调用hibernate操作报异常求解

项目中有个Action~
当在Action初始化的时候new一个ServiceManage就会报异常
ServiceManage:package com.guangguang.service;import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
import com.guangguang.model.User;public class ServiceManage {
static Configuration cfg = new Configuration();
static SessionFactory sf= cfg.configure().buildSessionFactory();
static Session session = sf.openSession();

public void begin(){
session.beginTransaction();
}
public void end(){
session.getTransaction().commit();
session.close();
sf.close();
}
public void add(User u){
begin();
session.save(u);
end();
}

public void delete(User u){
begin();
session.delete(u);
end();
}

public void update(User u){
begin();
session.update(u);
end();
}

public void load(User u){
begin();
session.load(u ,u.getClass());
end();
}
}
异常信息:严重: Servlet.service() for servlet default threw exception
java.lang.ClassNotFoundException: org.hibernate.Session
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1358)
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1204)
at java.lang.ClassLoader.loadClassInternal(Unknown Source)
at com.guangguang.action.RegisterAction.<init>(RegisterAction.java:14)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
at java.lang.Class.newInstance0(Unknown Source)
at java.lang.Class.newInstance(Unknown Source)
at com.opensymphony.xwork2.ObjectFactory.buildBean(ObjectFactory.java:119)
at com.opensymphony.xwork2.ObjectFactory.buildBean(ObjectFactory.java:150)
at com.opensymphony.xwork2.ObjectFactory.buildBean(ObjectFactory.java:139)
at com.opensymphony.xwork2.ObjectFactory.buildAction(ObjectFactory.java:109)
at com.opensymphony.xwork2.DefaultActionInvocation.createAction(DefaultActionInvocation.java:288)
at com.opensymphony.xwork2.DefaultActionInvocation.init(DefaultActionInvocation.java:388)
at com.opensymphony.xwork2.DefaultActionProxy.prepare(DefaultActionProxy.java:187)
at org.apache.struts2.impl.StrutsActionProxy.prepare(StrutsActionProxy.java:61)
at org.apache.struts2.impl.StrutsActionProxyFactory.createActionProxy(StrutsActionProxyFactory.java:39)
at com.opensymphony.xwork2.DefaultActionProxyFactory.createActionProxy(DefaultActionProxyFactory.java:47)
at org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:478)
at org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:77)
at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:91)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
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:263)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:584)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)
at java.lang.Thread.run(Unknown Source)
环境是:
JDK6.0  struts2.1.6 hibernate3.3.2我觉得问题出在hibernate内部了
但是是怎么回事,我也不知道`请有过类似问题的高手指点一下`
还需要什么信息请留言..