关于Hibernate出错的问题，请教高手……谢谢了

部分代码如下：
Cservlet.java

import java.io.IOException;

import java.io.PrintWriter;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import org.hibernate.Session;

import org.hibernate.SessionFactory;

import org.hibernate.cfg.Configuration;

import com.mmc.model.CBean;



public class Cservlet extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response)

			throws ServletException, IOException {		

		response.setContentType("text/html");

		PrintWriter out = response.getWriter();

		

		CBean c = new CBean();		

		System.out.println("在servelet中");

		int id = Integer.parseInt(request.getParameter("id"));

		String name = request.getParameter("name");

		String title = request.getParameter("title");



		c.setID(id);

		c.setName(name);

		

		Configuration cfg = new Configuration();

		SessionFactory sf = cfg.configure().buildSessionFactory();

		Session session = sf.openSession();

		session.beginTransaction();

		

		session.saveOrUpdate(c);

		session.getTransaction().commit();

		session.close();

		sf.close();		

	}



	public void doPost(HttpServletRequest request, HttpServletResponse response)

			throws ServletException, IOException {

		doGet(request, response);

	}

}

CBean.hbm.xml

……

<hibernate-mapping package="com.mmc.model">

	<class name="CBean" table="m"> 

        <id name="ID" column="id"> </id>

            <property name="name"></property>

    </class>

</hibernate-mapping>

hibernate.cfg.xml

<session-factory>

        <!-- Database connection settings -->

        <property name="connection.driver_class">com.mysql.jdbc.Driver</property>

        <property name="connection.url">jdbc:mysql://localhost/a</property>

        <property name="connection.username">root</property>

        <property name="connection.password">123</property>



        <!-- JDBC connection pool (use the built-in) -->

        <property name="connection.pool_size">1</property>



        <!-- SQL dialect -->

        <property name="dialect">org.hibernate.dialect.MySQLDialect</property>



        <!-- Enable Hibernate's automatic session context management -->

        <property name="current_session_context_class">thread</property>



        <!-- Disable the second-level cache  -->

        <property name="cache.provider_class">org.hibernate.cache.NoCacheProvider</property>



        <!-- Echo all executed SQL to stdout -->

        <property name="show_sql">true</property>

        <property name="format_sql">true</property>



        <!-- Drop and re-create the database schema on startup -->

        <property name="hbm2ddl.auto">update</property>



         <mapping resource="com/mmc/model/CBean.hbm.xml"/>    

        <!--<mapping class="com.mmc.model.DBean"/> -->



    </session-factory>

运行后，出现错误如下：
严重: Servlet.service() for servlet Cservlet threw exception
java.util.ServiceConfigurationError: org.hibernate.integrator.spi.Integrator: Provider org.hibernate.envers.event.EnversIntegrator not found
at java.util.ServiceLoader.fail(ServiceLoader.java:214)
at java.util.ServiceLoader.access$400(ServiceLoader.java:164)
at java.util.ServiceLoader$LazyIterator.next(ServiceLoader.java:350)
at java.util.ServiceLoader$1.next(ServiceLoader.java:421)
at org.hibernate.service.classloading.internal.ClassLoaderServiceImpl.loadJavaServices(ClassLoaderServiceImpl.java:251)
at org.hibernate.integrator.internal.IntegratorServiceImpl.<init>(IntegratorServiceImpl.java:51)
at org.hibernate.service.internal.BootstrapServiceRegistryImpl.<init>(BootstrapServiceRegistryImpl.java:80)
at org.hibernate.service.internal.BootstrapServiceRegistryImpl.<init>(BootstrapServiceRegistryImpl.java:57)
at org.hibernate.service.ServiceRegistryBuilder.<init>(ServiceRegistryBuilder.java:76)
at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1746)
at Cservlet.doGet(Cservlet.java:43)
at Cservlet.doPost(Cservlet.java:57)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
at org.apache.coyote.http11.Http11AprProcessor.process(Http11AprProcessor.java:864)
at org.apache.coyote.http11.Http11AprProtocol$Http11ConnectionHandler.process(Http11AprProtocol.java:579)
at org.apache.tomcat.util.net.AprEndpoint$Worker.run(AprEndpoint.java:1665)
at java.lang.Thread.run(Thread.java:619)
走到

SessionFactory sf = cfg.configure().buildSessionFactory();

这里出错的……

请教各位高手们了，，谢谢……