The state Pattern with JPA

Leo Barrientos C <[email protected]> Wed, 11 Jul 2007 00:16:17 +0200
Newsgroups gmane.comp.java.sun.ejb.general
Message-ID <1184105777.7748.20.camel@leobarrientosc-laptop>
Hello, does anybody know how to implement the State Pattern with JPA
ussing only em.find and @tags?

I need to get a Object with a concrete state object only doing em.find ,

The entity table has a id name and id_state fields; so if the id_state
is 0 i need the ConcreteStateA loaded in actualState and if 1
ConcreteStateB in actualState.

I've reading a lot, but no answers found..... helpme.

My entity is:

public class Cuenta implements Serializable {

    private static EntityManagerFactory emf =
Persistence.createEntityManagerFactory("BancoUnidadDePersistencia");

    @Id
    @Column(name = "id", nullable = false)
    private Integer id;

    @Column(name = "id_cliente", nullable = false)
    private int idCliente;

    @Column(name = "fecha_apertura", nullable = false)
    @Temporal(TemporalType.TIMESTAMP)
    private Date fechaApertura;

    @Column(name = "id_estado", nullable = false)
    private int idEstado;

    @Transient
    private AccountState actualState;

    @Transient
    private float saldo;



    /** Creates a new instance of Cuenta */
    public Cuenta() {
    }

    ..........................................

    public void execute(){
        this.actualState.execute();
    }
  }

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