Implementing result paging in hibernate (getting total number of rows)

Question

How do I implement paging in Hibernate? The Query objects has methods called setMaxResults and setFirstResult which are certainly helpful. But where can I get the total numb

Answer 1

You must do a separate query to get the max results...and in the case where between time A of the first time the client issues a paging request to time B when another request is issued, if new records are added or some records now fit the criteria then you have to query the max again to reflect such. I usually do this in HQL like this

Integer count = (Integer) session.createQuery("select count(*) from ....").uniqueResult();

for Criteria queries I usually push my data into a DTO like this

ScrollableResults scrollable = criteria.scroll(ScrollMode.SCROLL_INSENSITIVE);
if(scrollable.last()){//returns true if there is a resultset
    genericDTO.setTotalCount(scrollable.getRowNumber() + 1);
    criteria.setFirstResult(command.getStart())
            .setMaxResults(command.getLimit());
    genericDTO.setLineItems(Collections.unmodifiableList(criteria.list()));
}
scrollable.close();
return genericDTO;