Caused by: java.lang.IllegalStateException: Error occurred while storing entity [Entity {id='500228'

Caused by: java.lang.IllegalStateException: Error occurred while storing entity [Entity {id='500228'}]. An entity copy [com.qihangedu.comp.entity.AssessLevelEntity#500228] was already assigned to a different entity [Entity {id='500228'}].

at org.hibernate.event.internal.EventCache.put(EventCache.java:192)

at org.hibernate.event.internal.DefaultMergeEventListener.entityIsDetached(DefaultMergeEventListener.java:285)

at org.hibernate.event.internal.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:151)

at org.hibernate.internal.SessionImpl.fireMerge(SessionImpl.java:843)

at org.hibernate.internal.SessionImpl.merge(SessionImpl.java:825)

at org.hibernate.engine.spi.CascadingAction$6.cascade(CascadingAction.java:288)

at org.hibernate.engine.internal.Cascade.cascadeToOne(Cascade.java:396)

at org.hibernate.engine.internal.Cascade.cascadeAssociation(Cascade.java:339)

at org.hibernate.engine.internal.Cascade.cascadeProperty(Cascade.java:207)

at org.hibernate.engine.internal.Cascade.cascadeCollectionElements(Cascade.java:426)

at org.hibernate.engine.internal.Cascade.cascadeCollection(Cascade.java:366)

at org.hibernate.engine.internal.Cascade.cascadeAssociation(Cascade.java:342)

at org.hibernate.engine.internal.Cascade.cascadeProperty(Cascade.java:207)

at org.hibernate.engine.internal.Cascade.cascade(Cascade.java:164)

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:833)

at org.hibernate.internal.SessionImpl.merge(SessionImpl.java:817)

at org.hibernate.internal.SessionImpl.merge(SessionImpl.java:821)

at org.hibernate.ejb.AbstractEntityManagerImpl.merge(AbstractEntityManagerImpl.java:889)

at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)

at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)

at java.lang.reflect.Method.invoke(Method.java:606)

at org.springframework.orm.jpa.SharedEntityManagerCreator$SharedEntityManagerInvocationHandler.invoke(SharedEntityManagerCreator.java:291)

at com.sun.proxy.$Proxy51.merge(Unknown Source)

at org.springframework.data.jpa.repository.support.SimpleJpaRepository.save(SimpleJpaRepository.java:397)

at sun.reflect.GeneratedMethodAccessor216.invoke(Unknown Source)

at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)

at java.lang.reflect.Method.invoke(Method.java:606)

at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.executeMethodOn(RepositoryFactorySupport.java:442)

at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.doInvoke(RepositoryFactorySupport.java:427)

at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.invoke(RepositoryFactorySupport.java:381)

at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)

at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:99)

at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:267)

at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:96)

at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)

at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:136)

... 56 more

解决方案：

        在实体类中将List改为Set