SSH整合遇到的异常

摘要: 如有不正之处，请大家指点

Exception in thread "main" org.hibernate.MappingException: Unknown entity: cn.hp.model.Project

原因：<mapping resource="cn/hp/model/Project.hbm.xml" />

Exception in thread "main" java.lang.ClassCastException: [Ljava.lang.Object; cannot be cast to cn.hp.Emp

原因：生成的是一个Object数组，要通过数组的方式去读

Exception in thread "main" org.hibernate.hql.ast.QuerySyntaxError: Invalid path: 'Dept.deptno' [select sal from cn.hp.Emp group by Dept.deptno ]

原因：Dept应改为dept,此处是Emp对象的属性

Exception in thread "main" org.hibernate.QueryException: could not resolve property: deptno of: cn.hp.entity.Emp [select dept.deptno,avg(sal) from cn.hp.entity.Emp group by dept.deptno ]

原因： 3.0版本问题

Exception in thread "main" java.lang.IllegalArgumentException: node to traverse cannot be null!

原因：关键字写错了

Exception in thread "main" org.hibernate.AnnotationException: @OneToOne or @ManyToOne on cn.hp.entity.Emp.dept references an unknown entity: cn.hp.entity.Dept

原因：未在hibernate.cfg.xml文件中配置Dept的映射

java.lang.NullPointerExceptionat org.hibernate.type.IntegerType.next(IntegerType.java:82)

at org.hibernate.engine.Versioning.increment(Versioning.java:131)

at org.hibernate.event.def.DefaultFlushEntityEventListener.getNextVersion(DefaultFlushEntityEventListener.java:387)

at org.hibernate.event.def.DefaultFlushEntityEventListener.scheduleUpdate(DefaultFlushEntityEventListener.java:279)

at org.hibernate.event.def.DefaultFlushEntityEventListener.onFlushEntity(DefaultFlushEntityEventListener.java:151)

at org.hibernate.event.def.AbstractFlushingEventListener.flushEntities(AbstractFlushingEventListener.java:219)

at org.hibernate.event.def.AbstractFlushingEventListener.flushEverythingToExecutions(AbstractFlushingEventListener.java:99)

at org.hibernate.event.def.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:49)

at org.hibernate.impl.SessionImpl.flush(SessionImpl.java:1028)

at org.hibernate.impl.SessionImpl.managedFlush(SessionImpl.java:366)

at org.hibernate.transaction.JDBCTransaction.commit(JDBCTransaction.java:137)

at cn.hp.test.SuoTest.test(SuoTest.java:38)

at cn.hp.test.SuoTest.main(SuoTest.java:48)//commit时出错

原因：数据库库中有个字段未赋初始值，oracle返回一个空值，在更新时报错。给那个字段赋个初始值可解决，或包装类 ？？？？

org.hibernate.TransientObjectException: object references an unsaved transient instance - save the transient instance before flushing: cn.hp.house.entity.Street

原因：在保存时，未设置级联保存。 导致在提交事务时两个实体不能同时保存

org.hibernate.AnnotationException: mappedBy reference an unknown target entity property: cn.hp.house.entity.House.user in cn.hp.house.entity.Users.house

原因：未在house中配置user对应的映射

java.lang.Exception: org.hibernate.TransientObjectException: object references an unsaved transient instance - save the transient instance before flushing: cn.hp.house.entity.Users

原因：未设置级联