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.
3.1. Programmatic configuration
An instance of org.hibernate.cfg.Configuration
represents an entire set of mappings of an application's Java types to an SQL database. The Configuration
is used to build an (immutable) SessionFactory
. The mappings are compiled from various XML mapping files.
You may obtain a 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 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 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 Configuration
is intended as a startup-time object, to be discarded once a SessionFactory
is created.