A practice which we have found to be very easy to use is to provide factory methods for Query instances in DAO implementations in the following form.

For HQL usage :

 
protected HQLQuery from(PEntity<?>... o) {
    return new HqlQueryImpl(session).from(o);
} 

For JDO usage :

protected JDOQLQuery from(PEntity<?>... o) {
    return new JDOQLQueryImpl(persistenceManager).from(o);
}