从Hibernate 3升级到4后，我们正在解决沿途弹出的一些问题。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似乎在向AbstractList
这似乎只发生在一个特定的对象类型中，当保存在我们的DAO中时，但最好我们可以告诉：
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);
}
}
我们的用户项目正在保存，其中包含许多子项目，如下所示：
@OneToMany(cascade = CascadeType.ALL)
@LazyCollection(LazyCollectionOption.FALSE)
private Map<String, Project> associatedProjects = new HashMap<String, Project>();
Project类有其他类似注释的子项，但所有内容都已定义CascadeType.ALL和LazyCollectionOption.FALSE。
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的来源，或我们如何负责。使用Hibernate 4时是否存在任何潜在的陷阱（此问题是自升级以来的新问题），这可能导致部分不可修改的对象？或者这会导致Hibernate以某种方式行动，导致它试图创建不可修改的对象实例？
答案 0 :(得分：1)
@OneToMany（cascade = CascadeType.ALL） @LazyCollection（LazyCollectionOption.FALSE） private Map associatedProjects = new HashMap（）;
如何添加此内容。
@OneToMany（cascade = CascadeType.ALL）
* @ JoinColumn（name =“”） *
@LazyCollection（LazyCollectionOption.FALSE） private Map associatedProjects = new HashMap（）;
答案 1 :(得分：0)
我遇到了同样的问题（Sets而不是Lists）并且Hibernate的Persistent变量似乎试图委托给一个没有实现{的抽象基类{1}}方法。我找到的解决方案是将数据成员设置为null，执行add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。好处是它实际上有效......
答案 2 :(得分：0)
使用此交易类型：
@javax.transaction.Transactional(Transactional.TxType.REQUIRES_NEW)