列出数据库中按给定字段休眠顺序的实体

Question

I'm starting to learn Hibernate and I'm trying to list entities from postgresql database. I have a table "dbuser". Then I have a mapping of Dbuser class.

@Entity
@Table(name = "dbuser", schema = "public", catalog = "postgres")
public class DbuserEntity {
private int id;
private String username;
private String createdBy;
private Date createdDate;
private String firstName;
private String lastName;

@OrderBy("firstName")
public List<DbuserEntity> dbusers = new ArrayList<DbuserEntity>();

//constructors

@Id
@SequenceGenerator(name="pk_sequence",sequenceName="entity_id_seq", allocationSize=1)
@GeneratedValue(strategy=GenerationType.AUTO,generator="pk_sequence")
@Column(name = "id")
public int getId() {
    return id;
}

public void setId(int id) {
    this.id = id;
}

@Basic
@Column(name = "username")
public String getUsername() {
    return username;
}

public void setUsername(String username) {
    this.username = username;
}

// other getters and setters, equals etc.

Then I have method in class Service to read all entities from table:

    public List readAll() {
    HibernateUtils hibernateUtils = new HibernateUtils();
    Session session = null;
    List users = new ArrayList<DbuserEntity>();
    try {
        session = hibernateUtils.getSessionFactory().openSession();
        session.beginTransaction();
        users = session.createQuery("FROM DbuserEntity ").list();

        session.beginTransaction().commit();
    } catch (HibernateException e) {
        session.beginTransaction().rollback();
        e.printStackTrace();
    } finally {
        if (session != null) {
            if (session.isOpen()) {
                session.close();
            }
        }
    }
    return users;
}

In main() method I list all entities from table. I want it to be sorted by firstName.

      public static void main(String[] args) {   
      Service service = new Service();
      DbuserEntity db = new DbuserEntity();
      List users = new ArrayList<DbuserEntity>();
      users = service.readAll();
      db.dbusers = users;
      for (DbuserEntity dbuser : db.dbusers) {
        System.out.println(dbuser.toString());
    }

 }
 }

And this prints me all dbusers from table.

  DbuserEntity{id=19, username='user2', createdby='admin', createddate=2014-11-19, firstname='john', lastname='johnson'}

  DbuserEntity{id=20, username='user3', createdby='admin', createddate=2014-11-19, firstname='ivan', lastname='ivanov'}

  DbuserEntity{id=26, username='newUSer', createdby='system', createddate=2014-11-21, firstname='AAA', lastname='BBB'}

but they are not sorted. I dont understand what am I doing wrong. What should I change in my code to print entities sorted?

Answer 1

createQuery("FROM DbuserEntity order by firstName").list();

生活可以轻松；-)

Answer 2

Try this

public List readAll() {
    HibernateUtils hibernateUtils = new HibernateUtils();
    Session session = null;
    List users = new ArrayList<DbuserEntity>();
    try {
        session = hibernateUtils.getSessionFactory().openSession();
        session.beginTransaction();
        users = session.createQuery("FROM DbuserEntity D ORDER BY D.FirstName ASC").list(); // Here I make changes

        session.beginTransaction().commit();
    } catch (HibernateException e) {
        session.beginTransaction().rollback();
        e.printStackTrace();
    } finally {
        if (session != null) {
            if (session.isOpen()) {
                session.close();
            }
        }
    }
    return users;
}

Answer 3

You can use Criteria to build your queries.

Criteria criteria = session.createCriteria(DbuserEntity.class).setResultTransformer(Criteria.DISTINCT_ROOT_ENTITY);
criteria.addOrder(Order.asc("firstName"));
List list = criteria.list();

session.beginTransaction().commit();