Hibernate报错解决问题

1.
java.lang.NoClassDefFoundError: org/hibernate/Session的异常

http://fehly.iteye.com/blog/621365

2.java.lang.NoClassDefFoundError: org/hibernate/Session
http://hi.baidu.com/052caimin/blog/item/18b31ded5d4205d3b31cb125.html
java.lang.NoClassDefFoundError: org/hibernate/Session


程序编译没错啊

写main测试是 可以插入数据库的
通过界面注册信息 然后用servlet调用插入方法就插不了了

错误原因：

hibernate3.jar只在eclipse的build_path里add external jar进去了

但是WEB-INF下要建立一个lib文件夹，把hibernate3.jar等所需要的jar包放进去才行！

3. java.lang.NoClassDefFoundError: org/apache/log4j/Level 异常
http://topic.csdn.net/u/20110104/17/bb29e7f5-6304-476e-af66-2a53c97fd89d.html* log4j-1.2.15.jar 这个包 或者更高版本的...


4.%%%% Error Creating SessionFactory %%%%
http://blog.csdn.net/jishijun204/archive/2007/12/09/1925910.aspx

org.hibernate.MappingException: duplicate property mapping: customer
at org.hibernate.mapping.PersistentClass.checkPropertyDuplication(PersistentClass.java:414)
at org.hibernate.mapping.PersistentClass.validate(PersistentClass.java:404)
at org.hibernate.mapping.RootClass.validate(RootClass.java:192)
at org.hibernate.cfg.Configuration.validate(Configuration.java:984)
at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1169)
at com.sily.hib.HibernateSessionFactory.<clinit>(HibernateSessionFactory.java:31)
at com.sily.hib.dao.BaseHibernateDAO.getSession(BaseHibernateDAO.java:15)
at com.sily.hib.dao.OrdersDAO.saveCustomerAndOrder(OrdersDAO.java:144)
at com.sily.hib.dao.OrdersDAO.main(OrdersDAO.java:173)
%%%% Error Creating SessionFactory %%%%
org.hibernate.MappingException: Could not read mappings from resource: com/sily/hib/po/Usr.hbm.xml
at org.hibernate.cfg.Configuration.addResource(Configuration.java:485)
at org.hibernate.cfg.Configuration.parseMappingElement(Configuration.java:1465)
at org.hibernate.cfg.Configuration.parseSessionFactory(Configuration.java:1433)
at org.hibernate.cfg.Configuration.doConfigure(Configuration.java:1414)
at org.hibernate.cfg.Configuration.doConfigure(Configuration.java:1390)
at org.hibernate.cfg.Configuration.configure(Configuration.java:1310)
at com.sily.hib.HibernateSessionFactory.rebuildSessionFactory(HibernateSessionFactory.java:69)
at com.sily.hib.HibernateSessionFactory.getSession(HibernateSessionFactory.java:53)
at com.sily.hib.dao.BaseHibernateDAO.getSession(BaseHibernateDAO.java:15)
at com.sily.hib.dao.OrdersDAO.saveCustomerAndOrder(OrdersDAO.java:144)
at com.sily.hib.dao.OrdersDAO.main(OrdersDAO.java:173)
Caused by: org.hibernate.DuplicateMappingException: Duplicate class/entity mapping com.sily.hib.po.Usr
at org.hibernate.cfg.Mappings.addClass(Mappings.java:118)
at org.hibernate.cfg.HbmBinder.bindRoot(HbmBinder.java:154)
at org.hibernate.cfg.Configuration.add(Configuration.java:386)
at org.hibernate.cfg.Configuration.addInputStream(Configuration.java:427)
at org.hibernate.cfg.Configuration.addResource(Configuration.java:482)
... 10 more
java.lang.NullPointerException
at com.sily.hib.dao.OrdersDAO.saveCustomerAndOrder(OrdersDAO.java:146)
at com.sily.hib.dao.OrdersDAO.main(OrdersDAO.java:173)
end.

重复的属性映射关系.报的错是customer,其实不是customer.hbm.xml的配置重复,而是与cumstomer有映射关系的另一个orders.hbm.xml配置中出现了重复,把重复去掉就行了.

我的问题出现的原因:软件自动生成了映射关系， 而自己还去配置了一个， 所以出错了.出错的时候,是在做一对多的关系,所以说,当时是做的一个customer对应多个orders,在orders.hbm.xml中出现的重复是
<many-to-one name="customer" class="Customer" not-null="true"
         cascade="all">
         <column name="customer_id"></column>
        </many-to-one>
这个语句写了俩次.去掉一个就行了.我想报的错应该就是红色的标记这个地方.

http://haiganghou.blog.sohu.com/86083386.html5. hibernate 3.0 org.hibernate.InvalidMappingException: Could not parse mapping document

http://topic.csdn.net/u/20090219/16/3c5b3b3a-0920-4705-99f8-0c4cc184a15b.html

6.org.hibernate.AssertionFailure: null id in xxx.xx.xx的问题
http://tcrct.iteye.com/blog/690595



7.无法将 mx.utils::ObjectProxy@32b2c11 转换为 mx.collections.ArrayCollection
http://blog.csdn.net/juny0302/archive/2009/07/17/4357844.aspx

TypeError: Error #1034: 强制转换类型失败:无法将 mx.utils::ObjectProxy@32b2c11 转换为 mx.collections.ArrayCollection。

初学flex，看了官方的视频，学着做了下，没想到出现以上错误。

查了n多网页最后发现是因为我的employee.xml文件只有一个employee的原因（为了省事只写了一条记录），再添加一条eployee，错误消失。

debug以下发现，如过只有1条记录的话类型是：mx.utils.ObjectProxy

而多条记录就是：mx.collections.ArrayCollection

为什么会这样目前还不知道。


8.java.lang.OutOfMemoryError: PermGen space及其解决方法
http://blog.csdn.net/fengyie007/archive/2007/09/11/1780375.aspx

重启后解决...