如何从Java主列表中检索数据

Question

I have 10-12 tables, where my master data is there and I have to load them by using findAll() facility of hibernate.

So for all these 10-12 table I would required to write the same kind of method like this

public List<XYZType> getAllXYZType() {
    return XYZRepository.findAll();
}

So this kind of code will be repeated for 10-12 times for different entities. Is there any way so that I can make it generic ?

Answer 1

public <T> List<T> getAll(final Class<T> type) {
  Session session = sessionFactory.getCurrentSession();
  Criteria crit = session.createCriteria(type);
  return crit.list();
}

in order to use it just pass the desired class to the function and it will return the list.

Answer 2

In that case you need to make it generic, I think the Abstract Factory Pattern is what you are looking for.

Your code should be like this:

 public interface GenericDAO < T, ID extends Serializable > {
    T findById(ID id);
    List < T > findAll();
 }

Take a look at DAO Factory patterns with Hibernate for further information.

Answer 3

public static <T> List<T> getLst(final Class<T> beanClass) {
    List<T> lst = new ArrayList<T>();
    Session sess = MyUtils.getSessionFactory().openSession();
    try {
        Criteria cr= sess.createCriteria(beanClass);
        lst = cr.list();
    } catch (Exception ex) {
        ex.printStackTrace();
    } finally {
        sess.close();
    }
    return lst;
}