Question

我有两种实体，它们之间具有双向ManyToMany关系。我不想在这里发布他们的结构，因为我觉得它不会有所帮助。该关系的任何变化都没有帮助，但该关系注释如下

// relation in the first entity class
@ManyToMany(fetch = FetchType.LAZY)
@JoinTable(name = "Entity1_Entity2",
                joinColumns = { @JoinColumn(name = "entity1") },
                inverseJoinColumns = { @JoinColumn(name = "entity2") })
private List<Entity2> subEntities = new ArrayList<>();

// relation in the second entity class
@ManyToMany(mappedBy = "relatedEntities", fetch = FetchType.LAZY)
private List<Entity1> owningEntities = new ArrayList<>();

因此可能存在循环依赖关系。但据我所知，EclipseLink以及大多数其他JPA实现都可以管理它。然而，虽然少数相关实体的持久存在没有问题，但是当它们太多时我得到StackOverflowError：

Exception in thread "main" java.lang.StackOverflowError
at org.eclipse.persistence.internal.descriptors.ObjectBuilder.extractPrimaryKeyFromObject(ObjectBuilder.java:3011)
at org.eclipse.persistence.internal.sessions.AbstractSession.getCacheKeyFromTargetSessionForMerge(AbstractSession.java:2702)
at org.eclipse.persistence.internal.sessions.MergeManager.getTargetVersionOfSourceObject(MergeManager.java:196)
at org.eclipse.persistence.internal.queries.ContainerPolicy.createWrappedObjectFromExistingWrappedObject(ContainerPolicy.java:728)
at org.eclipse.persistence.mappings.CollectionMapping.mergeIntoObject(CollectionMapping.java:1648)
at org.eclipse.persistence.internal.descriptors.ObjectBuilder.mergeIntoObject(ObjectBuilder.java:4132)
at org.eclipse.persistence.internal.descriptors.ObjectBuilder.mergeChangesIntoObject(ObjectBuilder.java:4065)
at org.eclipse.persistence.internal.sessions.MergeManager.mergeChangesOfWorkingCopyIntoOriginal(MergeManager.java:839)
at org.eclipse.persistence.internal.sessions.MergeManager.mergeChangesOfWorkingCopyIntoOriginal(MergeManager.java:698)
at org.eclipse.persistence.internal.sessions.MergeManager.mergeChanges(MergeManager.java:309)
at org.eclipse.persistence.mappings.CollectionMapping.mergeIntoObject(CollectionMapping.java:1638)
at org.eclipse.persistence.internal.descriptors.ObjectBuilder.mergeIntoObject(ObjectBuilder.java:4132)
at org.eclipse.persistence.internal.descriptors.ObjectBuilder.mergeChangesIntoObject(ObjectBuilder.java:4065)
at org.eclipse.persistence.internal.sessions.MergeManager.mergeChangesOfWorkingCopyIntoOriginal(MergeManager.java:839)
at org.eclipse.persistence.internal.sessions.MergeManager.mergeChangesOfWorkingCopyIntoOriginal(MergeManager.java:698)
at org.eclipse.persistence.internal.sessions.MergeManager.mergeChanges(MergeManager.java:309)
at org.eclipse.persistence.mappings.CollectionMapping.mergeIntoObject(CollectionMapping.java:1638)
at org.eclipse.persistence.internal.descriptors.ObjectBuilder.mergeIntoObject(ObjectBuilder.java:4132)
at org.eclipse.persistence.internal.descriptors.ObjectBuilder.mergeChangesIntoObject(ObjectBuilder.java:4065)
at org.eclipse.persistence.internal.sessions.MergeManager.mergeChangesOfWorkingCopyIntoOriginal(MergeManager.java:839)
at org.eclipse.persistence.internal.sessions.MergeManager.mergeChangesOfWorkingCopyIntoOriginal(MergeManager.java:698)
at org.eclipse.persistence.internal.sessions.MergeManager.mergeChanges(MergeManager.java:309)
at org.eclipse.persistence.mappings.CollectionMapping.mergeIntoObject(CollectionMapping.java:1638)
...

我已经删除了级联持久化，因为你可以在上面的注释中看到，因为我可以想象这会导致递归的深度。但我又得到了这个错误。当我增加允许的堆栈时，它再次起作用，但在我看来，问题并没有解决。但它告诉我递归不是无止境的。此外，错误只发生在双向关系中，因为当我使其单向时不会抛出所以问题是：当持久存在更多实体时，为什么递归深度会增加？如何在不使关系单向的情况下避免这种情况？

具有双向关系的实体持久化时的StackOverflowError

0 个答案: