Session session = objectContext.openSession();
Transaction tx = null;
try {
    tx = session.beginTransaction();
    // delete any studies that already exist that have the same name
    String name = studyElement.attributeValue("name");
    List studies = session.find("select from Study as study where study.name = ?", name, Hibernate.STRING);
    if (!studies.isEmpty()) {
        for (int i = 0; i < studies.size(); i++) {
            Study study = (Study)studies.get(i);
            log.debug("deleting study named: " + study.getName());
            session.delete(study);
        }
    }
    tx.commit();
    tx = null;
    tx = session.beginTransaction();
    Study study = new Study();
    // set study properties
    session.save(study);
    // create study children and save them, associate with study, etc., etc.
    tx.commit();
} catch (Exception e) {
    log.error("Error importing data", e);
    if (tx != null) {
        log.debug("Rolling back...");
        tx.rollback();
        log.debug("done rolling back: "+tx.wasRolledBack());
    }
    throw e;
} finally {
    session.close();
}

   <target name="initdb"
      description="builds the tables we need in the database">
      <java classname="net.sf.hibernate.tool.hbm2ddl.SchemaExport" fork="true">
         <arg value="--config=/hibernate.cfg.xml"/>
         <arg value="--delimiter=type=InnoDB"/>
         <classpath>
            <pathelement location="${dist.dir}/${jar.file}" />
            <path refid="classpath" />
         </classpath>
      </java>
   </target>

public void testCreateExistsLoginEditAndDeleteSubscriber() {
   logger.debug("testing rollback");
   Transaction tx = null;
   try {
      tx = SESSION.beginTransaction();
      // create
      Subscriber me = new Subscriber("Testing","Test",TEST_USERNAME,TEST_PASSWORD);
      me.setEmail("[email protected]");
      Long id = SubscriberPeer.save(SESSION,me);

      // force an error to get it to abort.
      assertNull("id was null.",id);

// snip out irrelevent code

      tx.commit();
   } catch (Error er) {
      // abort the transaction.
      logger.error("caught an error: "+er.getMessage());
      try {
         if (tx != null) {
            logger.debug("rolling back transaction after an error");
            tx.rollback();
         }
      } catch (HibernateException he) {
         logger.error("HibernateException while aborting transaction. "+
                                             he.getMessage());
      }
      throw er;
   } catch (Exception ex) {
      // abort the transaction.
      logger.error("caught an exception: "+ex.getMessage());
      try {
         if (tx != null) {
            logger.debug("rolling back transaction after an exception");
            tx.rollback();
         }
      } catch (HibernateException he) {
         logger.error("HibernateException while aborting transaction. "+
                                             he.getMessage());
      }
   }

}

public void tearDown() throws Exception {
   super.tearDown();
   SESSION.close();
}