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From Rodrigo Ruiz <rr...@gridsystems.com>
Subject Re: Use of return statement in servlet.
Date Fri, 31 Oct 2003 09:21:40 GMT
Anthony, putting a return in a servlet code will not create any state 
problem for the servlet itself. You could have problems if you have 
opened resources that need finalization or closing before returning, for 
example DB connections, or opened streams others than the servlet input 
and ouput ones, but that depends on the code, and it is independent from 
the servlet engine.

Of course, if you do not redirect to anywhere, or display nothing, what 
you will get in the browser is a neat clean blank page ;-)

I am not sure at all, but I think JSPs could be different, depending on 
the compiler implementation. I think Jasper generated code does not have 
problems with return statements, but I check it with every new release I 
download, just in the case ;-)

What I do is to create a simplest JSP:

<!-- JSP beginning -->
Hello World
<!-- JSP end -->

And compile it. Then, looking at the generated servlet code, I check 
that no resource-freeing operations are done after writing "Hello Worl" 
to the output stream. The moment this happens, the moment I will have a 
lot of problems :-P

Hope it helps you,
Rodrigo


Antony Paul wrote:

>Thanks for the reply
>I want the browser to point to the query page if user did not provide enough
>data or an error happens like database connection is not available. I want
>user to re enter data or wait for some time .  So I dont want to use
>"requestDispatcher.forward()"  method or redirect to an error page. I want
>to know is there any problems in using the return statement in servlets/jsp.
>
>Antony Paul
>
>----- Original Message -----
>From: "Nikola Milutinovic" <Nikola.Milutinovic@ev.co.yu>
>To: "Tomcat Users List" <tomcat-user@jakarta.apache.org>
>Sent: Friday, October 31, 2003 12:00 PM
>Subject: Re: Use of return statement in servlet.
>
>
>  
>
>>Antony Paul wrote:
>>    
>>
>>>Hi,
>>>  If any one feel it off topic mark it as off topic.
>>>  I want to exit from a servlet if no database connection is available.
>>>      
>>>
>For
>  
>
>>>this can I use a return statement in the beginning of a servlet. Will it
>>>cause any state problems. I dont like putting the code in an if block.
>>>      
>>>
>There
>  
>
>>>will be lots of if blocks.
>>>      
>>>
>>A servlet is a web application component. It is invoked when a web client
>>    
>>
>makes
>  
>
>>a request. The client expects SOMETHING as a response from the server and,
>>    
>>
>thus,
>  
>
>>from the servlet.
>>
>>So, quitting with no response is not a good practice. What you should do
>>    
>>
>is
>  
>
>>display an error page. There are several ways you can do it,
>>"requestDispatcher.forward()" or throw an exception and have custom error
>>    
>>
>pages
>  
>
>>ready.
>>
>>Nix.
>>
>>
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>>
>>    
>>
>
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>
>  
>



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