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From Bob Marcum <bmar...@BCScomputers.com>
Subject Seeking the right solution to java.lang.ClassNotFoundException: com.mysql.jdbc.Driver
Date Mon, 20 Jul 2009 19:32:07 GMT
I have been experiencing "java.lang.ClassNotFoundException: com.mysql.jdbc.Driver" when attempting
to run my webapp under tomcat 6.0.18.  I have run my application successfully before under
prior versions of Tomcat. I have found and implemented a solution that works, but I believe
it is a "wrong" solution and I want to provoke some discussion about a "right" solution. 
Let me explain:

My environment:
	Tomcat 6.0.18
	jse 1.6.0_05
	using hibernate 3.0
	using mySQL standard-4.1.14
My development environment is driven by Ant 1.6.5
and ... irrelevant to the issue but ... my front end code is Google Web Toolkit (GWT) based.

Now ...
I kept getting mysql driver class not found at runtime.  I have the driver mysql-connector-java-3.1.10-bin.jar
file in myapp/WEB-INF/lib.  I would have thought that would have solved the problem in a nice,
tidy fashion, but it did not.  After further investigation of the Tomcat 6 class loading mechanism
I found this bit of information: "...plus classes and resources in JAR files under the /WEB-INF/lib
directory of your web application archive, are made visible to the containing web application,
but to no others."  I believe I am being caught on that "but to no others" phrase.  That would
mean code directly in my app could see all the jar files in WEB-INF/lib but hibernate code,
for instance, could not ?? !! even though conceptually the hibernate code is configured to
be an integral part of my app ??

A solution I found to work is to copy the mysql-connector-java-3.1.10-bin.jar file into my
jseHOME/jre/lib/ext directory.  Now my app can see the driver at runtime just fine.  But ...
that seems a "wrong" solution to me.  A "right" solution would bundle access to that jar file
into the  configuration of my webapp, which is what I expect and get when I put library jar
files in WEB-INF/lib.

Is there a "more right" solution that allows me to keep the library jar files for the mysql
driver more closely bundled with my app, rather than force it to be seen be all users of java
se 1.6.0_05?? ... and still meet the requirements of Tomcat's class loading mechanisms?

Thanks.

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