Como Utilizar o Hibernate sem o XML?

package sga.hibernate.configurations;
/*
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 * and open the template in the editor.
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import java.util.List;
import javax.swing.JOptionPane;
import org.hibernate.HibernateException;
import org.hibernate.Transaction;

/**
 *
 * @author Juan Perondi
 */
public class GenericDAO<Objeto> {

    private Objeto objeto;
    //public final Session session;
    Transaction transacao;

    public GenericDAO() {
        transacao = HibernateUtil.getSession().beginTransaction();
    }

    public void salvaOuAtualiza() {
        try {
            HibernateUtil.getSession().clear();
            HibernateUtil.getSession().saveOrUpdate(objeto);
            transacao.commit();
        } catch (HibernateException erro) {
            erro.printStackTrace();
            transacao.rollback();
        }
    }

    public void exclui() {
        try {
            HibernateUtil.getSession().delete(objeto);
            transacao.commit();
        } catch (HibernateException erro) {
            JOptionPane.showMessageDialog(null, "Erro na exclusao:  " + erro);
            transacao.rollback();
        }
    }

    public void setObject(Objeto objeto) {
        clearObject();
        this.objeto = objeto;
    }

    void clearObject() {
        objeto = null;
    }
}

import java.io.IOException;
import java.sql.Connection;
import java.util.Scanner;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.JOptionPane;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.AnnotationConfiguration;
import org.hibernate.tool.hbm2ddl.SchemaExport;

public class HibernateUtil {

    private static SessionFactory sessionFactory;
    private static Session session;
    private static Connection connection;

    static {
        try {
            sessionFactory = getConfiguration().buildSessionFactory();//nao precisa do .configure, pois nao temos xml
            openSession();
        } catch (Exception erro) {
            JOptionPane.showMessageDialog(null, "Erro: " + erro);
            sessionFactory = null;
        }
    }

    public static Session getSession() {
        session.clear();
        return session;
    }

    private static AnnotationConfiguration getConfiguration() {
        return new AnnotationConfiguration()
                .addAnnotatedClass(sga.hibernate.mapeamento.Academico.class);// aqui voce coloca a sua classe mapeada, se for na pasta raiz basta coloocar o nome da sua class.class
    }

    private static void openSession() {
        session = sessionFactory.openSession();
    }

    public static void eraseDatabase() { //cria o BD a partir das Annotations!
        SchemaExport se = new SchemaExport(getConfiguration());
        se.create(true, true);
    }
}

us_Usuario objUsuario = new us_Usuario();  
        objUsuario.setUsu_login("Ricardo");  
        objUsuario.setUsu_senha("123");  

        GenericDAO dao = new GenericDAO();
        dao.setObject(objUsuario);
        dao.salvaOuAtualiza();

cfg.configure();  //o metodo configure busca na raiz do projeto o XML de configuracao, no caso de quem usa annotations tem que fazer assim:

cfg.addAnnotationConfiguration(caminho.ate.a.classe.class);//como se fosse /Caminho/ate/a/classe.class, se esta na raiz basta colocar classe.class

// RELACIONAMENTO COM O IDIOMA.
           us_Idioma objIdioma      = new us_Idioma();
           objIdioma.setIdi_descricao("INGLES");

           GenericDAO dao   = new GenericDAO();
           dao.setObject(objIdioma);
           dao.salvaOuAtualiza();

        // RELACIONAMENTO COM O GRUPO.
           us_Grupo  objGrupo       = new us_Grupo();
           objGrupo.setGru_descricao("ADMINISTRADOR");

           //GenericDAO dao   = new GenericDAO();
           dao.setObject(objGrupo);
           dao.salvaOuAtualiza();

