我有一个简单的一对一关系：

>为每个实体单独的DAO.

>事务由Spring管理.

PersonDao personDao = ctx.getBean(PersonDao.class, "personDaoImpl");

VehicleDao vehicleDao = ctx.getBean(VehicleDao.class, "vehicleDaoImpl");

Vehicle vehicle = new Vehicle("Audi");

Person person = new Person("Mike");

vehicle.setPerson(person);

person.setVehicle(vehicle);

personDao.save(person);

vehicleDao.save(vehicle);

每当我运行应用程序时,都会出现以下异常：

Exception in thread "main"

org.springframework.dao.InvalidDataAccessApiUsageException:

org.hibernate.TransientPropertyValueException: object references an unsaved

mike.Person.vehicle -> mike.Vehicle; nested exception is

java.lang.IllegalStateException: org.hibernate.TransientPropertyValueException:

object references an unsaved transient instance - save the transient instance

before flushing : mike.Person.vehicle -> mike.Vehicle

我尝试保存两个订单中的实体：

personDao.save(person);

vehicleDao.save(vehicle);

和

vehicleDao.save(vehicle);

personDao.save(person);

和我得到同样的例外.

我可以通过以下方法解决此问题：

>使用级联.

>我猜想OpenSessionInView也可以.

问题是,是否有更好的解决方案？也许我在做一些根本错误的事情？

以下是(琐碎的)实体和DAO：

@Entity

public class Person {

@Id @GeneratedValue

private int id;

private String name;

@OneToOne

private Vehicle vehicle;

/* getters, setters, constructors */

}

–

@Entity

public class Vehicle {

@Id @GeneratedValue

private int id;

private String name;

@OneToOne

private Person person;

/* getters, setters, constructors */

}

–

@Repository

public class PersonDaoImpl implements PersonDao {

@PersistenceContext

private EntityManager em;

@Transactional

public void save(Person p) {

em.persist(p);

}

}

–

@Repository

public class VehicleDaoImpl implements VehicleDao {

@PersistenceContext

private EntityManager em;

@Transactional

public void save(Vehicle v) {

em.persist(v);

}

}