Example 1: One-to-one association that maps a foreign key column
// On Customer class:
@OneToOne(optional=false)
@JoinColumn(
name="CUSTREC_ID", unique=true, nullable=false, updatable=false)
public CustomerRecord getCustomerRecord() { return customerRecord; }
// On CustomerRecord class:
@OneToOne(optional=false, mappedBy="customerRecord")
public Customer getCustomer() { return customer; }
Example 2: One-to-one association that assumes both the source and target share the same primary key values.
// On Employee class:
@Entity
public class Employee {
@Id Integer id;
@OneToOne @MapsId
EmployeeInfo info;
...
}
// On EmployeeInfo class:
@Entity
public class EmployeeInfo {
@Id Integer id;
...
}
Example 3: One-to-one association from an embeddable class to another entity.
@Entity
public class Employee {
@Id int id;
@Embedded LocationDetails location;
...
}
@Embeddable
public class LocationDetails {
int officeNumber;
@OneToOne ParkingSpot parkingSpot;
...
}
@Entity
public class ParkingSpot {
@Id int id;
String garage;
@OneToOne(mappedBy="location.parkingSpot") Employee assignedTo;
...
}