我开始使用Hibernate并且我遇到了这个例外，我不知道从哪里开始看。
我知道例外的开头说＆＃34;错误阅读＆＃39; frotas＆＃39;在类型br.com.wplex.cccw.mbean.FrotaMBean＆＃34;上，但那是因为错误发生在方法getFrotas（）内部，或多或少这个查询：
String hql = "from FrotaBO f order by f.aPartirDe".
getHibernateSession().createQuery(hql).list();
DadosDeCobrancaBO和ClienteBO都扩展了AbstractBO
例外：
javax.el.ELException: /cadastros/Frota/frotaLista.xhtml @24,34 value="#{frotaBean.frotas}": Error reading 'frotas' on type br.com.wplex.cccw.mbean.FrotaMBean
at com.sun.faces.facelets.el.TagValueExpression.getValue(TagValueExpression.java:107)
at javax.faces.component.ComponentStateHelper.eval(ComponentStateHelper.java:190)
at javax.faces.component.ComponentStateHelper.eval(ComponentStateHelper.java:178)
at javax.faces.component.UIData.getValue(UIData.java:554)
at org.primefaces.component.datatable.DataTable.getValue(DataTable.java:867)
at org.primefaces.component.api.UIData.getDataModel(UIData.java:579)
at javax.faces.component.UIData.getRowCount(UIData.java:339)
at org.primefaces.component.api.UIData.calculateFirst(UIData.java:157)
at org.primefaces.component.datatable.DataTableRenderer.encodeMarkup(DataTableRenderer.java:176)
at org.primefaces.component.datatable.DataTableRenderer.encodeEnd(DataTableRenderer.java:82)
at javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:878)
at org.primefaces.renderkit.CoreRenderer.renderChild(CoreRenderer.java:63)
at org.primefaces.renderkit.CoreRenderer.renderChildren(CoreRenderer.java:47)
at org.primefaces.component.panel.PanelRenderer.encodeContent(PanelRenderer.java:202)
at org.primefaces.component.panel.PanelRenderer.encodeMarkup(PanelRenderer.java:119)
at org.primefaces.component.panel.PanelRenderer.encodeEnd(PanelRenderer.java:56)
at javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:878)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1620)
at javax.faces.render.Renderer.encodeChildren(Renderer.java:168)
at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:848)
at org.primefaces.renderkit.CoreRenderer.renderChild(CoreRenderer.java:59)
at org.primefaces.renderkit.CoreRenderer.renderChildren(CoreRenderer.java:47)
at org.primefaces.component.panel.PanelRenderer.encodeContent(PanelRenderer.java:202)
at org.primefaces.component.panel.PanelRenderer.encodeMarkup(PanelRenderer.java:119)
at org.primefaces.component.panel.PanelRenderer.encodeEnd(PanelRenderer.java:56)
at javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:878)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1620)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1616)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1616)
at com.sun.faces.application.view.FaceletViewHandlingStrategy.renderView(FaceletViewHandlingStrategy.java:380)
at com.sun.faces.application.view.MultiViewHandler.renderView(MultiViewHandler.java:126)
at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:127)
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:139)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:313)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.primefaces.webapp.filter.FileUploadFilter.doFilter(FileUploadFilter.java:79)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:501)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:950)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1040)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:607)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:315)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Caused by: org.hibernate.WrongClassException: Object with id: 3 was not of the specified subclass: br.com.wplex.cccw.bo.DadosDeCobrancaBO (loaded object was of wrong class class br.com.wplex.cccw.bo.ClienteBO)
at org.hibernate.loader.Loader.instanceAlreadyLoaded(Loader.java:1307)
at org.hibernate.loader.Loader.getRow(Loader.java:1260)
at org.hibernate.loader.Loader.getRowFromResultSet(Loader.java:619)
at org.hibernate.loader.Loader.doQuery(Loader.java:745)
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:270)
at org.hibernate.loader.Loader.loadCollection(Loader.java:2082)
