Session session = HibernateUtil.beginTransaction(); 		
   try {
			Main u = new Main();
			u.setPassword("abc123");
			session.saveOrUpdate(u);
		} finally {
			HibernateUtil.commitTransaction();
		}

  // class HibernateUtil {
	public static Session beginTransaction() {
		Session hibernateSession;
		hibernateSession = HibernateUtil.getSession();
		hibernateSession.beginTransaction();
		return hibernateSession;
	}







package dao;

import main.Main;// пакет с DAO

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.AnnotationConfiguration;
import org.hibernate.cfg.Configuration;
import org.hibernate.tool.hbm2ddl.SchemaExport;

public class HibernateUtil {
	private static SessionFactory factory;

	public static Configuration getInitializedConfiguration() {
		AnnotationConfiguration config = new AnnotationConfiguration();
		/* !!!!!!!!!!!!!!   // пакет с DAO */
		config.addAnnotatedClass(Book.class);
		config.addAnnotatedClass(Autor.class);
		config.configure();
		return config;
	}

	public static Session getSession() {
		if (factory == null) {
			Configuration config = HibernateUtil.getInitializedConfiguration();
			factory = config.buildSessionFactory();
		}
		Session hibernateSession = factory.getCurrentSession();
		return hibernateSession;
	}

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

	public static void recreateDatabase() {
		Configuration config;
		config = HibernateUtil.getInitializedConfiguration();
		new SchemaExport(config).create(true, true);
	}

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

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

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

	public static void main(String args[]) {
		HibernateUtil.recreateDatabase();
	}

}