How to implement general pagination

Question

I am not looking for a Hibernate/JPA/JDBC implementation, but for a general design pattern.

Googling \"pagination\" gives me loads of information, lot of interestin

Answer 1

If I were you I would return not the result (Set) itself but something that encapsulates retrieval of the result. Some sort of ResultBuilder. Look:

public interface ResultBuilder {

    ResultBuilder withOffset(int offset);

    ResultBuilder withLimit(int limit);

    ResultBuilder orderedBy(String property);

    List result();
}

and then change DAO method signature:

ResultBuilder findPersonsByName(String name);

This way you can factor out business-irrelevant arguments from find-family methods. If you don't want to make client specify this params then don't make him.

Just to be clear:

public final class HibernateGenericResultBuilder implements ResultBuilder {

    private final Criteria criteria;

    public HibernateGenericResultBuilder(Criteria criteria) {
        this.criteria = criteria;
    }

    @Override public ResultBuilder withOffset(int offset) {
        criteria.setFirstResult(offset);
        return this;
    }

    @Override public ResultBuilder withLimit(int limit) {
        criteria.setMaxResults(limit);
        return this;
    }

    @Override public ResultBuilder orderedBy(String property) {
        criteria.addOrder(Order.asc(property));
        return this;
    }

    @Override public List result() {
        return new LinkedHashSet(criteria.list());
    }
}