I am new to Geronimo and JavaEE in common. I need to add <gbean>
declaration for PersistenceUnitGBean in my deployment plan, am I right?
How do I set PRIORITY_CLASSLOADER? Is it an attribute of the mentioned
above <gbean> declaration? But there isn't such field in
PersistenceUnitGBean class.
 
David, thanks you for help!
 
On Птн, 2010-05-28 at 16:03 -0700, David Jencks [via Apache Geronimo]
wrote:

>
> On May 28, 2010, at 3:22 PM, SunSeaAndPalms wrote:
>
> >
> > Technologies that are used in my application requires classloader
> with
> > 'addTransformer(ClassFileTransformer)' method and claims that
> Geronimo's
> > default org.apache.geronimo.kernel.config.MultiParentClassLoader ,
> doesn't
> > have it. So I need to setup my special class loader for my
> application
> > (war). I use Geronimo with Tomcat. I was told that specifying
> classloader is
> > a very simple process on Tomcat. Following example shows how to do
> it (The
> > file is named "context.xml"):
> >
> > <Context path="/myWebApp" docBase="/my/webApp/location">
> >    <Loader
> >
> >
> loaderClass="org.springframework.instrument.classloading.tomcat.TomcatInstrumentableClassLoader"/>
> > </Context>
> >
> > The alternative for Geronimo is using "geronimo-tomcat.xml" in
> deployment
> > plan (I read about it from
> > http://www.ibm.com/developerworks/java/library/os-ag-tomcat/ this
> doc ). The
> > problem is that there isn't a classloader property specified.
> >
> > So my question is: How can I change default classloader with a
> special one
> > for my web application deployed on Geronimo?
>
> You can't change what classloader geronimo uses for your web app.
>  However, you can register a ClassTransformer quite easily.  We do
> this for jpa.  Here's the code we use, from 2.2
>  plugins/openjpa/geronimo-persistence-jpa10/src/main/java/org/apache/geronimo/persistence/PersistenceUnitGBean.java:
>
>         public void addTransformer(ClassTransformer classTransformer)
> {
>             TransformerWrapper transformer = new
> TransformerWrapper(classTransformer, classLoader);
>             transformers.add(transformer);
>             TransformerAgent.addTransformer(transformer);
>         }
>
>
> public class TransformerWrapper implements ClassFileTransformer {
>
>     private final ClassTransformer classTransformer;
>     private final ClassLoader classLoader;
>
>     public TransformerWrapper(ClassTransformer classTransformer,
> ClassLoader classLoader) {
>         this.classTransformer = classTransformer;
>         this.classLoader = classLoader;
>     }
>
>     public byte[] transform(ClassLoader loader, String className,
> Class<?> classBeingRedefined, ProtectionDomain protectionDomain,
> byte[] classfileBuffer) throws IllegalClassFormatException {
>         if (loader != classLoader) {
>             return null;
>         }
>         try {
>             return classTransformer.transform(loader, className,
> classBeingRedefined,  protectionDomain, classfileBuffer);
>         } catch (IllegalClassFormatException e) {
>             throw e;
>         } catch (RuntimeException e) {
>             return null;
>         }
>     }
> }
>
>
> If you don't care whether all classes, not just the ones in your app,
> are fed to your ClassTransformer, you can leave out the
> TransformerWrapper.
>
> This code should go in a gbean with priority PRIORITY_CLASSLOADER to
> make sure it is installed before other components are started and
> perhaps load your classes untransformed.  See the PersistenceUnitGBean
> for more details.
>
> Hope this helps
> david jencks
>
>
> >
> >
> > --
> > View this message in context:
> http://apache-geronimo.328035.n3.nabble.com/How-to-specify-classloader-for-web-application-deployed-on-Geronimo-tp853251p853251.html
> > Sent from the Users mailing list archive at Nabble.com.
>
>
>
>
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