EJB 3: Multiple (different) relations between two entities?

[Johannes Koch]

I need to write an EntityBean that holds a collection of EntityBeans of another type plus two single references to EntityBeans of that type. A simple example would be a customer who has a work address and a home address, and a collection of previously used addresses that also need to be stored.

The classes could look like this:

    
@Entity
public class Customer implements Serializable
{
private Integer id;
...
private Address homeAddress;
private Address workAddress;
private Address[] previousAddresses;
...
@CollectionOfElements
@IndexColumn(name="index1")
public Address[] getPreviousAddresses()
{
return previousAddresses();
}
 
@OneToOne
public Address getHomeAddress()
{
return homeAddress;
}
 
@OneToOne
public Address getWorkAddress()
{
return workAddress;
}
...
}
 
@Entity
public class Address implements Serializable
{
private Integer id;
...
}

However, I could not find any combination of annotations that would persist this setup in a sensible way. All the Addresses always get stored in one table, and I can't find a way to distinguish which address plays which "role" in the customer class when trying to write an SQL query to read them. I would especially like to avoid having to declare a Customer attribute in the Address class, since this would be redundant on the object level and would produce a lot of implementation overhead in my application.
Does anybody know how this can be done? I'm sure I am not the first person running into this need, but unfortunately, all the books, docs and tutorials I found don't cover it.

[endswel shui]

I think you maybe the way will be ok

you can do that like this

    
@Entity
... 
public class Customer .. {
 
    @OneToMany(mappedBy="customer")
    private Set<Address> addresses;
}
 
@Entity
... 
public class Address .. {
    public static enum DiffAddress {
        oneAddress,
        twoAddress,
        ...
        XAddress
    }
    @ManyToOne
    private Customer customer;
 
}

[ July 03, 2008: Message edited by: endswel ]