Java: Hibernate: HelloWorld Sample Using Annotations and Programmatic Configuration

package helloworld;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;

@Entity
public class Message {
 @Id
 @GeneratedValue
 private Long id;
 private String text;

 public String getText() {
  return text;
 }

 public void setText(String text) {
  this.text = text;
 }
}

package helloworld;

import static org.junit.Assert.assertEquals;

import java.util.List;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.boot.Metadata;
import org.hibernate.boot.MetadataBuilder;
import org.hibernate.boot.MetadataSources;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.service.ServiceRegistry;
import org.junit.Test;

public class HelloWorldHibernate {
 @Test
 public void testHelloWorld() {
  
  /*
   * SessionFactory sessionFactory = new MetadataSources( new
   *   StandardServiceRegistryBuilder().configure("hibernate.cfg.xml").build())
   *   .buildMetadata().buildSessionFactory();
   */


  StandardServiceRegistryBuilder serviceRegistryBuilder = new StandardServiceRegistryBuilder();
  serviceRegistryBuilder
    //.applySetting("hibernate.connection.datasource", "books")
    .applySetting("hibernate.connection.url", "jdbc:mysql://localhost:3306/test")
    .applySetting("hibernate.connection.driver_class", "com.mysql.jdbc.Driver")
    .applySetting("hibernate.connection.user", "root")
    .applySetting("hibernate.connection.password", "****")
    .applySetting("hibernate.format_sql", "true")
    .applySetting("hibernate.use_sql_comments", "true")
    .applySetting("hibernate.hbm2ddl.auto", "create-drop");
  ServiceRegistry serviceRegistry = serviceRegistryBuilder.build();

  // The MetadataSources API has many methods for adding mapping sources;
  MetadataSources metadataSources = new MetadataSources(serviceRegistry);
  
  metadataSources.addAnnotatedClass(helloworld.Message.class);
  MetadataBuilder metadataBuilder = metadataSources.getMetadataBuilder();
  Metadata metadata = metadataBuilder.build();

  assertEquals(metadata.getEntityBindings().size(), 1);

  SessionFactory sessionFactory = metadata.buildSessionFactory();

  // Whenever you call getCurrentSession() in the same thread, you get the
  // same org.hibernate.Session
  Session session = sessionFactory.openSession();
  session.beginTransaction();

  Message message = new Message();
  message.setText("Hello World!");
  session.persist(message);
  session.getTransaction().commit();
  session.close();
  
  session = sessionFactory.openSession();
  session.beginTransaction();
  List<Message> messages = session.createCriteria(Message.class).list();
  // SELECT * from MESSAGE
  assertEquals(messages.size(), 1);
  assertEquals(messages.get(0).getText(), "Hello World!");
  session.getTransaction().commit();
  session.close();
 }
}