我有一個簡單的一對一關系：

>為每個實體單獨的DAO.

>事務由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);

每當我運行應用程序時,都會出現以下異常：

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

我嘗試保存兩個訂單中的實體：

personDao.save(person);

vehicleDao.save(vehicle);

和

vehicleDao.save(vehicle);

personDao.save(person);

和我得到同樣的例外.

我可以通過以下方法解決此問題：

>使用級聯.

>我猜想OpenSessionInView也可以.

問題是,是否有更好的解決方案？也許我在做一些根本錯誤的事情？

以下是(瑣碎的)實體和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);

}

}