今天在我们的项目中发现了Hibernate 3.6的一个bug：如果把某个字段标记为“@Lob”（MySQL中将对应至LONGTEXT），并且在插入对象时该字段的值为空（null或”“），Hibernate将抛出下面的异常，导致插入失败：

Could not synchronize database state with session
org.hibernate.exception.GenericJDBCException: could not insert: [...]
at org.hibernate.exception.SQLStateConverter.handledNonSpecificException(SQLStateConverter.java:140)
at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:128)
at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:66)
at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:2436)
at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:2856)
at org.hibernate.action.EntityInsertAction.execute(EntityInsertAction.java:79)
at org.hibernate.engine.ActionQueue.execute(ActionQueue.java:273)
at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:265)
at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:184)
at org.hibernate.event.def.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:321)
at org.hibernate.event.def.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:51)
at org.hibernate.impl.SessionImpl.flush(SessionImpl.java:1216)
at org.hibernate.ejb.AbstractEntityManagerImpl.flush(AbstractEntityManagerImpl.java:795)
at ...
(...)
Caused by: java.sql.SQLException: Start position [1] cannot exceed overall CLOB length [0]
at org.hibernate.engine.jdbc.ClobProxy.invoke(ClobProxy.java:146)
at $Proxy52.getSubString(Unknown Source)
at com.mysql.jdbc.PreparedStatement.setClob(PreparedStatement.java:3542)
at com.mysql.jdbc.jdbc2.optional.PreparedStatementWrapper.setClob(PreparedStatementWrapper.java:299)
at org.apache.commons.dbcp.DelegatingPreparedStatement.setClob(DelegatingPreparedStatement.java:187)
at org.apache.commons.dbcp.DelegatingPreparedStatement.setClob(DelegatingPreparedStatement.java:187)
at org.hibernate.type.descriptor.sql.ClobTypeDescriptor$1.doBind(ClobTypeDescriptor.java:60)
at org.hibernate.type.descriptor.sql.BasicBinder.bind(BasicBinder.java:89)
at org.hibernate.type.AbstractStandardBasicType.nullSafeSet(AbstractStandardBasicType.java:282)
at org.hibernate.type.AbstractStandardBasicType.nullSafeSet(AbstractStandardBasicType.java:277)
at org.hibernate.type.AbstractSingleColumnStandardBasicType.nullSafeSet(AbstractSingleColumnStandardBasicType.java:85)
at org.hibernate.persister.entity.AbstractEntityPersister.dehydrate(AbstractEntityPersister.java:2166)
at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:2412)
... 70 more

经google，Hibernate的JIRA上已经记录了该bug：http://opensource.atlassian.com/projects/hibernate/browse/HHH-5704，10/31刚刚创建。因此在这里建议使用Hibernate的项目暂时不使用3.6版本，而是降级至3.5.2（我们的另一个项目使用了3.5.2，没有发生上述问题）