分析hibernate中table per class hierarchy映射方式的一个异常

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Hibernate Java junit Eclipse SUN

hibernate中，对于table per class hierarchy(每个类一张表)的映射继承方式，可能会遇到的问题
若是这样3个标T_A、T_B、T_C，T_A是主表，T_B与T_C是2个子表；
这3个表分别对应3个类A、B、C

若T_A表存在一条主键是001的记录，且同时在T_B、T_C两张表中都存在一条主键是001的记录(若通过标准的UI操作不会出现这样的记录，一般都是在开发过程中，手动修改数据，而且数据库也认为这样数据是合理的)，这是，我们若想主键为001的B对象的话，hibernate就会跑出下面异常

记住：以后遇到遮掩的异常，就你的两个子表中存在相同主键的记录，只要删除一条就可以了
org.hibernate.WrongClassException: Object with id: 001 was not of the specified subclass: B (loaded object was of wrong class)
at org.hibernate.loader.Loader.instanceAlreadyLoaded(Loader.java:1235)
at org.hibernate.loader.Loader.getRow(Loader.java:1186)
at org.hibernate.loader.Loader.getRowFromResultSet(Loader.java:569)
at org.hibernate.loader.Loader.doQuery(Loader.java:689)
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:224)
at org.hibernate.loader.Loader.loadCollection(Loader.java:1919)
at org.hibernate.loader.collection.CollectionLoader.initialize(CollectionLoader.java:36)
at org.hibernate.persister.collection.AbstractCollectionPersister.initialize(AbstractCollectionPersister.java:520)
at org.hibernate.event.def.DefaultInitializeCollectionEventListener.onInitializeCollection(DefaultInitializeCollectionEventListener.java:60)
at org.hibernate.impl.SessionImpl.initializeCollection(SessionImpl.java:1676)
at org.hibernate.collection.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:344)
at org.hibernate.collection.AbstractPersistentCollection.read(AbstractPersistentCollection.java:86)
at org.hibernate.collection.PersistentSet.iterator(PersistentSet.java:138)
.............
at net.sf.cglib.proxy.MethodProxy.invoke(MethodProxy.java:149)
at org.hibernate.proxy.CGLIBLazyInitializer.intercept(CGLIBLazyInitializer.java:161)
.............
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at junit.framework.TestCase.runTest(TestCase.java:154)
at junit.framework.TestCase.runBare(TestCase.java:127)
at junit.framework.TestResult$1.protect(TestResult.java:106)
at junit.framework.TestResult.runProtected(TestResult.java:124)
at junit.framework.TestResult.run(TestResult.java:109)
at junit.framework.TestCase.run(TestCase.java:118)
at org.eclipse.jdt.internal.junit.runner.junit3.JUnit3TestReference.run(JUnit3TestReference.java:128)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:460)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:673)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:386)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:196)