JSP Implicit Objects - Developing Java Servlets - page 245

F IGURE 15.1
Output from UseRequest.jsp .

The pageContext Object
The pageContext object provides access to the namespaces associated with a JSP page. It also
provides accessors to several other JSP implicit objects.

An instance of an implementation-dependent pageContext is created by a JSP implementation
class at the beginning of the generated servlet's _jspService() method. It is created through
an implementation-dependent JspFactory . An example of the pageContext object's creation
and its use in the creation of other implicit objects is shown in the following code snippet:

pageContext = _jspxFactory.getPageContext(this, request, response,
“errorpage.jsp”, true, 8192, true);

application = pageContext.getServletContext();
config = pageContext.getServletConfig();
session = pageContext.getSession();
out = pageContext.getOut();

15

You can see by examining the previous code snippet that the pageContext is used often in the
generated servlet. However it is not often used directly in a JavaServer page. The exception to
this is in the creation of custom tags, which we will examine in Chapter 19, “Custom JSP Tag
Libraries.”