Java Reference
In-Depth Information
F
IGURE
5.3
The Contents of Shopping Cart screen.
To understand how this first part works, you need to examine the
doPost()
method. This is the
method that services the
POST
request sent by your HTML document.
The first thing the
doPost()
method does is get the list of submitted movies from the request.
It then tries to get a reference to the
HttpSession
object stored in the
HttpServletRequest
.
This is done by calling the
HttpServletRequest.getSession()
method. The code snippet that
performs this is listed in the following:
// Get a handle to the HttpSession Object
// if there is no session create one
HttpSession session = request.getSession(true);
The
getSession()
method takes one parameter. This parameter is a Boolean value that, if
true
, tells the method to create an
HttpSession
if one doesn't exist.
When you have a reference to the
HttpSession
object, you can add your movie list to it. You
do this by calling the
HttpSession.setAttribute()
method, passing it the name
“Movies”
and the object to be bound to it:
movies
. The movie list is now stored in the client's session.
The last thing you do in the
doPost()
method is redisplay the list of selected movies and ask
the user to click Proceed to Checkout.