           // Salvando na Tabela de Usuarios.
           us_Usuario objUsuario    = new us_Usuario();

           objUsuario.setUsu_login("Eliane Camargo");
           objUsuario.setUsu_senha("123");
           objUsuario.setIdioma(objIdioma);
           objUsuario.setGrupo(objGrupo);

           dao.setObject(objUsuario);
           dao.salvaOuAtualiza();

private static AnnotationConfiguration getConfiguration() {
        return new AnnotationConfiguration()
                .addAnnotatedClass(us_Usuario.class);// aqui voce coloca a sua classe mapeada, se for na pasta raiz basta coloocar o nome da sua class.class
    }

private static AnnotationConfiguration getConfiguration() {
        return new AnnotationConfiguration()
                .addAnnotatedClass(COLOCAR AQUI A CLASSE CADA VEZ QUE FOR SALVAR ???  .class);// aqui voce coloca a sua classe mapeada, se for na pasta raiz basta coloocar o nome da sua class.class
    }

public class DAO {
	private static ThreadLocal<Session> threadlocal = new ThreadLocal<Session>();
	private static SessionFactory sessionfactory = new AnnotationConfiguration().configure().buildSessionFactory();
	
	public static Session getSession(){
		Session session = threadlocal.get();
		if (session==null) {
			session = sessionfactory.openSession();
			threadlocal.set(session);
		}
		return session;
	}
public void begin(){
		getSession().beginTransaction();
	}
	
	public void commit(){
		getSession().getTransaction().commit();
	}
	
	public void rollback(){
		getSession().getTransaction().rollback();
	}
	
	public void close(){
		getSession().clear();
		threadlocal.set(null);
	}
}

public class UsuarioDAO extends DAO {

public void excluir(Usuario us) {
		begin();
		getSession().delete(us);
		commit();
	}

run:
log4j:WARN No appenders could be found for logger (org.hibernate.cfg.annotations.Version).
log4j:WARN Please initialize the log4j system properly.
Exception in thread "AWT-EventQueue-0" org.hibernate.MappingException: Unknown entity: Classes.us_Usuario
        at org.hibernate.impl.SessionFactoryImpl.getEntityPersister(SessionFactoryImpl.java:550)
        at org.hibernate.impl.SessionImpl.getEntityPersister(SessionImpl.java:1338)
        at org.hibernate.event.def.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:98)
        at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:187)
        at org.hibernate.event.def.DefaultSaveEventListener.saveWithGeneratedOrRequestedId(DefaultSaveEventListener.java:33)
        at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:172)
        at org.hibernate.event.def.DefaultSaveEventListener.performSaveOrUpdate(DefaultSaveEventListener.java:27)
        at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:70)
        at org.hibernate.impl.SessionImpl.fireSave(SessionImpl.java:535)
        at org.hibernate.impl.SessionImpl.save(SessionImpl.java:523)
        at org.hibernate.impl.SessionImpl.save(SessionImpl.java:519)
        at Hibernate.UsuarioDAO.excluir(UsuarioDAO.java:19)
        at Formularios.FConfiguracoes.jButton4ActionPerformed(FConfiguracoes.java:497)
        at Formularios.FConfiguracoes.access$1000(FConfiguracoes.java:37)
        at Formularios.FConfiguracoes$11.actionPerformed(FConfiguracoes.java:325)
        at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1995)
        at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2318)
        at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:387)
        at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:242)
        at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:236)
        at java.awt.Component.processMouseEvent(Component.java:6038)
        at javax.swing.JComponent.processMouseEvent(JComponent.java:3260)
        at java.awt.Component.processEvent(Component.java:5803)
        at java.awt.Container.processEvent(Container.java:2058)
        at java.awt.Component.dispatchEventImpl(Component.java:4410)
        at java.awt.Container.dispatchEventImpl(Container.java:2116)
        at java.awt.Component.dispatchEvent(Component.java:4240)
        at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4322)
        at java.awt.LightweightDispatcher.processMouseEvent(Container.java:3986)
        at java.awt.LightweightDispatcher.dispatchEvent(Container.java:3916)
        at java.awt.Container.dispatchEventImpl(Container.java:2102)
        at java.awt.Window.dispatchEventImpl(Window.java:2429)
        at java.awt.Component.dispatchEvent(Component.java:4240)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
        at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:273)
        at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:183)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:173)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:168)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:160)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:121)
BUILD SUCCESSFUL (total time: 8 seconds)

