Database Connection Via Hibernate

To connect to DB using Hibernate users have to make the next steps:

• Create an environment at the platform
• Add a database node to this environment
• Modify some configuration files in a web-app
• Execute queries

Let’s do it step by step:

1. Create environment with a database server (MySQL in our case):

2. Create a new user in a database: How to create a new user - click here.

Database name : jelasticDb
Username : jelastic
Password : jelastic

For this example we’ve created table books with fields book_name and book_author inside the jelasticDb database.

3. Modify the following configuration files of your web-application: hibernate.cfg.xml

<hibernate-configuration>
  <session-factory>
    <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
    <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
    <property name="hibernate.connection.url">jdbc:mysql://mysql{node_id}.{your_env_name}.{hoster_domain}:3306/jelasticDb</property>
    <property name="hibernate.connection.username">jelastic</property>
    <property name="hibernate.connection.password">jelastic</property>
    <property name="hibernate.current_session_context_class">thread</property>
    <mapping resource="com/Testdata.hbm.xml"/>
  </session-factory>
</hibernate-configuration>

Note

Don’t miss to put the correct values to the hibernate.connection.url string instead of the text inside curly brackets.

{obj.data1}

where {node_id} - ID of the container with MySQL server you want to receive the access to. It can be seen at the dashboard:

hibernate.revenge.xml

<hibernate-reverse-engineering>
  <schema-selection match-catalog="jelasticDb"/>
  <table-filter match-name="books"/>
</hibernate-reverse-engineering>

For the next step we’ve used reverse engineering mechanism and got 2 files in our web-project:

• Books.java
• Books.hbm.xml

Also you need to create the HibernateUtil.java file but do not need to change it.

4. Create a simple Java method, which will add a new row to the books table in our database:

public void addBook(){
        Session s = HibernateUtil.getSessionFactory().getCurrentSession();
        s.beginTransaction();
            Books book = new Books("romeo and juliet","william shakespeare ");
            s.save(book);
        s.getTransaction().commit();
}

that you have to put the connector for database (.jar library) to your project or to the appropriate web-server’s folder in the environment.