Raj:
Just want to mention that anything that my understanding is that code in the
init() method is executed *exactly once* when the servlet class is first loaded.
This may answer your question.
Geeta
Raj Kumar Jha wrote:
> Hi,
> I have a similar question. I have a servlet that does some database
> updates. Now I am connecting to the database and preparing the statement in
> the init method of the servlet. Now I want to know that if different threads
> of this servlet execute the service method concurrently, will that create
> inconsistent results as my Prepared Statement is declared outside the
> service method.
> Thanks in Advance,
> Raj
>
> ----- Original Message -----
> From: Bo Xu
> To: [EMAIL PROTECTED]
> Sent: Thursday, October 12, 2000 7:50 PM
> Subject: Re: A question about the fundamentals!
>
> Hi,
>
> > ... I believe that you should not declare objects that will have dynamic
> data
> > outside of the method that is using them. I removed the declaration from
> >the class level and declared the Result Bean in the doGet method where
> >it is used. Now I can have as many web browser executing at the same
> >time and all displaying the correct information. ...
>
> I got the same "result :-) " from my testing, and I just try to add a note,
> I am
>
> sorry some of the following have already been explained in several emails,
> I just want to explain it more clear :-)
>
> 0 for the servlet engine which only make ONE instance for
> "our custom servlet class" -- normally(I guess) :
> a -- for "static class variable"
> [a] all the "static class variable" will be "shared" to all
> new threads -- and to all "client reauestings" , this is
> because now we have only one "custom servlet
> class" .
> [b] So we can not use it as "dynamic data" which is
> different to every "client requesting".
> [c] But we can use it to lock our code between those threads.
>
> b -- for "not_static class variable"
> [a] all the "not_static class variable" will be "shared" to all
> new threads -- and to all "client reauestings" , this is
> because now we have only one instance.
> [b] So we can not use it as "dynamic data" which is
> different to every "client requesting".
> [c] But we also can use it to lock our code between those
> threads.
>
> c -- for "method variable"
> [a] all the "method variable" will NOT be "shared" to all
> new threads -- and NOT to all "client reauestings" I
> guess
> this is
> because every new thread will use its own "copy"
> for these "method variable"
> [b] So we can use it as "dynamic data" which is
> different to every "client requesting".
> [c] But we can NOT use it to lock our code between those
> threads.
>
> 1 for the servlet engine which will make "instance pool" for
> "our custom servlet class" , I don't know :-) But it seems
> that now these instances are "independent:-) ", if So, I
> guess 0-a and 0-c are still right, but 0-b is not right.
>
> Bo
> OCT.12, 2000
>
> Marc Krisjanous wrote:
>
> > Hi all,
> >
> > once again thank you for your comments about exception handling. I have
> now
> > revised by strategy.
> >
> > One thing I would like to share with you is:
> >
> > I had a simple servlet that accepts a parameter from a requesting page, it
> > then adds the parameter to a Result Bean, the bean is then added to the
> > session object. A JSP page was then called. The JSP page then displayed
> > the results by accessing the Result bean and extracting the parameter
> value.
> > It worked. Now I had 3 web browsers loaded on my machine and added
> > different values to each text box (one per web page). I then executed the
> 3
> > Web Pages at the same time. Well! the results were different! Sometimes
> all
> > pages showed the same result and sometimes 2 would etc... It took me a
> > while to understand what had happened; I add declared by Result bean at
> the
> > class level - outside of a method. I believe that you should not declare
> > objects that will have dynamic data outside of the method that is using
> > them. I removed the declaration from the class level and declared the
> > Result Bean in the doGet method where it is used. Now I can have as many
> > web browser executing at the same time and all displaying the correct
> > information.
> >
> > Am I correct in my assumptions - it seems very fundamental.
> >
> > Best Regards
> >
> > Marc
> >
> >
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