Exercise 20-1. Modify the HelloNet servlet so that it behaves
like the hello.jsp page. That is, if it is
invoked without a name parameter specified, it should prompt the user
to enter her name and then displays a greeting. Although you are
writing a single servlet, it should be able to display two distinct
pages of output: a greeting page and a login page. The login page
displays an HTML form, and the servlet should be able to handle
submissions from this form.
Exercise 20-2. Modify the HelloNet servlet again, as in the last
exercise. This time, however, do not hardcode the HTML for the
greeting and login pages in the servlet itself. Instead, implement
the contents of these pages in JSP files, and use the servlet as the
controller that processes the input and decides when each page should
be displayed. Your servlet class should use a
RequestDispatcher to forward the request to the
appropriate JSP page for display. It can use the session object or
request attributes to pass data from the servlet to the JSP pages.
Exercise 20-3. Modify the Counter servlet to use a database,
rather than a local file, as its persistence mechanism. Write a
CounterAdmin servlet that is an administrative
interface for the Counter servlet; it should
display (but not update) each of the counts stored in the database.
The CounterAdmin servlet should be
password-protected and should display a JSP-based login page that
requires the user to log in before the current counts are displayed.
Use a servlet initialization parameter from the
web.xml file to specify the password for the
Exercise 20-4. This chapter combines the ListManager web application with various
stand-alone examples and then packages them all into a single WAR
file. Repackage the ListManager web application by itself, and deploy
two independent instances of it on a web server to manage
subscriptions to two different mailing lists.
Exercise 20-5. The Controller servlet examines the name under
which it was invoked and uses that name to dispatch to an action
method defined within the servlet. Modify this class so that each
action is defined as a separate object. Define an interface named
ServletAction with an action( )
method that accepts servlet request parameter and response arguments
and returns a RequestDispatcher, just as the
current methods of the Controller servlet do. Then
change those methods into implementations of this new interface.
Modify the servlet so it maintains a Map of URL
action names to ServletAction objects. Initialize
the map in the servlet's init( )
Exercise 20-6. Extend the ListManager web application by adding a password-protected
administrative interface that displays all subscribers and their
preferences. The administrative password should be stored as an
initialization parameter, of course.