Sorry but no. If the server reloaded you wouldn't get this problem.
The problem happens because when you load the new servlet a new classloader
is used. The previous data in the session object was loaded with a different
class-loader (the original one) so you get a classcast exception.
In TC 4 you can restart the entire application. TC4 will then attempt to
serialize your session state, reload the app and de-serialize your state.
Leaving the client blissfully unaware that anything happened,
Kevin Jones
DevelopMentor
www.develop.com
> -----Original Message-----
> From: A mailing list for discussion about Sun Microsystem's Java Servlet
> API Technology. [mailto:[EMAIL PROTECTED]]On Behalf Of
> Arnaud D
> Sent: 01 February 2001 17:20
> To: [EMAIL PROTECTED]
> Subject: Re: ClassCastException
>
>
> Well actually, the answer is in your question.
>
> When you store data in the session, it is stored on the server. When you
> update the .class file, your server automatically restarts cause you have
> the autoreload on.
> So the server stops and restarts, and when it does, it destroys your
> session, thus loosing all data stored in it ! Then when you ask
> for stuff in
> the session (session.getAttribute("someStuff") ), it sends back a null
> object.
> This is all very normal, I've had the same thing happen to me.
>
> Try checking to see if the Usuario object is null when you pull it out of
> the HttpSession. If it is, instantiate it. If you need data
> gotten from user
> input to instantiate it, send the user back to the first page.
>
> Hope it helped.
>
>
>
> ----- Original Message -----
> From: "João Robertson Kramer Santana" <[EMAIL PROTECTED]>
> To: <[EMAIL PROTECTED]>
> Sent: Thursday, February 01, 2001 5:41 PM
> Subject: ClassCastException
>
>
> > We are using Tomcat 3.2.1 and it is configured with "autoreload"
> > because in an developement environment we are always making
> changes to the
> > source code and don´t want to stop/start the Web Server every time a new
> or
> > upgraded servlet is ready to be tested. This has been be the ideal
> > developemnt environment for us until we started to have problems wit a
> > ClassCastException.
> > The problem is that we are using the HttpSession to store
> > information about the logged user in a class named "Usuario". There is a
> > starting servlet that is resposible for creating the user class
> ("Usuario")
> > and storing it in the HttpSession. The other classes access the
> HttpSession
> > , retreive the user object and make a cast to the class named Ususario.
> This
> > works fine until the moment we need to upgrade a class with a
> new version.
> > This time, when the "upgraded class" retreives the user object from the
> > HttpSession and tries to make a cast an ClassCastException occurs. This
> > error does not occur with the other classes that were not upgraded.
> > Are we forgetting something important about the how the servlets
> > work ? Is this a limitation or problem in the Tomcat 3.2.1
> implemntation ?
> > Can someone bring us some ligth on what is going on.
> >
> > Thanks in advance for the help.
> >
> > bye
> > jk
> >
> >
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