Hibernate one to one mapping using only foreign id

Given we have

tables Person (id, address_id) and Address (id, town)

and POJO

class Person {

 int id;
 int addressId;  

}

class Address{开发者_如何学运维

int id;

String town;

}

Is is possible to map an address to a person? (Hibernate)

*Querying a Person will only get it's id and it's address id

Is it also possible to search a person by his/her town?

UPDATE: I'd like to add: the Person class is restricted to use only int addressId; One reason would be that we want the Person class to be atomic (all data is independent) and use it for web services or the like

thanks in advance

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Replace the private int addressId; field in the Person by the field private Address address;, and add a @OneToOne annotation to the field.

@Entity
class Person {
  @Id
  int id;

  @OneToOne
  Address address;
}

@Entity
class Address{
   @Id
   int id;

   String town;
}

If Address is not an own table, then have a loot at the @Embeddable Annotation. (Example in Chapter 2.2.2.2. Access type of Hibernate Annotation Reference)

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Update:

I'd like to add: the Person class is restricted to use only int addressId;

you need a more complex HQL Query: see Hibernate Reference Documentation

SELECT p FROM Person as p
WHERE p.addressId in (
    SELECT a.id FROM Address AS a WHERE a.town = 'Dresden'
)

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First of all... int istn't al really good choice here as ids can be null (as long as they're not persited and get their value as @GeneratedValue and storing the addressId is cumbersome... What about

class Person {
    Integer id;
    Address address;
}

Then you could query "SELECT p.id, p.address.id FROM Person p" and "SELECT p FROM Person p WHERE p.address.town = :town"...