How to call an Oracle function from Hibernate with a return parameter?

My question is very much like Getting the return value of a PL/SQL function via Hibernate

I have a function which does some modifications internally and it returns a value.

The original idea was to do something like this:

protected Integer checkXXX(Long id, Long transId)
        throws Exception {
    final String sql = "SELECT MYSCHEMA.MYFUNC(" + id + ", "
            + transId + ") FROM DUAL";
    final BigDecimal nr = (BigDecimal) this.getHibernateTemplate()
            .getSessionFactory().getCurrentSession().createSQLQuery(sql)
            .uniqueResult();
    return nr.intValue();
}

Unfortunately this doesn't work with Oracle. What is the recommended way to do something like this?

Is there a way to extract declared variables from within my statement?