Because Hibernate is designed to operate in many different environments, there
are a large number of configuration parameters. Fortunately, most have sensible
default values and Hibernate is distributed with an example
hibernate.properties file in etc/ that shows
the various options. Just put the example file in your classpath and customize it.
An instance of org.hibernate.cfg.Configuration represents an entire set of mappings
of an application's Java types to an SQL database. The org.hibernate.cfg.Configuration
is used to build an (immutable) org.hibernate.SessionFactory. The mappings
are compiled from various XML mapping files.
You may obtain a org.hibernate.cfg.Configuration instance by instantiating
it directly and specifying XML mapping documents. If the mapping files are in the classpath,
use addResource():
Configuration cfg = new Configuration()
.addResource("Item.hbm.xml")
.addResource("Bid.hbm.xml");An alternative (sometimes better) way is to specify the mapped class, and let Hibernate find the mapping document for you:
Configuration cfg = new Configuration()
.addClass(org.hibernate.auction.Item.class)
.addClass(org.hibernate.auction.Bid.class);
Then Hibernate will look for mapping files named /org/hibernate/auction/Item.hbm.xml
and /org/hibernate/auction/Bid.hbm.xml in the classpath. This approach eliminates any
hardcoded filenames.
A org.hibernate.cfg.Configuration also allows you to specify configuration
properties:
Configuration cfg = new Configuration()
.addClass(org.hibernate.auction.Item.class)
.addClass(org.hibernate.auction.Bid.class)
.setProperty("hibernate.dialect", "org.hibernate.dialect.MySQLInnoDBDialect")
.setProperty("hibernate.connection.datasource", "java:comp/env/jdbc/test")
.setProperty("hibernate.order_updates", "true");This is not the only way to pass configuration properties to Hibernate. The various options include:
Pass an instance of java.util.Properties to
Configuration.setProperties().
Place a file named hibernate.properties in a root directory of the classpath.
Set System properties using java -Dproperty=value.
Include <property> elements in
hibernate.cfg.xml (discussed later).
hibernate.properties is the easiest approach if you want to get started quickly.
The org.hibernate.cfg.Configuration is intended as a startup-time object,
to be discarded once a SessionFactory is created.