Java Enterprise in a Nutshell, Third Edition

JSP Standard Tag Library

Many developers criticized the original JSP specification because it lacked some important basic capabilities. As we saw earlier in the chapter, you can implement complex logic within JSPs by embedding scriptlets. This approach works (at least, it’s functional and produces web pages that look about right), but it makes JSPs look a lot less like HTML and a lot more like Java code. As a result, the range of people who can work on them is sharply limited. To make things even worse, because developers were virtually forced into embedding large amounts of Java code into each page (at least if the page were in any way complex), business logic had a tendency to creep down into the presentation layer.

The JSP EL removes some of the need for scriptlets (you can now display a variable without embedding Java code directly) but doesn’t help implement page logic. That’s where the JSP Standard Tag Library (JSTL ) comes in. JSTL is not directly part of the JSP standard, but it’s an associated standard, and JSTL Version 1.1 (which is compatible with JSP 2.0) is also included in J2EE 1.4. In this section, we’ll discuss the most commonly used JSTL tags for variable handling, flow control, and internationalization.

The JSTL tags are easy to incorporate into your web applications. J2EE 1.4- compatible containers include all the necessary jar files. Standalone servlet/JSP containers, such as Tomcat, don’t, so you’ll need to obtain both the jstl.jar file and an implementation of ...