at org.hibernate.loader.collection.CollectionLoader.initialize(CollectionLoader.java:62)
at org.hibernate.persister.collection.AbstractCollectionPersister.initialize(AbstractCollectionPersister.java:628)
at org.hibernate.event.def.DefaultInitializeCollectionEventListener.onInitializeCollection(DefaultInitializeCollectionEventListener.java:83)
at org.hibernate.impl.SessionImpl.initializeCollection(SessionImpl.java:1853)
at org.hibernate.collection.AbstractPersistentCollection.forceInitialization(AbstractPersistentCollection.java:479)
at org.hibernate.engine.StatefulPersistenceContext.initializeNonLazyCollections(StatefulPersistenceContext.java:899)
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:275)
at org.hibernate.loader.Loader.doList(Loader.java:2449)
at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2192)
at org.hibernate.loader.Loader.list(Loader.java:2187)
at org.hibernate.loader.hql.QueryLoader.list(QueryLoader.java:452)
at org.hibernate.hql.ast.QueryTranslatorImpl.list(QueryTranslatorImpl.java:363)
at org.hibernate.engine.query.HQLQueryPlan.performList(HQLQueryPlan.java:196)
at org.hibernate.impl.SessionImpl.list(SessionImpl.java:1258)
at org.hibernate.impl.QueryImpl.list(QueryImpl.java:102)
at br.com.wplex.cccw.dao.GerenciadorTransacoes.pesquise(GerenciadorTransacoes.java:450)
at br.com.wplex.cccw.dao.Dao.busca(Dao.java:69)
at br.com.wplex.cccw.dao.FrotaDao.listaDeFrotas(FrotaDao.java:43)
at br.com.wplex.cccw.regras.RegrasDeFrota.listaTodasAsFrotasCadastradas(RegrasDeFrota.java:204)
at br.com.wplex.cccw.mbean.FrotaMBean.getFrotas(FrotaMBean.java:130)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at javax.el.BeanELResolver.getValue(BeanELResolver.java:99)
at javax.el.CompositeELResolver.getValue(CompositeELResolver.java:67)
at com.sun.faces.el.FacesCompositeELResolver.getValue(FacesCompositeELResolver.java:72)
at org.apache.el.parser.AstValue.getValue(AstValue.java:183)
at org.apache.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:184)
at com.sun.faces.facelets.el.TagValueExpression.getValue(TagValueExpression.java:102)
... 53 more
29/05/2014 10:15:45 org.apache.catalina.core.StandardWrapperValve invoke
GRAVE: Servlet.service() for servlet [Faces Servlet] in context with path [/wplex3CW] threw exception [Object with id: 3 was not of the specified subclass: br.com.wplex.cccw.bo.DadosDeCobrancaBO (loaded object was of wrong class class br.com.wplex.cccw.bo.ClienteBO)] with root cause
org.hibernate.WrongClassException: Object with id: 3 was not of the specified subclass: br.com.wplex.cccw.bo.DadosDeCobrancaBO (loaded object was of wrong class class br.com.wplex.cccw.bo.ClienteBO)
at org.hibernate.loader.Loader.instanceAlreadyLoaded(Loader.java:1307)
at org.hibernate.loader.Loader.getRow(Loader.java:1260)
at org.hibernate.loader.Loader.getRowFromResultSet(Loader.java:619)
at org.hibernate.loader.Loader.doQuery(Loader.java:745)
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:270)
at org.hibernate.loader.Loader.loadCollection(Loader.java:2082)
at org.hibernate.loader.collection.CollectionLoader.initialize(CollectionLoader.java:62)
at org.hibernate.persister.collection.AbstractCollectionPersister.initialize(AbstractCollectionPersister.java:628)
at org.hibernate.event.def.DefaultInitializeCollectionEventListener.onInitializeCollection(DefaultInitializeCollectionEventListener.java:83)
at org.hibernate.impl.SessionImpl.initializeCollection(SessionImpl.java:1853)
at org.hibernate.collection.AbstractPersistentCollection.forceInitialization(AbstractPersistentCollection.java:479)
at org.hibernate.engine.StatefulPersistenceContext.initializeNonLazyCollections(StatefulPersistenceContext.java:899)
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:275)
at org.hibernate.loader.Loader.doList(Loader.java:2449)
at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2192)
at org.hibernate.loader.Loader.list(Loader.java:2187)
at org.hibernate.loader.hql.QueryLoader.list(QueryLoader.java:452)
