that the JSTL (combined with EL) is all you’ll ever need. Still, there could be times when you need something from, say, a custom tag library developed specifically for your company.

In this chapter, you’ll learn how to use the core JSTL tags, as well as custom tags from other libraries. In the next chapter, we’ll learn how to actually build the classes that handle calls to the custom tags, so that you can develop your own.