Hello,
I would like to support different databases in my app.
Today I created an example app where I defined following simple classes:
A public interface
public interface Customer
{
public int getId();
public void setId(int id);
public String getName();
public void setName(String name);
}A value object that the client can use:
public class CustomerVO implements Customer,Serializable
{
private int id;
private String name;
public int getId()
{
return this.id;
}
public void setId(int id)
{
this.id = id;
}
...
}and an EJB3 entity bean:
@Entity
@Table(name="test_cust2")
public class CustomerMySQL implements Customer,Serializable
{
private int id;
private String name;
@Column(name="id")
@Id(generate=GeneratorType.AUTO)
public int getId()
{
return this.id;
}
public void setId(int id)
{
this.id = id;
}
}For testing purpose I created a small DAO stateless session bean
@Stateless
public class CustomerDAOBean implements CustomerDAO
{
private @PersistenceContext(unitName="test") EntityManager em;
public Customer persistCustomer(Customer cust)
{
em.persist(cust);
return cust;
}
}
One might argue that I do not need a data transfer object. But in fact I need it to switch dynamically from one database to another.
Especially when I want to work with a mysql and an oracle database.
In both entity bean classes I
must use different id generator types!
My problem is that I can compile and deploy the app, but when it comes to persisting the entity bean I get an error that tells me that Customer is not an entity bean.
What do you think? Should I forget about it, or is there another approach for that problem?
Thank you!
