public class MyOwnDatasourceConnectionProvider implements ConnectionProvider
{

    private DataSource dataSource;

    public void configure(Properties arg0) throws HibernateException {
       
    }

    public Connection getConnection() throws SQLException {
        return this.getDataSource().getConnection();
    }

    public void closeConnection(Connection arg0) throws SQLException {
        if(this.getConnection() != null) this.getConnection().close();
    }

    public void close() throws HibernateException {
    }

    public boolean supportsAggressiveRelease() {
        return true;
    }

    public DataSource getDataSource()
    {
        if(this.dataSource == null)
        {
            this.dataSource = //... here your code that returns your own DataSource instance
        }
        return this.dataSource;
    }
}

import org.hibernate.*;
import org.hibernate.cfg.*;

public class HibernateUtil {

    private static final SessionFactory sessionFactory;
   

    static {
        try {           
            // Create the SessionFactory from hibernate.cfg.xml
            Configuration configuration = new Configuration().configure();

            // Define my own ConnectionProvider (watch out connection parameters from hibernate.cfg.xml will no longer be used)
            configuration.setProperty(Environment.CONNECTION_PROVIDER, MyOwnDatasourceConnectionProvider.class.getName());

            sessionFactory = configuration.buildSessionFactory();
        } catch (Throwable ex) {
            // Make sure you log the exception, as it might be swallowed
            System.err.println("Initial SessionFactory creation failed." + ex);
            throw new ExceptionInInitializerError(ex);
        }
    }

    public static SessionFactory getSessionFactory() {
        return sessionFactory;
    }
}