Configuring hibernate programmatically

In the preceding section, we understood XML and the properties-based configuration. Hibernate also supports the programmatic configuration. To configure hibernate using this method, we have to work on a Java code and create an instance of the org.hibernate.cfg.Configuration class. There are multiple ways to configure hibernate.

How to do it…

First, write the following code:

Configuration configuration = new Configuration();

This will create an instance of the Configuration class using hibernate.cfg.xml or hibernate.properties, whichever is found in the classpath.

Provide the following mapping files to the configuration:

configuration = configuration.addResource("Employee.hbm.xml");
configuration = configuration.addResource("Department.hbm.xml");

You can use an alternate way, as shown in the following code:

Configuration configuration = new Configuration().addResource("Employee.hbm.xml").addResource("Department.hbm.xml");

We can also provide a direct mapping using the class, as shown in the following code:

configuration = configuration.addClass("Department.class");

This will also look for Department.hbm.xml.

We can also set a custom property. To set up the custom property, use the following method:

configuration.setProperty(propertyName, value);

For example, consider the following code:

configuration.setProperty("show_sql", true);

To set up multiple properties using the properties object, execute the following code:

configuration.setProperties(java.util.Properties properties);

Here is an example:

Properties properties = new Properties();
properties.put("hibernate.dialect", "org.hibernate.dialect.MySQLDialect");
properties.put("hibernate.connection.driver_class", "com.mysql.jdbc.Driver");
properties.put("hibernate.connection.url", "jdbc:mysql://localhost:3306/kode12");
properties.put("hibernate.connection.username", "root");
properties.put("hibernate.connection.password", "root");
properties.put("show_sql", "true");
properties.put("hbm2ddl.auto", "update");
configuration.setProperties(properties);

To read the mapping from the URL, you can use the following code:

configuration = configuration.addURL(java.net.URL url);

To read the mapping from the XML file, you can use the following code:

configuration = configuration.addXML(String xml);

How it works…

When we select the programmatic configuration option, the Configuration class is very important. Using the instance of the Configuration class, we will build a SessionFactory object, as shown in the following code:

SessionFactory sessionFactory = new Configuration().buildSessionFactory();

When the preceding code is executed, it creates a SessionFactory object using a .properties or .cfg file or whichever source is provided to create the configuration.