Configuration and Mapping Files

Configuration and Mapping are very familiar keywords we used to hear in the hibernate, every hibernate program must need these 2 xml files.

Configuration:

Configuration is the file loaded into an hibernate application when working with hibernate, this

configuration file contains three types of information.

1. Connection Properties

2. Hibernate Properties

3. Mapping file name(s)

We must create one configuration file for each database we are going to use, suppose if we want

to connect with two databases, like Oracle, MySql, then we must create two configuration files.

No. of databases we are using = that many number of configuration files

We can write this configuration in two ways…

1. XML

2. writing Properties file.

We don’t have annotations here, actually in hibernate 1, 2.x we defined this configuration file by

writing .properties file, but from 3.x xml came into picture.

So, finally

Mapping File : XML, annotations

Configuration File : XML, .properties (old style)

Take a look upon few needed properties of configuration file

connection.driver_class

JDBC driver class e.g. com.mysql.jdbc.Driver

connection.url 

JDBC URL e.g. jdbc:mysql://localhost:3306/mydb

connection.username

database user e.g. root

connection.password

database user password e.g. root

show_sql 

Write all SQL statements to console e.g. true | false

dialect

particular relational database dialect name

This property makes Hibernate generate the appropriate SQL

for the chosen database.

e.g. org.hibernate.dialect.MySQLDialect (this is for MYSQL)

hbm2ddl.auto 

Automatically validates or create or update schema

DDL to the database when the

SessionFactory is created.

e.g. validate | update | create | create-drop

hibernate.connection.pool_size

Limits the number of connections waiting in the Hibernate

database connection pool.

e.g. 5 | 6

hibernate.connection.autocommit

Allows autocommit mode to be used for the JDBC connection.

e.g. true | false