Question

I’m very new to Hibernate and just wanted to query the initial basics.

I’ve created my Hibernate bean as such…

package com.behaviour.chapter1;

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

@Entity
public class User {

    private int userId;
    private String firstName;

    @Id
    public int getUserId() {
        return userId;
    }
    public void setUserId(int userId) {
        this.userId = userId;
    }
    public String getFirstName() {
        return firstName;
    }
    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }
}

I’ve configured my hibernate.cfg.xml and db connection there. My question is simply, how do I actually call this from a main method and use it in Hibernate3.6.6? I was following a tutorial online but it was for Hibernate3.2 and it seems to be a bit different. If anyone could show me just a really simple main method calling this bean, creating a new user (that would create a user in this table) it would be greatly appreciated. Also – if anyone has any good Hibernate tutorial links that would be great 🙂

Thanks,

Answer 1

There are several ways of doing this, it is a matter of design choice, a basic way to achieve this will be to create the session factory from hibernate.cfg.xml file. Make sure the file can be located at your classpath.

And using the class below, create a Session Factory object which is then used to open up new Session’s

  public class HibernateUtil 
  {
    private static final SessionFactory sessionFactory;

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

Now to create a new user, do:

public class DaoFactory
{
   public void create(Object obj)throws Exception
   {
     Session session = HibernateUtil.getSessionFactory().getCurrentSession();
     session.beginTransaction();
     session.save(obj);
     session.getTransaction().commit();
   }
}

Main

public static void main(String[] args)
{
  try
  {
   User user = new User();
   user.setFirstName("david99world");
   DaoFactory factory = new DaoFactory();
   factory.create(user);
  }
   catch(Exception ex)
  {
   ex.printStackTrace(System.out);
  }
}

EDIT

Your hibernate.cfg.xml should look something like this:

<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<!-- Database connection settings -->
<property name="connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="connection.url">jdbc:mysql://localhost:3306/test</property>
<property name="connection.username">root</property>
<property name="connection.password">root</property>

<!-- JDBC connection pool (use the built-in) -->
<property name="connection.pool_size">1</property>

<!-- SQL dialect -->
<property name="dialect">org.hibernate.dialect.MySQLDialect</property>

<!-- Enable Hibernate's automatic session context management -->
<property name="current_session_context_class">thread</property>

<!-- Disable the second-level cache -->
<property name="cache.provider_class">org.hibernate.cache.NoCacheProvider</property>

<!-- Echo all executed SQL to stdout -->
<property name="show_sql">true</property>

<!-- Drop and re-create the database schema on startup -->
<property name="hbm2ddl.auto">none</property>

<mapping class="com.behaviour.chapter1.User"/>

</session-factory>
</hibernate-configuration>