Hibernate MappingException在MySql中使用annotation@Inheritage

Question

我使用的是Hibernate Framework3.6.10、Final和MySQL。我得到了

线程“main”org.hibernate.mappingException中的异常：无法将标识列键生成用于：org.koushik.javabrains.dto.vehicle的映射

当am在vehicle类中包含@inheritation(strategy=inheritancetype.table_per_class)时。它在这个注释中工作得很好。

vehicle.java是我的基类：

@Entity
@Inheritance(strategy=InheritanceType.TABLE_PER_CLASS)

public class Vehicle 
{

    @Id
    @GeneratedValue
    private int vehicleId;
    private String vehicleName;
        public int getVehicleId() {
        return vehicleId;
    }

    public void setVehicleId(int vehicleId) {
        this.vehicleId = vehicleId;
    }

    public String getVehicleName() {
        return vehicleName;
    }

    public void setVehicleName(String vehicleName) {
        this.vehicleName = vehicleName;
    }

}

Twowheeler.java:

@Entity
public class TwoWheeler extends Vehicle {
    private String SteeringHandle;

    public String getSteeringHandle() {
        return SteeringHandle;
    }

    public void setSteeringHandle(String steeringHandle) {
        SteeringHandle = steeringHandle;
    }

}

@Entity
public class FourWheeler extends Vehicle {
    private String SteeringWheel;

    public String getSteeringWheel() {
        return SteeringWheel;
    }

    public void setSteeringWheel(String steeringHandle) {
        SteeringWheel = steeringHandle;
    }

}

public class HibernateTest {
    public static void main(String[] args)
    {

        Vehicle vehicle = new Vehicle();
        vehicle.setVehicleName("audi"+(int)(Math.random() * 100) + 1);

        TwoWheeler bike = new TwoWheeler();
        bike.setVehicleName("bike");
        bike.setSteeringHandle("Bike SteeringHandle");

        FourWheeler car = new FourWheeler();
        car.setVehicleName("car");
        car.setSteeringWheel("Car SteeringHandle");

        SessionFactory sessionFactory = new Configuration().configure().buildSessionFactory();
        Session session = sessionFactory.openSession();
        session.beginTransaction();
        session.save(vehicle);
        session.save(bike);
        session.save(car);
        session.getTransaction().commit();
        session.close();

    }
}

SLF4J:未能加载类“org.slf4j.impl.StatibloggerBinder”。slf4j:默认为无操作(NOP)记录器实现slf4j:有关更多细节，请参见http://www.slf4j.org/codes.html#staticloggerbinder。线程“main”org.hibernate.mappingException中的异常：无法使用标识列键生成，并在org.hibernate.persister.entity.unionSubclassEntityPersister.（UnionSubclassEntityPersister：90）在org.hibernate.persister.persister.persister.persister.persister.persister.persisterfactory.createClassPersister（persisterfactory.java:90)在main(HibernateTest.java:26)

Answer 1

如果使用TABLE_PER_CLASS，则必须使用以下ID生成策略:@generatedvalue(strategy=generationtype.table)