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https://issues.apache.org/jira/browse/OPENJPA-2227?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13419586#comment-13419586
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Jody Grassel commented on OPENJPA-2227:
---------------------------------------
This problem doesn't show up in the JSE (which likely applies to JUnits)
environment because the application ClassLoader would be the ClassLoader
responsible for loading both the OpenJPA and JUnit/JSE application classes. In
a JEE environment, you have a hierarchy of ClassLoaders - in the WebSphere
case, OpenJPA would be loaded by one of the OSGi ClassLoaders, application code
lives in Application ClassLoaders which are children of the OSGi ClassLoaders.
When SequenceMetaData initializes, it attempts to perform a Class.forName()
lookup for the class denoted in the sequenceName entry. However, it scopes the
lookup to the ClassLoader responsible for loading the OpenJPA classes, so it
would never be able to check child ClassLoaders for application-custom
SequenceGenerators.
Curiously, the SequenceMetaData.instantiate() method takes a ClassLoader
envLoader argument (which, tracking back a couple frames in the stack trace,
originates with a call to StoreContext.getClassloader() -- which returns the
Thread Context ClassLoader that was current when the StoreContext was created.)
A modification to instantiate() to first perform the original Class.forName()
lookup, falling back to a Class.forName() lookup using envLoader if the first
call results in a ClassNotFoundException seems to resolve the issue in my test
environment.
> OpenJPA doesn't find custom SequenceGenerators
> ----------------------------------------------
>
> Key: OPENJPA-2227
> URL: https://issues.apache.org/jira/browse/OPENJPA-2227
> Project: OpenJPA
> Issue Type: Bug
> Components: kernel
> Affects Versions: 2.0.0, 2.1.0, 2.2.0
> Environment: WebSphere Application Server V8.0 and V8.5
> Reporter: Jens Leisenberg
> Assignee: Jody Grassel
> Priority: Blocker
> Attachments: ClassNotFoundException.txt
>
>
> I'm trying to use a custom SequenceGenerator within an enterprise application
> using openJPA (providing by WebSphere).
> When defining a custom Sequence a ClassNotFoundException (for the Sequence
> class) will be thrown when trying to insert data into the database.
> ExampleConfiguration:
> {code}
> @Entity
> @SequenceGenerator(name="MySequence",
> sequenceName="org.apache.openjpa.generator.UIDGenerator()")
> public class Customer implements Serializable {
> @Id
> @GeneratedValue(strategy=GenerationType.SEQUENCE, generator="MySequence")
> private long id;
> {code}
> The example will produce the stacktrace attached.
> It seems that the wrong class loader is used to instantiate the custom
> sequence class. A very similar issue seems to be: OPENJPA-758. With JavaSE
> (JUnit) all is working fine, but after deploying into WAS the Exception will
> occur.
> I think within the method SequenceMetaData.instantiate(Classloader envLoader)
> the JavaTypes.classForName() -method with parameter mustExist=false should be
> used instead of the pure Class.forName() call. But I'm not sure about the
> Metadata-parameter needed for this method call.
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