avoid hard JPA 2.0 dependency

Author: jhoeller

org.springframework.orm/src/main/java/org/springframework/orm/jpa/vendor/HibernateJpaDialect.java

@@ -39,6 +39,7 @@
 import org.springframework.transaction.TransactionDefinition;
 import org.springframework.transaction.TransactionException;
 import org.springframework.transaction.support.TransactionSynchronizationManager;
+import org.springframework.util.ClassUtils;
 import org.springframework.util.ReflectionUtils;
 
 /**
@@ -53,6 +54,10 @@
  */
 public class HibernateJpaDialect extends DefaultJpaDialect {
 
+	private static final Method getEntityManagerFactoryMethod =
+			ClassUtils.getMethodIfAvailable(EntityManager.class, "getEntityManagerFactory");
+
+
 	@Override
 	public Object beginTransaction(EntityManager entityManager, TransactionDefinition definition)
 			throws PersistenceException, SQLException, TransactionException {
@@ -83,10 +88,15 @@ public Object prepareTransaction(EntityManager entityManager, boolean readOnly,
 				previousFlushMode = flushMode;
 			}
 		}
-		EntityManagerFactory emf = entityManager.getEntityManagerFactory();
-		if (emf instanceof HibernateEntityManagerFactory) {
-			SessionFactory sf = ((HibernateEntityManagerFactory) emf).getSessionFactory();
-			TransactionSynchronizationManager.bindResource(sf, session);
+		if (getEntityManagerFactoryMethod != null) {
+			// We're on JPA 2.0, enabling our exposure of the underlying Session
+			// to the underlying SessionFactory as transaction resource reference.
+			EntityManagerFactory emf =
+					(EntityManagerFactory) ReflectionUtils.invokeMethod(getEntityManagerFactoryMethod, entityManager);
+			if (emf instanceof HibernateEntityManagerFactory) {
+				SessionFactory sf = ((HibernateEntityManagerFactory) emf).getSessionFactory();
+				TransactionSynchronizationManager.bindResource(sf, session);
+			}
 		}
 		return new SessionTransactionData(session, previousFlushMode);
 	}