at org.hibernate.hql.ast.QueryTranslatorImpl.list(QueryTranslatorImpl.java:363)
at org.hibernate.engine.query.HQLQueryPlan.performList(HQLQueryPlan.java:196)
at org.hibernate.impl.SessionImpl.list(SessionImpl.java:1258)
at org.hibernate.impl.QueryImpl.list(QueryImpl.java:102)
at br.com.wplex.cccw.dao.GerenciadorTransacoes.pesquise(GerenciadorTransacoes.java:450)
at br.com.wplex.cccw.dao.Dao.busca(Dao.java:69)
at br.com.wplex.cccw.dao.FrotaDao.listaDeFrotas(FrotaDao.java:43)
at br.com.wplex.cccw.regras.RegrasDeFrota.listaTodasAsFrotasCadastradas(RegrasDeFrota.java:204)
at br.com.wplex.cccw.mbean.FrotaMBean.getFrotas(FrotaMBean.java:130)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at javax.el.BeanELResolver.getValue(BeanELResolver.java:99)
at javax.el.CompositeELResolver.getValue(CompositeELResolver.java:67)
at com.sun.faces.el.FacesCompositeELResolver.getValue(FacesCompositeELResolver.java:72)
at org.apache.el.parser.AstValue.getValue(AstValue.java:183)
at org.apache.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:184)
at com.sun.faces.facelets.el.TagValueExpression.getValue(TagValueExpression.java:102)
at javax.faces.component.ComponentStateHelper.eval(ComponentStateHelper.java:190)
at javax.faces.component.ComponentStateHelper.eval(ComponentStateHelper.java:178)
at javax.faces.component.UIData.getValue(UIData.java:554)
at org.primefaces.component.datatable.DataTable.getValue(DataTable.java:867)
at org.primefaces.component.api.UIData.getDataModel(UIData.java:579)
at javax.faces.component.UIData.getRowCount(UIData.java:339)
at org.primefaces.component.api.UIData.calculateFirst(UIData.java:157)
at org.primefaces.component.datatable.DataTableRenderer.encodeMarkup(DataTableRenderer.java:176)
at org.primefaces.component.datatable.DataTableRenderer.encodeEnd(DataTableRenderer.java:82)
at javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:878)
at org.primefaces.renderkit.CoreRenderer.renderChild(CoreRenderer.java:63)
at org.primefaces.renderkit.CoreRenderer.renderChildren(CoreRenderer.java:47)
at org.primefaces.component.panel.PanelRenderer.encodeContent(PanelRenderer.java:202)
at org.primefaces.component.panel.PanelRenderer.encodeMarkup(PanelRenderer.java:119)
at org.primefaces.component.panel.PanelRenderer.encodeEnd(PanelRenderer.java:56)
at javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:878)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1620)
at javax.faces.render.Renderer.encodeChildren(Renderer.java:168)
at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:848)
at org.primefaces.renderkit.CoreRenderer.renderChild(CoreRenderer.java:59)
at org.primefaces.renderkit.CoreRenderer.renderChildren(CoreRenderer.java:47)
at org.primefaces.component.panel.PanelRenderer.encodeContent(PanelRenderer.java:202)
at org.primefaces.component.panel.PanelRenderer.encodeMarkup(PanelRenderer.java:119)
at org.primefaces.component.panel.PanelRenderer.encodeEnd(PanelRenderer.java:56)
at javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:878)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1620)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1616)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1616)
at com.sun.faces.application.view.FaceletViewHandlingStrategy.renderView(FaceletViewHandlingStrategy.java:380)
at com.sun.faces.application.view.MultiViewHandler.renderView(MultiViewHandler.java:126)
at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:127)
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:139)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:313)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.primefaces.webapp.filter.FileUploadFilter.doFilter(FileUploadFilter.java:79)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:501)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:950)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1040)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:607)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:315)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
可能是什么问题？