public class SessionFactory {

    private static String CONFIG_FILE_LOCATION = "/hibernate.cfg.xml";

    private static final ThreadLocal threadLocal = new ThreadLocal();

    private static final Configuration cfg = new Configuration();

    private static net.sf.hibernate.SessionFactory sessionFactory;

    public static Session currentSession() throws HibernateException {
        Session session = (Session) threadLocal.get();

        if (session == null) {
            if (sessionFactory == null) {
                try {
                    cfg.configure(CONFIG_FILE_LOCATION);
                    sessionFactory = cfg.buildSessionFactory();
                }
                catch (Exception e) {
                    System.err.println("%%%% Error Creating SessionFactory %%%%");
                    e.printStackTrace();
                }
            }
            session = sessionFactory.openSession();  //就是这句！
            threadLocal.set(session);
        }

        return session;
    }

    public static void closeSession() throws HibernateException {
        Session session = (Session) threadLocal.get();
        threadLocal.set(null);

        if (session != null) {
            session.close();
        }
    }

    private SessionFactory() {
    }

}

2个例子都出现这个错，我用的MYECLIPSE 4.2,Hibernate 2。session = sessionFactory.openSession();这句有什么玄机吗？

java.lang.NullPointerException
com.nscorp.hibernate.SessionFactory.currentSession(SessionFactory.java:31)
com.nscorp.hibernate.VipService.getVipdataList(VipService.java:200)
org.apache.jsp.AddVipData_jsp._jspService(AddVipData_jsp.java:120)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:94)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:324)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:292)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:236)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)