Is this Dao?

[miguel lisboa]

i'm using hibernate and i've the following classes:
domain object:

 package logica;
 
import java.util.HashSet;
import java.util.Set;
 
public class Entidade {
 
private Long id;
private String nome;
private boolean pessoaSingular;
private Set contratos = new HashSet();
private Set actosMedicos = new HashSet();
 
public Entidade() {
}
 
public Entidade(boolean pessoaSingular) {
setPessoaSingular(pessoaSingular);
}
// set/get
 
} 

in order to have persistence code apart, i made:

package persistencia;
 
import java.util.List;
 
public interface InterfaceDao {
void criaOuActualiza(Object o);
Object obtemPorId(Long id);
void elimina(Long id);
List todos();
}  

and finally:

 
package persistencia;
 
import java.util.List;
 
import logica.Entidade;
import net.sf.hibernate.*;
import utilitarios.HibernateUtil;
 

public class EntidadeDao implements InterfaceDao {
Session s = HibernateUtil.getSession();
public void criaOuActualiza(Object o) {
 
Transaction t = null;
try {
t = s.beginTransaction();
} catch (HibernateException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
 
Entidade ent = (Entidade) o;
 
try {
s.saveOrUpdate(ent);
} catch (HibernateException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
try {
t.commit();
} catch (HibernateException e2) {
// TODO Auto-generated catch block
e2.printStackTrace();
}
}
 
public Object obtemPorId(Long id) {
 
Session s = HibernateUtil.getSession();
Transaction t = null;
try {
t = s.beginTransaction();
} catch (HibernateException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
Entidade ent = null;
try {
ent = (Entidade) s.load(Entidade.class, id);
} catch (HibernateException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
try {
t.commit();
} catch (HibernateException e2) {
// TODO Auto-generated catch block
e2.printStackTrace();
}
return ent;
}
 
public void elimina(Long id) {
 
Session s = HibernateUtil.getSession();
Transaction t = null;
try {
t = s.beginTransaction();
} catch (HibernateException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
Entidade ent = null;
try {
ent = (Entidade) s.load(Entidade.class, id);
} catch (HibernateException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
try {
s.delete(ent);
} catch (HibernateException e2) {
// TODO Auto-generated catch block
e2.printStackTrace();
}
 
try {
t.commit();
} catch (HibernateException e3) {
// TODO Auto-generated catch block
e3.printStackTrace();
}
}
 
public List todos() {
List lista = null;
try {
// TODO Auto-generated method stub
lista = s.find("from Convencao");
} catch (HibernateException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return lista;
}
} 

i know i do have to implement proper catching;
now, 2 Qs:
1) is this Dao?
2) is it good to use try catch instead of adding a throws hibernateException?

thanks in advance

[Craig Jackson]

1. It looks like DAO to me.

2. I would wrap a custom exception around the HibernateException. This would further enforce the client/service to code to the interface, thus further hiding the fact that you you are using Hibernate as ORM. So if you change to a different ORM, the client code will not change.

For example:

 
public interface InterfaceDao {
    void criaOuActualiza(Object o) throws EntidadeException;
    Object obtemPorId(Long id) throws EntidadeException;
    void elimina(Long id) throws EntidadeException;
    List todos() throws EntidateException;
}   
 

public class EntidateException extends Exception {
    public EntidateException(){
    }
    ...
    ...
}
 
...
 
public void criaOuActualiza(Object o) throws EntidadeException { Transaction t = null;
         try {
              t = s.beginTransaction();
         } catch (HibernateException e) {
              // TODO Auto-generated catch block      throw new EntidadeException(e);
         } 

[Craig Jackson]

My mistake forgot the last part ...

 
public void criaOuActualiza(Object o) throws EntidadeException { 
    Transaction t = null;
    try {
        t = s.beginTransaction();
    } catch (HibernateException e) {
        throw new EntidadeException(e);
}  

[miguel lisboa]

i got the idea
thanks a lot!