Connection to Database Using Hibernate

A Java application can connect to a MySQL database through Hibernate ORM by creating the environment, adding a database node, configuring the Hibernate files, generating entity mappings, and executing database operations through a Hibernate session.

Create the Environment

Create the Database and Table

Create a database user with the values used in the source example:

Create a table named books inside jelasticDb with these fields:

• book_name
• book_author

Configure hibernate.cfg.xml

Add the database dialect, driver, connection URL, credentials, session context, and mapping resource:

<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>

The connection URL format is:

jdbc:mysql://mysql{node_id}.{your_env_name}.{hoster_domain}:3306/jelasticDb

Configure hibernate.revenge.xml

Define the database catalog and the table that Hibernate should process:

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

Generate Hibernate Mapping Files

Use Hibernate reverse engineering to generate these files in the web project:

• Books.java
• Books.hbm.xml

Create the standard HibernateUtil.java helper file as well. The source tutorial states that no changes are required in this utility file.

Execute a Database Operation

Create a Java method that opens the current Hibernate session, starts a transaction, saves a book record, and commits the transaction:

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();
}

Expected Result

The Hibernate configuration connects the Java application to jelasticDb, maps the books table to generated Java and XML mapping files, and inserts a new record through a Hibernate transaction.

Important Notes

• Replace every connection-string placeholder with the actual environment values.
• Use secure database credentials instead of the tutorial values.
• Ensure that the JDBC connector JAR is available to the application server.
• Keep the mapping resource path consistent with the generated Hibernate mapping file.
• Confirm that the database name and table name match the reverse-engineering configuration.
• Review application-server logs when Hibernate cannot create a session or connect to MySQL.

Common Issues and Solutions