Hibernate C3P0 错误

java.lang.NullPointerException
at com.mchange.v2.c3p0.stmt.GooGooStatementCache.keyRec(GooGooStatementCache.java:484)
at com.mchange.v2.c3p0.stmt.GooGooStatementCache.checkoutQueue(GooGooStatementCache.java:504)
at com.mchange.v2.c3p0.stmt.GooGooStatementCache.checkoutStatement(GooGooStatementCache.java:84)
at com.mchange.v2.c3p0.impl.NewPooledConnection.checkoutStatement(NewPooledConnection.java:168)
at com.mchange.v2.c3p0.impl.NewProxyConnection.prepareStatement(NewProxyConnection.java:185)
at org.hibernate.jdbc.AbstractBatcher.getPreparedStatement(AbstractBatcher.java:497)
at org.hibernate.jdbc.AbstractBatcher.prepareStatement(AbstractBatcher.java:94)
at org.hibernate.jdbc.AbstractBatcher.prepareStatement(AbstractBatcher.java:87)
at org.hibernate.jdbc.AbstractBatcher.prepareBatchStatement(AbstractBatcher.java:218)
at org.hibernate.persister.entity.AbstractEntityPersister.update(AbstractEntityPersister.java:2304)
at org.hibernate.persister.entity.AbstractEntityPersister.updateOrInsert(AbstractEntityPersister.java:2257)
at org.hibernate.persister.entity.AbstractEntityPersister.update(AbstractEntityPersister.java:2557)
at org.hibernate.action.EntityUpdateAction.execute(EntityUpdateAction.java:92)
at org.hibernate.engine.ActionQueue.execute(ActionQueue.java:248)
at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:232)
at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:140)
at org.hibernate.event.def.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:298)
at org.hibernate.event.def.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:27)
at org.hibernate.impl.SessionImpl.flush(SessionImpl.java:1000)
at org.hibernate.impl.SessionImpl.managedFlush(SessionImpl.java:338)
at org.hibernate.transaction.JDBCTransaction.commit(JDBCTransaction.java:106)
at dao.impl.UserDaoImpl.updateUser(UserDaoImpl.java:74)
at biz.impl.UserBizImpl.Update(UserBizImpl.java:40)
at action.UserAction.Update(UserAction.java:95)
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:274)
at org.apache.struts.actions.DispatchAction.execute(DispatchAction.java:194)
at org.apache.struts.actions.MappingDispatchAction.execute(MappingDispatchAction.java:169)
at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:419)
at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:224)
at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1194)
at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:432)
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:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:286)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)
at java.lang.Thread.run(Thread.java:595)在update的时候出现异常,请各位高手帮忙解决,谢谢!~~