實體類與數據庫字段的映射常見錯誤（at org.hibernate.property.BasicPropertyAccessor$BasicSetter.set）

嚴重: Servlet.service() for servlet springMVC threw exception
java.lang.IllegalArgumentException
	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:597)
	at org.hibernate.property.BasicPropertyAccessor$BasicSetter.set(BasicPropertyAccessor.java:66)
	at org.hibernate.tuple.entity.AbstractEntityTuplizer.setPropertyValues(AbstractEntityTuplizer.java:583)
	at org.hibernate.tuple.entity.PojoEntityTuplizer.setPropertyValues(PojoEntityTuplizer.java:229)
	at org.hibernate.persister.entity.AbstractEntityPersister.setPropertyValues(AbstractEntityPersister.java:3822)
	at org.hibernate.engine.TwoPhaseLoad.initializeEntity(TwoPhaseLoad.java:152)
	at org.hibernate.loader.Loader.initializeEntitiesAndCollections(Loader.java:982)
	at org.hibernate.loader.Loader.doQuery(Loader.java:857)
	at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:274)
	at org.hibernate.loader.Loader.doList(Loader.java:2533)
	at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2276)
	at org.hibernate.loader.Loader.list(Loader.java:2271)
	at org.hibernate.loader.custom.CustomLoader.list(CustomLoader.java:316)
	at org.hibernate.impl.SessionImpl.listCustomQuery(SessionImpl.java:1842)
	at org.hibernate.impl.AbstractSessionImpl.list(AbstractSessionImpl.java:165)
	at org.hibernate.impl.SQLQueryImpl.list(SQLQueryImpl.java:157)

原因：數據庫字段值爲NULL,int 類型不能賦值爲NULL，只能爲0，但有些實際應用中，如學生分數，0表示0分，NULL，則表示暫無分數所以，要不設數據字段不爲NULL，要不就是用Integer.