> In your JSP page, you declare a "lifespan" for the bean you are declaring in
> the USEBEAN tag. If you use a lifespan of "session", then any bean you store
> (in a servlet) with HttpSession.putValue() is available to the JSP page as a
> bean under the same name you stored it with! The only thing you have to watch
> out for is to use storage key names that are legal Java variable names,
> because (at least in the reference implementation) the generated Java code
> uses that name as the local variable that refers to the bean object.
>
> Thus, you can do things like this:
>
> * In a servlet, store a CustomerBean in the session like this:
>
> CustomerBean myCustomerBean = ....
> session.putValue("customer", myCustomerBean);
>
> * Use ResourceDispatcher.forward() to internally redirect to
> a JSP page
>
> * Access that bean like this:
>
> <USEBEAN name="customer" TYPE="CustomerBean" LIFESPAN="session">
> </USEBEAN>
>
> Similarly, if you use LIFESPAN="page", you are requesting values that the
> servlet has stored with HttpServletRequest.setAttribute().
>
> The namespaces for servlets and JSP pages are identical, so sharing
> information back and forth is really easy.
I completely agree with that. The only problem I see with this is that
you somehow rely on the way the jsp implementation will store and
retreive the beans. I know it sounds reasonable to put a session bean in
the HttpSession and a page bean in the HttpServletRequest but I think if
it is really the case it should be specified in the specification :)
In my own implementation, I have 2 methods to do it :
Jsp.getBean(javax.servlet.http.HttpServletRequest request,
String bean_name,
String lifespan)
and
Jsp.setBean(javax.servlet.http.HttpServletRequest request,
String bean_name,
String lifespan,
Object value)
and in the servlet when you want to get or set a bean in a lifespan you
just call one of those method which encapsulate the way you really store
a session bean or a page bean. I think it is a lot easier to call one of
this method than to remember where to put your bean. And in fact I had
to do it, because depending on the web server you are running it can be
different (ex: with Java Web Server you CANNOT do a
HttpServletRequest.setAttribute() for a page bean, because it is running
with JSDJ2.0... so you have to "cheat").
So I perfectly know that what I did is NOT part of the specification but
I would really like to see something like that in the 1.0 spec.
Yan
--
http://eowyn.fr.eu.org/~yan/ | [EMAIL PROTECTED]
SocialNet: Where people connect... http://www.socialnet.com
===========================================================================
To unsubscribe, send email to [EMAIL PROTECTED] and include in the body
of the message "signoff JSP-INTEREST". For general help, send email to
[EMAIL PROTECTED] and include in the body of the message "help".
