I am getting this error:-

log4j:WARN No appenders could be found for logger (org.hibernate.cfg.annotations.Version).
log4j:WARN Please initialize the log4j system properly.
Aug 15, 2014 5:19:46 PM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet UserController threw exception
java.lang.ClassNotFoundException: com.dev.beans.PatientDetailsHibernate
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1680)
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1526)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Unknown Source)
at org.hibernate.util.ReflectHelper.classForName(ReflectHelper.java:123)
at org.hibernate.cfg.AnnotationConfiguration.parseMappingElement(AnnotationConfiguration.java:647)
at org.hibernate.cfg.Configuration.parseSessionFactory(Configuration.java:1589)
at org.hibernate.cfg.Configuration.doConfigure(Configuration.java:1568)
at org.hibernate.cfg.AnnotationConfiguration.doConfigure(AnnotationConfiguration.java:1047)
at org.hibernate.cfg.AnnotationConfiguration.doConfigure(AnnotationConfiguration.java:64)
at org.hibernate.cfg.Configuration.doConfigure(Configuration.java:1542)
at org.hibernate.cfg.AnnotationConfiguration.doConfigure(AnnotationConfiguration.java:1035)
at org.hibernate.cfg.AnnotationConfiguration.doConfigure(AnnotationConfiguration.java:64)
at org.hibernate.cfg.Configuration.configure(Configuration.java:1462)
at org.hibernate.cfg.AnnotationConfiguration.configure(AnnotationConfiguration.java:1017)
at org.hibernate.cfg.AnnotationConfiguration.configure(AnnotationConfiguration.java:64)
at org.hibernate.cfg.Configuration.configure(Configuration.java:1448)
at org.hibernate.cfg.AnnotationConfiguration.configure(AnnotationConfiguration.java:1011)
at com.dev.Service.UserService.addpatienDetail(UserService.java:45)
at com.dev.controller.UserController.doPost(UserController.java:268)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:643)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:723)
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:103)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:861)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:606)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
at java.lang.Thread.run(Unknown Source)

Initial SessionFactory creation failed.org.hibernate.MappingException: Unable to load class declared as <mapping class="com.dev.beans.PatientDetailsHibernate"/> in the configuration:

UTILITY CLASS IS :-

public class HibernateUtility
{
private static final SessionFactory sessionFactory;

static {
try {

// Create the SessionFactory from standard (hibernate.cfg.xml)
// config file.
sessionFactory = new AnnotationConfiguration().configure()
.buildSessionFactory();
} catch (Throwable ex) {
// Log the exception.
System.err.println("Initial SessionFactory creation failed." + ex);
throw new ExceptionInInitializerError(ex);
}
}

public static SessionFactory getSessionFactory() {
return sessionFactory;
}

public static Session beginTransaction() {
Session hibernateSession = HibernateUtility.getSession();
hibernateSession.beginTransaction();
return hibernateSession;
}

public static void commitTransaction() {
HibernateUtility.getSession().getTransaction().commit();
}

public static void rollbackTransaction() {
HibernateUtility.getSession().getTransaction().rollback();
}

public static void closeSession() {
HibernateUtility.getSession().close();
}

public static Session getSession() {
Session hibernateSession = sessionFactory.getCurrentSession();
return hibernateSession;
}


hibernate.cfg.xml is:-

<hibernate-configuration>
<session-factory>

<property name="hibernate.dialect">
org.hibernate.dialect.OracleDialect
</property>
<property name="hibernate.connection.driver_class">
oracle.jdbc.driver.OracleDriver
</property>

<property name="hibernate.connection.url">
jdbc:oracle:thin:@localhost:1521:xe
</property>
<property name="hibernate.connection.username">
system
</property>
<property name="hibernate.connection.password">
sys
</property>
<property name="hibernate.current_session_context_class">thread</property>


<mapping class="com.dev.beans.PatientDetailsHibernate"></mapping>

</session-factory>
</hibernate-configuration>

and the service class is


public PatientDetailsHibernate addpatienDetail(PatientDetailsHibernate pd) throws SQLException, IOException
{

try
{
SessionFactory sessionFactory = new AnnotationConfiguration().configure().buildSessionFactory();
Session hibernateSession = sessionFactory.getCurrentSession();
hibernateSession.beginTransaction();

hibernateSession.save(pd);
hibernateSession.getTransaction().commit();

System.out.println("session = "+hibernateSession);
System.out.println("in hibernate");
if(hibernateSession.isOpen())
hibernateSession.close();

System.out.println("session = "+hibernateSession);

}

can anyone tell me where i am doing wrong.