// Salvando na Tabela de Usuarios.
           us_Usuario objUsuario    = new us_Usuario();

           objUsuario.setUsu_login("Eliane Camargo");
           objUsuario.setUsu_senha("123");
           //objUsuario.setIdioma(objIdioma);
           //objUsuario.setGrupo(objGrupo);

           UsuarioDAO usuario   = new UsuarioDAO();
           usuario.excluir(objUsuario);

public class UsuarioDAO extends GenericDAO{

    private static final Long serialVersionUID = 1L;
    private Session session;



    public UsuarioDAO(Session session){
        this.session = session;
    }

    public UsuarioDAO(){
        this.session = getSession();
    }


    // Regra de Negocios    : Salvando o Usuario.
    public Long InclUsuario(us_Usuario us){
        Session ses = getSession();
        ses.save(us);
        ses.getTransaction().commit();
        ses.close();
        return us.getUsu_codigo();
    }

   // E so implementar as Transacoes Restantes Tipo, Altera, Excluir etc...

public class HibernateUtil
{
   private static final Long serialVersionUID = 1L;
   private static   HibernateUtil   me;
   private          SessionFactory  sessionFactory;

   //Construtor Padrao.
   private HibernateUtil()
   {
       sessionFactory = new AnnotationConfiguration()

            .setProperty("hibernate.connection.url","jdbc:postgresql://localhost:5433/GsAdm")
            .setProperty("hibernate.connection.driver_class", "org.postgresql.Driver")
            .setProperty("hibernate.connection.username", "postgres")
            .setProperty("hibernate.connection.password","postgres")
            .setProperty("hibernate.dialect","org.hibernate.dialect.PostgreSQLDialect")
            .setProperty("hibernate.format_sql","true")
            .setProperty("hibernate.pool_size", "10")
            .setProperty("hibernate.hbm2ddl.auto ", "create")

            // Adcionar as Classes Mapeadas.
            .addAnnotatedClass(us_Usuario.class)
            .addAnnotatedClass(us_Grupo.class)
            .addAnnotatedClass(us_Idioma.class)
            .buildSessionFactory();
    }


   // Pegar a Sessao no Hibernate.
   public Session getSession()
    {
       Session toReturn = sessionFactory.openSession();
       toReturn.beginTransaction();
       return toReturn;
   }

   // Pegar ums Instancia no Hibernate.
   public static HibernateUtil getInstance()
    {
       if(me == null)
       {
           me = new HibernateUtil();
       }

       return me;
   }
}

public abstract  class GenericDAO
{

    private static final Long serialversionUID = 1L;

    // Construtor Padrao.
    public GenericDAO() {

    }

        protected Session getSession()
        {
            return HibernateUtil.getInstance().getSession();
        }

        // Criando um Salvar Generico.
        public void SalvarPojo(Serializable pojo){

            // Instanciando a Sessao, Inicializando a Sessao.
            Session ses = getSession();

            ses.save(pojo);
            ses.getTransaction().commit();
            ses.close();
        }

        //
        protected <T extends  Serializable> T getPojo(Class<T> classToSearch, Serializable key){
            Session ses = getSession();
            Serializable toReturn = (Serializable) ses.get(classToSearch, key);
            ses.getTransaction().commit();
            ses.close();
                return (T) toReturn;
        }

        // Removendo o Pojo.
        protected  void removePojo(Serializable pojoToRemove){
            Session ses = getSession();
            ses.delete(pojoToRemove);
            ses.getTransaction().commit();
            ses.close();
        }



        protected Serializable getPurePojo(String query, Object... params){
            Session ses = getSession();

            Query qr = ses.createQuery(query);

            for(int i = 1; i <= params.length; i++){
                qr.setParameter(i, params[i-1]);
            }

            Object toReturn = qr.uniqueResult();

            ses.getTransaction().commit();
            ses.close();

            return (Serializable) toReturn;
        }




}

// Instanciando o Usuario.
            us_Usuario usuario = new us_Usuario();

           // Populando o Usuario.
            usuario.setUsu_nome("RICARDO");
            usuario.setUsu_senha("RICK");

            // Utilizando DAO Generico para Salvar os Dados.
            UsuarioDAO usDAO = new UsuarioDAO();

            usDAO.InclUsuario(usuario);