我对hibernate还不熟悉，有一项任务是将用hibernate3编写的代码迁移到hibernate5。在调试时，我得到一个错误-java.lang.illegalstateexception:事务已经处于活动状态，并且这在方法-begintransaction（）上发生。我在网上查了很多方法，但都无法纠正错误。下面是导致此错误的函数。

@Transactional(readOnly = false, propagation = Propagation.REQUIRED)
public String callStoredProc(List<UniqueNoRidVo> uniqueNoRidVoMap) throws DBException {

    List<UniqueNoRidVo> uniqueNo = null;
    String return_value = null;
    Transaction tx = null;
    int count = 0;

    Session session = sessionFactory.getCurrentSession();

    try{
        //Deleting old records from Temp table
        LOG.info("IN callStoredProc -START");
        String query = "delete from UniqueNoRidVo";
        session.createQuery(query).executeUpdate();

        LOG.info("Old records deleted from TEMP Table");

        //Inserting New RIDs into Temp table
        if(!uniqueNoRidVoMap.isEmpty()){
            tx = session.beginTransaction(); //Error code

            for(LiqVO vo : uniqueNoRidVoMap){
                session.saveOrUpdate(vo);
                if (++count % 50 == 0) {
                    session.flush();
                    session.clear();
                }
            }
            session.flush();
            LOG.info("New RIDs inserted into TEMP table");

        }
        //Calling Stored procedure to generate Unique Nos.
        LOG.info("Calling Stored Procedure");
        tx=session.getTransaction();
        System.out.println("Calling Stored Procedure");
        //migrated to hibernate 5
        //SessionFactory sessionFactory=session.getSessionFactory();
        ConnectionProvider 
          connectionProvider=liqSessionFactory.getSessionFactoryOptions().
            getServiceRegistry().getService(ConnectionProvider.class);
        Connection connection=connectionProvider.getConnection();
        CallableStatement st  = connection.prepareCall("{ call SP_FETCH_UQNO(?) }");

    //  CallableStatement st = session.connection().prepareCall("{ call SP_FETCH_UQNO(?) }");
        st.registerOutParameter(1, OracleTypes.VARCHAR);
        int abc = st.executeUpdate();

        LOG.info("abc output"+abc);
        if(abc>0) {
            return_value = st.getString(1);
        }
        LOG.info("Stored Procedure call completed: return_value "+ return_value);
        System.out.println("Stored Procedure call completed: return_value "+ return_value); 

    }catch(HibernateException hbex){
        if (tx != null) {
            tx.rollback();
            LOG.error(hbex.toString());
            System.out.println("GD004-Error occurred in getting Unique Numbers for RID"+ 
           hbex.toString());
            throw new DBException("GD004-Error occurred in getting Unique Numbers for RID", 
       hbex.toString());
        }
    } catch (SQLException sqex) {
        LOG.error(sqex.toString());
        throw new DBException("GD005-Error occurred in getting Unique Numbers for RID", 
      sqex.toString());
    }

    return return_value;

}

任何关于如何解决这个问题的建议，谢谢！