java - 合并现有 Hibernate 模型对象时出现 UnsupportedOperationException？

Question

在从 Hibernate 3 升级到 4 之后，我们正在解决沿途出现的一些问题。让我们特别难过的是 UnsupportedOperationException，其中现有对象从数据库中提取、调整和合并。

问题是 Hibernate 似乎正在将一个对象添加到AbstractList

当保存在我们的 DAO 中时，这似乎只发生在一种特定的对象类型上，但尽我们所能：

1. 我们没有使用任何会导致创建不可变实例的 sublist() 或 asList() 方法。
2. 检查正在保存的对象（它很大并且有很多子项）我认为它的任何子项都不是AbstractList类型。

以下是堆栈点周围的代码片段：

HibernateDao.save():

@Transactional
public void save(T item) {
    try {
        getSessionFactory().getCurrentSession().merge(item);
    } catch (Exception ex) {
        LOGGER.debug("Unable to merge", ex);
        LOGGER.warn("Unable to merge item, saving instead. (Of type " + item.getClass() + ")");
        getSessionFactory().getCurrentSession().saveOrUpdate(item);
    }
}

我们正在保存的User项目有许多子项目，定义如下：

@OneToMany(cascade = CascadeType.ALL)
@LazyCollection(LazyCollectionOption.FALSE)
private Map<String, Project> associatedProjects = new HashMap<String, Project>();

