JavaServer Pages, 3rd Edition

JSP Elements

There are three types of JSP elements you can use: directive, action, and scripting. A new construct added in JSP 2.0 is an Expression Language (EL) expression; let’s call this a forth element type, even though it’s a bit different than the other three.

Directive elements

The directive elements, shown in Table 3-1, specify information about the page itself that remains the same between requests—for example, if session tracking is required or not, buffering requirements, and the name of a page that should be used to report errors, if any.

Table 3-1. Directive elements

Element	Description
<%@ page ... %>	Defines page-dependent attributes, such as session tracking, error page, and buffering requirements
<%@ include ... %>	Includes a file during the translation phase
<%@ taglib ... %>	Declares a tag library, containing custom actions, that is used in the page

Standard action elements

Action elements typically perform some action based on information that is required at the exact time the JSP page is requested by a browser. An action can, for instance, access parameters sent with the request to do a database lookup. It can also dynamically generate HTML, such as a table filled with information retrieved from an external system.

The JSP specification defines a few standard action elements, most of them listed in Table 3-2.^[1]

Table 3-2. Standard action elements

Action element	Description
<jsp:useBean>	Makes a JavaBeans component available in a page
<jsp:getProperty> ...