Question

我有以下项目：

@Entity
@Table(name = "A")
public class A{
    @Id
    private Long id = null;

    @OneToMany(mappedBy = "a_1", cascade = CascadeType.ALL,
               fetch = FetchType.EAGER)
    private List<B> bs;
}

@Entity
@Table(name = "B")
@Inheritance(strategy = InheritanceType.SINGLE_TABLE)
@DiscriminatorColumn(name = "BTYPE",
                     discriminatorType = DiscriminatorType.STRING)
public abstract class B{
    @Id
    private Long id = null;

    @Embedded
    private C c;

    @ManyToOne(cascade=CascadeType.REFRESH)
    @JoinColumn(name="a_id")
    @XmlTransient
    private A a_1;
}

@Embeddable
public class C {
@OneToMany(mappedBy = "b_1", cascade = CascadeType.ALL,
           fetch = FetchType.EAGER))
    private Set<D> ds;
}

@Entity
@Table(name = "D")
public class D {
@ManyToOne(cascade=CascadeType.REFRESH)
    @JoinColumn(name="b_id")
    private B b_1;
}

@Entity
@DiscriminatorValue(value = "X_D")
public class X extends B {

}

@Entity
@DiscriminatorValue(value = "Y_D")
public class Y extends B {

}

所有这些类都实现了Serializable，除了X和Y

当我调用entityManager.merge（A）时我明白了：

引起：org.hibernate.InstantiationException：无法实例化抽象类或接口：B

请问有人帮我吗？

提前举手

Answer 1

我看到类似的问题，人们不得不在这里制作具体的课程（X和Y）以实现Serializable以使其发挥作用

Hibernate无法实例化抽象类或接口

1 个答案: