带有 Hibernate 后端的鉴别器，WrongClassException JPA

Question

我需要有一个抽象超类。

该抽象超类有 6 个子类。

我使用 JPA 中的 SINGLE_TABLE 继承策略映射它们。

在另一个 POJO 中，我与这 1+6 个类是一对多的关系。

@OneToMany(mappedBy = "mSearchPreference", cascade = CascadeType.ALL)
private Set<SearchCriteria> mSearchCriteria;

这里的“SearchCriteria”是抽象类。

@Entity
@Table(name = "SRCH_CRTR_T", schema = "LPEW")
@Inheritance(strategy=InheritanceType.SINGLE_TABLE)
@DiscriminatorColumn(name = "SRCH_DISCRIMINATOR_CDE", discriminatorType = DiscriminatorType.STRING)
@org.hibernate.annotations.ForceDiscriminator
public abstract class SearchCriteria extends BaseDBObject implements Comparable<SearchCriteria>

它有 6 个具体的子类，比如

@Entity
@DiscriminatorValue("DATE")
@Inheritance(strategy=InheritanceType.SINGLE_TABLE)
public class SearchCriteriaDateRange extends SearchCriteria

我可以将值插入表中，但是当我检索时出现错误：

Caused by: org.hibernate.WrongClassException: Object with id: 261 was not of the specified subclass: com.lmig.lit.lpew.model.criteria.SearchCriteria (Discriminator: DATE  )
    at org.hibernate.loader.Loader.getInstanceClass(Loader.java:1453)
    at org.hibernate.loader.Loader.instanceNotYetLoaded(Loader.java:1284)
    at org.hibernate.loader.Loader.getRow(Loader.java:1206)
    at org.hibernate.loader.Loader.getRowFromResultSet(Loader.java:580)
    at org.hibernate.loader.L
10:57:44,786 INFO  [STDOUT] oader.doQuery(Loader.java:701)
    at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:236)
    at org.hibernate.loader.Loader.loadCollection(Loader.java:1994)
    at org.hibernate.loader.collection.BatchingCollectionInitializer.initialize(BatchingCollectionInitializer.java:52)
    at org.hibernate.persister.collection.AbstractCollectionPersister.initialize(AbstractCollectionPersister.java:565)
    at org.hibernate.event.def.DefaultInitializeCollectionEventListener.onInitializeCollection(DefaultInitializeCollectionEventListener.java:63)
    at org.hibernate.impl.SessionImpl.initializeCollection(SessionImpl.java:1716)
    at org.hibernate.collection.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:344)
    at org.hibernate.collection.AbstractPersistentCollection.read(AbstractPersistentCollection.java:86)
    at org.hibernate.collection.AbstractPersistentCollection.readElementExistence(AbstractPersistentCollection.java:142)
    at org.hibernate.collection.PersistentSet.add(PersistentSet.java:187)
    at com.lmig.lit.lpew.model.homescreen.HomeScreenPreference.addSearchCriteriaByType(HomeScreenPreference.java:132)
    at com.lmig.lit.lpew.model.homescreen.HomeScreenPreference.addSearchCriteriaByType(HomeScreenPreference.java:147)
    at com.lmig.lit.lpew.service.LpewUserServiceImpl.initializeHomeScreenPreferences(LpewUserServiceImpl.java:135)
    at com.lmig.lit.lpew.service.LpewUserServiceImpl.findUserAndInitialize(LpewUserServiceImpl.java:103)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:307)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:182)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:149)
    at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:106)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171)
    at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:204)
    at $Proxy122.findUserAndInitialize(Unknown Source)
    at com.lmig.lit.lpew.jsf.beans.UserSession.getLpewUser(UserSession.java:989)
    at com.lmig.lit.lpew.jsf.beans.RequestForServiceBean.getAllRequests(RequestForServiceBean.java:263)
    at com.lmig.lit.lpew.jsf.beans.RequestForServiceBean.getAllNewRequests(RequestForServiceBean.java:382)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at javax.el.BeanELResolver.getValue(BeanELResolver.java:62)
    at javax.el.CompositeELResolver.getValue(CompositeELResolver.java:53)
    at com.sun.faces.el.FacesCompositeELResolver.getValue(FacesCompositeELResolver.java:64)
    at org.apache.el.parser.AstValue.getValue(AstValue.java:97)
    at org.apache.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:186)

有人知道解决办法吗？

Answer 1

你应该在你的根实体上使用@org.hibernate.annotations.DiscriminatorOptions(force=true)

Answer 2

您的堆栈跟踪看起来就像您正在加载一组 SearchCriteria 实体。

例如： @OneToMany(mappedBy = "mSearchPreference", cascade = CascadeType.ALL) 私有设置 mSearchCriteria;

问题是 Hibernate 在不加载实体的情况下无法知道正确的子类。 所以如果集合是通过延迟加载创建的，hibernate 首先为集合中的所有实体创建 SearchCriteria 类型的代理。如果 concreate 实例加载较晚，则无法通过正确的代理来交换未创建足够的代理。

因此，“修复”是不使用代理。 这意味着你要么必须 使用急切加载 (lazy="false") 或 懒惰=“无代理”。后一种选择 需要字节码操作 编译类以使 Hibernate 拦截对 getter 的调用 方法（见 http://www.hibernate.org/hib_docs/v3/re ... 特性）。我没有经验 用这种方法，但它看起来像一个 适合您的案例。

https://forum.hibernate.org/viewtopic.php?f=1&t=996047&start=0