作为实体的密封类

Question

我试图用kotlin密封类和hibernate来解决我的继承问题。

以下是我的课程：

@Entity
@Inheritance(strategy = InheritanceType.SINGLE_TABLE)
@DiscriminatorColumn(name = "type", discriminatorType = DiscriminatorType.STRING)
sealed class LegalGuardian(
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    var id: Int? = null
)

@Entity
@DiscriminatorValue(value = "MOTHER")
data class MotherLegalGuardian(
    @OneToOne(cascade = [CascadeType.ALL], orphanRemoval = true)
    val pesel: Pesel
) : LegalGuardian()

@Entity
@DiscriminatorValue(value = "OTHER")
data class OtherLegalGuardian(
    val firstName: String,
    val lastName: String,
    @OneToOne
    val address: Address
) : LegalGuardian()

下面是抛出的poroblem：

由: org.hibernate.MappingException:无法为org.hibernate.persister.internal.PersisterFactoryImpl.createEntityPersister(PersisterFactoryImpl.java:123) at org.hibernate.persister.internal.PersisterFactoryImpl.createEntityPersister(PersisterFactoryImpl.java:123) at org.hibernate.persister.internal.PersisterFactoryImpl.createEntityPersister(PersisterFactoryImpl.java:77) at org.hibernate.internal.SessionFactoryImpl.(SessionFactoryImpl.java:348) at org.hibernate.boot.internal.SessionFactoryBuilderImpl.build(SessionFactoryBuilderImpl.java:444) at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:获得构造函数879) . 95种常见帧被忽略，原因是:无法实例化测试对象: org.hibernate.engine.internal.UnsavedValueFactory.instantiate(UnsavedValueFactory.java:43) at org.hibernate.engine.internal.UnsavedValueFactory.getUnsavedIdentifierValue(UnsavedValueFactory.java:68) at org.hibernate.tuple.PropertyFactory.buildIdentifierAttribute(PropertyFactory.java:61) at org.hibernate.tuple.entity.EntityMetamodel.(EntityMetamodel.java:141) at org.hibernate.persister.entity.AbstractEntityPersister.(( org.hibernate.persister.entity.SingleTableEntityPersister.(SingleTableEntityPersister.java:124) at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native方法)在sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) at java.lang.reflect.Constructor.newInstance(Constructor.java:423) at org.hibernate.persister.internal.PersisterFactoryImpl.createEntityPersister(PersisterFactoryImpl.java:96) . 99种常见帧被省略：：sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native方法中的java.lang.reflect.InvocationTargetException: null )在sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) at java.lang.reflect.Constructor.newInstance(Constructor.java:423) at org.hibernate.engine.internal.UnsavedValueFactory.instantiate(UnsavedValueFactory.java:40) .由: java.lang.NoSuchMethodError: X.LegalGuardian.(Lkotlin/jvm/internal/DefaultConstructorMarker；引起的109个常见帧省略)V at X.MotherLegalGuardian.(LegalGuardian.kt) .省略114个通用帧

Answer 1

我不知道hibernate是怎么工作的。但我想这个问题与密封类文档的笔记有关

密封类本身是抽象的，不能直接实例化，并且可以具有抽象成员。 密封类不允许有非私有构造函数(默认情况下它们的构造函数是私有的)。

Answer 2

看起来问题不在密封类中，而是在数据类和构造函数中。当您使用带参数的主构造函数时，不存在默认(非参数)构造函数，这是hibernate所必需的。您可以在堆栈跟踪的末尾看到原因：

X.LegalGuardian.(Lkotlin/jvm/internal/DefaultConstructorMarker;)V at X.MotherLegalGuardian.(LegalGuardian.kt)

您可以启用诺阿格和jpa-支持插件来生成no构造函数。

还可以查看这篇文章，它解释了为什么数据类不是hibernate的好选择。