How can i choose which oracle db to connect on run time as per user choice ?

public final class DataSourceUtil {
    private DataSourceUtil() {

    }
   // NOTE: this "String name" is name of hibernate.cfg.xml with hibernate configuration
    public static SessionFactory getDataSource(String name) {
        final ServiceRegistry registry =
                new StandardServiceRegistryBuilder().configure(name).build();
        return new MetadataSources(registry).buildMetadata().buildSessionFactory();
    }

}

public class Application {
    // not final anymore, because can be changed, but static,
    // because we use it in `main`
    private static SessionFactory session;

    public static void main(String[] args) {
        // prompt user for input
        // I put here hibernate.cfg.xml as argument. You can use what user picked
        session = DataSourceUtil.getDataSource("hibernate.cfg.xml");
        // do stuff
        Contact contact1 = new ContactBuilder("John","Doe")
                            .withEmail("john@verizon.net")
                            .withPhone(2222277018L)
                            .build();
        save(contact1);
        System.out.println("This is before the update:");
        getContacts().forEach(System.out::println);
        // close session
        session.close();

        // prompt user for another input
       // I put here hibernate2.cfg.xml as argument. You can use what user picked
        session = DataSourceUtil.getDataSource("hibernate2.cfg.xml");
        // do stuff
        Contact contact2 = new ContactBuilder("John","Doe")
                .withEmail("john@verizon.net")
                .withPhone(2222277018L)
                .build();
        save(contact2);
        System.out.println("This is before the update:");
        getContacts().forEach(System.out::println);
        // close session
        session.close();
    }

    @SuppressWarnings("unchecked")
    private static List<Contact> getContacts() {
        Session sessions = session.openSession();
        Criteria criteria = sessions.createCriteria(Contact.class);
        List<Contact> contacts = criteria.list();
        sessions.close();
        return contacts;
    }

    private static int save(Contact contact){
        Session sessions = session.openSession();
        sessions.beginTransaction();
        int id = (int)sessions.save(contact);
        sessions.getTransaction().commit();
        sessions.close();
        return id;
    }
}