package Servicios;


public class Usuario implements Serializable{
  private String mail;
  private String pass;
  private String nick;

public Usuario(String mail,String pass){
    this.mail=mail;
    this.pass=pass;
}
public Usuario(String mail,String pass,String nick){
    this.mail=mail;
    this.pass=pass;
    this.nick=nick;
}


public String getMail() {
    return mail;
}
public void setMail(String mail) {
    this.mail = mail;
}
public String getPass() {
    return pass;
}
public void setPass(String pass) {
    this.pass = pass;
}
public String getNick() {
    return nick;
}
public void setNick(String nick) {
    this.nick = nick;
}

<?xml version="1.0" encoding="UTF-8"?>
      <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
        <hibernate-mapping>
    <class name="Servicios.Usuario" table="Usuario" >
    <id column="mail" name="mail" />
    <property  name="pass" column="pass"/>
    <property  name="nick" column="nick" />
    </class>
   </hibernate-mapping>

package Servicios;

 import org.hibernate.Session;
 import org.hibernate.SessionFactory;
 import org.hibernate.cfg.Configuration;
 import org.hibernate.service.ServiceRegistry;
 import org.hibernate.service.ServiceRegistryBuilder;

  public class Main {

  public static void main(String[] args) {
      SessionFactory sessionFactory;

    Configuration configuration = new Configuration().configure();

    ServiceRegistry serviceRegistry = new ServiceRegistryBuilder().applySettings(configuration.getProperties()).buildServiceRegistry();
    sessionFactory = configuration.buildSessionFactory(serviceRegistry);

    Usuario user=new Usuario("jose@gmail.com","1234");

    Session session = sessionFactory.openSession();
    session.beginTransaction();

    session.save(user);
    session.getTransaction().commit();
    session.close();
}
}