net.sf.hibernate.MappingException: could not instantiate id generator

[Nagendra Batchu]

Hi,
i am new to Hibernate.
I am trying to get the current session from the HibernateSessionFactory. I am getting following exception.
Could any one kindly help me in this?
%%%% Error Creating SessionFactory %%%%
net.sf.hibernate.MappingException: could not instantiate id generator
at net.sf.hibernate.id.IdentifierGeneratorFactory.create(IdentifierGeneratorFactory.java:82)
at net.sf.hibernate.mapping.SimpleValue.createIdentifierGenerator(SimpleValue.java:82)
at net.sf.hibernate.persister.AbstractEntityPersister.<init>(AbstractEntityPersister.java:644)
at net.sf.hibernate.persister.EntityPersister.<init>(EntityPersister.java:690)
at net.sf.hibernate.persister.PersisterFactory.createClassPersister(PersisterFactory.java:42)
at net.sf.hibernate.impl.SessionFactoryImpl.<init>(SessionFactoryImpl.java:137)
at net.sf.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:805)
at com.rm.juno.chequepayments.HibernateSessionFactory.currentSession(HibernateSessionFactory.java:50)
at com.rm.juno.chequepayments.server.dao.ChequePaymentsHibernateDAO.fetchTransactionListForChqPrinting(ChequePaymentsHibernateDAO.java:334)
at com.rm.juno.chequepayments.server.br.ChequePaymentsBaseBR.fetchTransactionListForChqPrinting(ChequePaymentsBaseBR.java:1063)
at com.rm.juno.chequepayments.server.br.ChequePaymentsBaseBR.fetchDataChqForPrintingTab(ChequePaymentsBaseBR.java:831)
at com.rm.juno.chequepayments.server.stub.ChequePaymentsStub.fetchDataChqForPrintingTab(ChequePaymentsStub.java:181)
at com.rm.juno.chequepayments.web.delegate.ChequePaymentsDelegate.fetchDataChqForPrintingTab(ChequePaymentsDelegate.java:141)
at com.rm.juno.chequepayments.web.action.ChequePaymentsAction.processShowChequesForPrinting(ChequePaymentsAction.java:546)
at com.rm.juno.chequepayments.web.action.ChequePaymentsAction.showChequesForPrinting(ChequePaymentsAction.java:525)
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:585)
at org.apache.struts.actions.DispatchAction.dispatchMethod(DispatchAction.java:269)
at org.apache.struts.actions.DispatchAction.execute(DispatchAction.java:170)
at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:425)
at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:228)
at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1913)
at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:462)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:710)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:269)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
at com.rm.juno.JunoFilter.doFilter(JunoFilter.java:140)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:215)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:174)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:117)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:108)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:174)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:874)
at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:665)
at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:528)
at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:81)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:689)
at java.lang.Thread.run(Thread.java:595)
Caused by: java.lang.ClassNotFoundException:
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:164)
at net.sf.hibernate.util.ReflectHelper.classForName(ReflectHelper.java:102)
at net.sf.hibernate.id.IdentifierGeneratorFactory.create(IdentifierGeneratorFactory.java:76)
... 43 more

thanks in advance for help.

[Paul Sturrock]

Why are you using Hibernate 2? Its very old.

[Nagendra Batchu]

I am currently working on hibernate POC. I am trying to convert one of the our existing module to use hibernate.
I am just taking the help from following examples http://www.laliluna.de/struts-hibernate-integration-tutorial-en.html.

Cann't we proceed with hibernate2? Is this error is specific to version?


thanks.

[Paul Sturrock]

The error you are seeing is a ClassNotFoundException, so its not specific to Hibernate2, it happens when the ClassLoader tries to load a class throuhg its string name and the class is not on the classpath.

The tutorial you are using uses Hibernate3. Hibernate2 is very old, which is no reason in itself not to use it (though its is not nearly as feature rich as Hibernate3), however one significant change from 2 to 3 is a wholesale refactoring of the package structure. So the class names and the mappings shown in that tutorial will not work with Hibernate2. If you are looking to learn Hibernate, learn the latest version.

[Nagendra Batchu]

Thanks Paul.

Thanks for your information.
I am still in initial stage of my work (POC). So, let me change the version now itself and see whether this error still persist.!!!

Could you suggest any site or technical stuff related to steps involved in incorporating hibernate into existing project(module)?

Any related information would be great helpful.

thanks a lot.

[Paul Sturrock]

Nothing springs to mind. I would recommend learning Hibernate in isolation before trying to integrate. But assuming your existing application has a DAO layer it should be fairly simple to swap one persistance technology for another.