如何添加具有继承SINGLE_TABLE的oneToMany映射

Question

我在JPA和HIBERNATE中使用继承，所以我有这些实体：

@Entity
@Inheritance( strategy = InheritanceType.SINGLE_TABLE )
@DiscriminatorColumn( name = "entityType", 
        discriminatorType = DiscriminatorType.STRING )
public abstract class A implements Serializable
{
    @Id
    private String id;
    @ManyToOne
    @JoinColumn(name = "Z_ID", nullable = false)
    private Z z;

    // other mapped properties...
}

@Entity
@DiscriminatorValue("BB")
public class BB extends A
{
    @Basic( optional = false)
    @Column( table = "BB" )
    private String property1;

    // other mapped properties and associations...
}

@Entity
@DiscriminatorValue("CC")
public class CC extends A
{
    @ManyToOne( optional = false)
    @JoinColumn( table = "CC" )
    private SomeEntity association1;

    // other mapped properties and associations...
}
public class Z implements Serializable
{
    @Id
    private String id;
    @OneToMany(fetch = FetchType.LAZY, mappedBy = "z", cascade= CascadeType.ALL, orphanRemoval=true)
    private Set<A> as;

    // other mapped properties...
}

我知道我可以在实体Z中添加两个属性bb和cc，但是从A继承了许多其他实体，所以我问是否只有一个属性z有解决方案。 上面的实现给了我一个例外：

org.hibernate.exception.GenericJDBCException: Could not read entity state from ResultSet

这是图像的孔例外