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From David Delbecq <de...@oma.be>
Subject Re: Non-servlet class cannot access jar file in ./WEB-INF/lib when a Servlet does
Date Thu, 06 Oct 2005 14:06:49 GMT
Hi,

all classes of a webapp which do not come from tomcat server itself
do share a common classloader which is an aggregation of the various
classes in all WEB-INF/lib/*.jar and in WEB-INF/classes/**/*.class

If you get a NoClassDefFoundException, that probably mean you asked some
class in server classloader to load some other class (probably by
reflection) which
is located in WEB-INF/lib.  That simply impossible to do because
classloaders use
a child to parent classloading delegation model, not a parent (server)
to child (webapp).

Regards
David Delbecq
Jose Maria Ramirez Martinez a écrit :

>Hi, everybody
>
>I have the next problem:
>A servlet calls a non-servlet class, and this non-servlet class imports classes from a
jar file, 
>but the classloader does not find the class from the jar file
>(so when I call the servlet from an internet browser, I get a NoClassDefFoundException)
>
>But if a servlet class imports the same classes from the jar, the class loader does find
them...
>I've tried some ways to solve this problem, like:
>   a) unpacking the classes from the jar (this works, but I had the problem that 2 different
jars contained 
>a file with the same name stored in the same directory, so one would replace the other,
and the class fails)
>   b) I thought it would be a security problem so I ran tomcat with a SecurityManager,
but it didn't solve the 
>problem..
>
>does somebody has any idea why this is happening???
>can somebody help me to solve this... thanks in advance
>
>Jose Maria
>
>
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