该类Project还有其他类似注释的子级，但所有内容都有CascadeType.ALL, 并已LazyCollectionOption.FALSE定义。

这是（相当高的）堆栈跟踪：

请注意，我们的代码以com.company.application

06/04 18:15:45 DEBUG [Thread-19258] hibernate.HibernateDao.save- Unable to merge
java.lang.UnsupportedOperationException
        at java.util.AbstractList.add(AbstractList.java:148)
        at java.util.AbstractList.add(AbstractList.java:108)
        at org.hibernate.collection.internal.PersistentBag.add(PersistentBag.java:292)
        at org.hibernate.type.CollectionType.replaceElements(CollectionType.java:496)
        at org.hibernate.type.CollectionType.replace(CollectionType.java:563)
        at org.hibernate.type.AbstractType.replace(AbstractType.java:178)
        at org.hibernate.type.TypeHelper.replaceAssociations(TypeHelper.java:261)
        at org.hibernate.event.internal.DefaultMergeEventListener.copyValues(DefaultMergeEventListener.java:398)
        at org.hibernate.event.internal.DefaultMergeEventListener.entityIsTransient(DefaultMergeEventListener.java:221)
        at org.hibernate.event.internal.DefaultMergeEventListener.entityIsDetached(DefaultMergeEventListener.java:282)
        at org.hibernate.event.internal.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:151)
        at org.hibernate.internal.SessionImpl.fireMerge(SessionImpl.java:914)
        at org.hibernate.internal.SessionImpl.merge(SessionImpl.java:896)
        at org.hibernate.engine.spi.CascadingAction$6.cascade(CascadingAction.java:288)
        at org.hibernate.engine.internal.Cascade.cascadeToOne(Cascade.java:380)
        at org.hibernate.engine.internal.Cascade.cascadeAssociation(Cascade.java:323)
        at org.hibernate.engine.internal.Cascade.cascadeProperty(Cascade.java:208)
        at org.hibernate.engine.internal.Cascade.cascadeCollectionElements(Cascade.java:409)
        at org.hibernate.engine.internal.Cascade.cascadeCollection(Cascade.java:350)
        at org.hibernate.engine.internal.Cascade.cascadeAssociation(Cascade.java:326)
        at org.hibernate.engine.internal.Cascade.cascadeProperty(Cascade.java:208)
        at org.hibernate.engine.internal.Cascade.cascade(Cascade.java:165)
        at org.hibernate.event.internal.DefaultMergeEventListener.cascadeOnMerge(DefaultMergeEventListener.java:439)
        at org.hibernate.event.internal.DefaultMergeEventListener.entityIsDetached(DefaultMergeEventListener.java:308)
        at org.hibernate.event.internal.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:151)
        at org.hibernate.internal.SessionImpl.fireMerge(SessionImpl.java:914)
        at org.hibernate.internal.SessionImpl.merge(SessionImpl.java:896)
        at org.hibernate.engine.spi.CascadingAction$6.cascade(CascadingAction.java:288)
        at org.hibernate.engine.internal.Cascade.cascadeToOne(Cascade.java:380)
        at org.hibernate.engine.internal.Cascade.cascadeAssociation(Cascade.java:323)
        at org.hibernate.engine.internal.Cascade.cascadeProperty(Cascade.java:208)
        at org.hibernate.engine.internal.Cascade.cascadeCollectionElements(Cascade.java:409)
        at org.hibernate.engine.internal.Cascade.cascadeCollection(Cascade.java:350)
        at org.hibernate.engine.internal.Cascade.cascadeAssociation(Cascade.java:326)
        at org.hibernate.engine.internal.Cascade.cascadeProperty(Cascade.java:208)
        at org.hibernate.engine.internal.Cascade.cascade(Cascade.java:165)
        at org.hibernate.event.internal.DefaultMergeEventListener.cascadeOnMerge(DefaultMergeEventListener.java:439)
        at org.hibernate.event.internal.DefaultMergeEventListener.entityIsDetached(DefaultMergeEventListener.java:308)
        at org.hibernate.event.internal.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:151)
        at org.hibernate.internal.SessionImpl.fireMerge(SessionImpl.java:914)
        at org.hibernate.internal.SessionImpl.merge(SessionImpl.java:896)
        at org.hibernate.engine.spi.CascadingAction$6.cascade(CascadingAction.java:288)
        at org.hibernate.engine.internal.Cascade.cascadeToOne(Cascade.java:380)
        at org.hibernate.engine.internal.Cascade.cascadeAssociation(Cascade.java:323)
        at org.hibernate.engine.internal.Cascade.cascadeProperty(Cascade.java:208)
        at org.hibernate.engine.internal.Cascade.cascadeCollectionElements(Cascade.java:409)
        at org.hibernate.engine.internal.Cascade.cascadeCollection(Cascade.java:350)
        at org.hibernate.engine.internal.Cascade.cascadeAssociation(Cascade.java:326)
        at org.hibernate.engine.internal.Cascade.cascadeProperty(Cascade.java:208)
        at org.hibernate.engine.internal.Cascade.cascade(Cascade.java:165)
        at org.hibernate.event.internal.DefaultMergeEventListener.cascadeOnMerge(DefaultMergeEventListener.java:439)
        at org.hibernate.event.internal.DefaultMergeEventListener.entityIsDetached(DefaultMergeEventListener.java:308)
        at org.hibernate.event.internal.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:151)
        at org.hibernate.event.internal.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:76)
        at org.hibernate.internal.SessionImpl.fireMerge(SessionImpl.java:904)
        at org.hibernate.internal.SessionImpl.merge(SessionImpl.java:888)
        at org.hibernate.internal.SessionImpl.merge(SessionImpl.java:892)
        at com.company.hibernate.HibernateDao.save(HibernateDao.java:129)
        at sun.reflect.GeneratedMethodAccessor62.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:601)
        at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:318)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:183)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:150)
        at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:106)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
        at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:202)
        at $Proxy53.save(Unknown Source)
        at com.company.application.UserManager.save(UserManager.java:46)
        at sun.reflect.GeneratedMethodAccessor67.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:601)
        at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:318)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:183)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:150)
        at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:106)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
        at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:202)
        at $Proxy66.save(Unknown Source)
        at com.company.application.UserOperationController.saveUser(UserOperationController.java:533)

我们不确定 AbstractList 来自哪里，或者我们如何负责。使用 Hibernate 4 时是否有任何潜在的陷阱（这个问题是升级后的新问题），可能导致部分不可修改的对象？或者这会导致 Hibernate 的行为方式导致它试图创建不可修改的对象实例？

Answer 1

在这段代码中：

@OneToMany(cascade = CascadeType.ALL)
@LazyCollection(LazyCollectionOption.FALSE)
private Map<String, Project> associatedProjects = new HashMap<String, Project>();

如何添加这个。

@OneToMany(cascade = CascadeType.ALL)

*****@JoinColumn(name="")***** 

@LazyCollection(LazyCollectionOption.FALSE)
private Map<String, Project> associatedProjects = new HashMap<String, Project>();

Answer 2

我遇到了同样的问题（与Setsnot Lists），似乎 Hibernate 的 Persistent 有问题的集合变体试图委托给不实现该add方法的抽象基类。我找到的解决方案是将数据成员设置为空，merge然后将数据成员设置回我希望它包含的新列表。相当明显的缺点是即使我只想添加或删除一个记录，我也会删除所有记录。好处是它确实有效......

Answer 3

使用此交易类型：

@javax.transaction.Transactional(Transactional.TxType.REQUIRES_NEW)