Spring Hibernate开发点滴

在做开发过程中总会遇上些无厘头的错误，收集了些开发点滴，希望后来者不会踩上同一个陷阱，

1.Q:An error occured in the bean. Error Message is: Failed to lazily initialize a collection - no session or session was closed

A:未初始化加载

2. Q:org.springframework.beans.factory.BeanDefinitionStoreException: Error registering bean with name '' defined in resource [/WEB-INF/applicationContext-PoService.xml] of ServletContext: Bean class [com.itorgan.lherp.dao.impl.PoReceiveDAOImpl] not found; nested exception is java.lang.ClassNotFoundException: com.itorgan.lherp.dao.impl.PoReceiveDAOImpl

A:重启TOMCAT

3.  Q:An error occured in the bean. Error Message is: An error occurred while evaluating custom action attribute "value" with value "${poItem.poItemNo}": Unable to find a value for "poItemNo" in object of class "com.itorgan.lherp.vo.PoReceiveItem" using operator "." (null)
A:变量${poItem.poItemNo}与VO com.itorgan.lherp.vo.PoReceiveItem 无法绑定


4.   Q:org.springframework.dao.DataIntegrityViolationException: Hibernate operation: ORA-02291: integrity constraint (LH.FK_PO_RECEIVE_CUSTOMER_NO) violated - parent key not found
; nested exception is java.sql.BatchUpdateException: ORA-02291: integrity constraint (LH.FK_PO_RECEIVE_CUSTOMER_NO) violated - parent key not found

A:有对象未绑定

5.  Q:vo配置文件解释

A:*大写的部分inverse="true"表示 ParentPO 本身不维护表之间的关系！，而由想反的一方 children来维护，
   *CASCADE=“ALL”表示 无论是update,insert ,delete 都保持几连关系
   *lazy="true"表示初始化父亲的时候不会把所有的儿子都从数据库中load进来。

6.   Q:org.springframework.jdbc.BadSqlGrammarException: Bad SQL grammar [] in task 'Hibernate operation'; nested exception is java.sql.SQLException: ORA-02289: sequence does not exist

A:VO中的sequence写错

7. Q:java.lang.ClassCastException: [Ljava.lang.String;

A:类型转换错误,数据库是否有重复记录