Java Reference
In-Depth Information
Listing 2-20. Usage of Common Implicit Objects
1.getServletContext().setAttribute("book", book);
2.request.setAttribute("book", book);
3.request.getSession().setAttribute("book", book);
4.application.setAttribute("book" book);
5.request.setAttribute("book" book);
6.session.setAttribute("book" book);
7.pageContext.setAttribute("book" book);
Line 1
: This sets the
book
attribute in a
ServletContext
without using implicit
objects.
Line 2
: This sets the
book
attribute in a
request
object. The
request
object is
also an implicit object in JSP. Hence, setting the attribute in a servlet is similar to
setting the attribute in a JSP page.
Line 3
: This sets the
book
attribute in the session without using implicit objects.
Line 4
: This sets the
book
attribute in the
ServletContext
using the
application
implicit object.
Line 5
: This sets the
book
attribute in a
request
object.
request
is also an implicit
object in JSP. Hence, setting the attribute in JSP is similar to setting the attribute
in a servlet.
Line 6
: This sets the
book
attribute in the session using a session implicit object.
Line 7
: This sets the
book
attribute in
PageContext
using a
pageContext
implicit
object. There is no equivalent of
pageContext
in a servlet. A
PageContext
instance provides access to all the namespaces associated with a JSP
page, provides access to several page attributes, and provides a layer above
the implementation details. Implicit objects are added to the
pageContext
automatically.
Standard Actions
The JSP standard actions provide a way to do the following:
Manipulate JavaBeans
Dynamically include files
Perform URL forwarding
The <jsp:include> Action
The
<jsp:include>
action provides a way to include at runtime the directive for including the
contents of a separate web component in the declaring JSP page. The syntax for using the standard
include action is as follows:
<jsp:include page="relativeURL" flush="true"/>
