如何在没有spring配置的情况下自动连接SessionFactory

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;

public class HibernateUtil {
    private static final SessionFactory sessionFactory;

    static {
        try {
            // 读取Hibernate配置文件
            Configuration configuration = new Configuration().configure();
            // 创建SessionFactory对象
            sessionFactory = configuration.buildSessionFactory();
        } catch (Throwable ex) {
            throw new ExceptionInInitializerError(ex);
        }
    }

    public static Session getSession() {
        return sessionFactory.openSession();
    }
}

public class UserDao {
    public void save(User user) {
        Session session = HibernateUtil.getSession();
        session.beginTransaction();
        session.save(user);
        session.getTransaction().commit();
        session.close();
    }
}

public class Main {
    public static void main(String[] args) {
        UserDao userDao = new UserDao();
        User user = new User();
        // 设置用户属性
        userDao.save(user);
    }
}