Answer by Reguel Wermelinger

Reguel Wermelinger — Thu, 11 Sep 2014 15:44:18 -0400

Yes there is a better way:

You should explicitly set the correct ClassLoader to a class in the JAR where you run into problems (e.g set the class loader from WrappedBlob.class)
Add a finally statement so that in case of an exception you can still reset the original context ClassLoader or the server will be in a corrupt state

So if you consider both points the code could look as follows:

public synchronized void method() {
    Thread thread = Thread.currentThread();
    java.lang.ClassLoader originalClassLoader = thread.getContextClassLoader();
    thread.setContextClassLoader(WrappedBlob.class.getClassLoader());
    try {
        entityManager.createNativeQuery(
                "select * from TSRPTBLB where TSBID = 1 ")
                .getSingleResult();
    } finally {
        thread.setContextClassLoader(originalClassLoader);
    }
}

Answers to: Not visible Interface on persistence query

Answer by Reguel Wermelinger