Hibernate persistence.xml

Hibernate persistence.xml

In this section, you will learn how to configure persistence.xml and what is its need.

NEED

With in an application server or in a standalone application , entity managers configuration  resides in a persistence archive. Now , question arise - what is persistence archive?. Its a JAR file placed inside META-INF folder which must have a persistence.xml file. All the correctly annotated class( which contains @Entity annotation), all annotated packages and all Hibernate hbm.xml files included in the archive will be added to the persistence unit configuration.

How to configure ?

A smallest persistence.xml file is given below :

<persistence xmlns="http://java.sun.com/xml/ns/persistence"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd"
version="2.0">
<persistence-unit name="sample">
<jta-data-source>java:/DefaultDS</jta-data-source>
<properties>
<property name="hibernate.dialect" value="org.hibernate.dialect.HSQLDialect"/>
<property name="hibernate.hbm2ddl.auto" value="create-drop"/>
</properties>
</persistence-unit>
</persistence>

More elaborated persistence.xml  file is given below :

<persistence xmlns="http://java.sun.com/xml/ns/persistence"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd"
version="2.0">
<persistence-unit name="punit" transaction-type="JTA">
<provider>org.hibernate.ejb.HibernatePersistence</provider>
<jta-data-source>java:/DefaultDS</jta-data-source>
<mapping-file>ejbmap.xml</mapping-file>
<jar-file>App.jar</jar-file>
<class>net.roseindia.Student</class>
<class>net.roseindia.Teacher</class>
<class>net.roseindia.Department</class>
<shared-cache-mode>ENABLE_SELECTOVE</shared-cache-mode>
<validation-mode>CALLBACK</validation-mode>
<properties>
<property name="hibernate.dialect" value="org.hibernate.dialect.HSQLDialect"/>
<property name="hibernate.hbm2ddl.auto" value="create-drop"/>
</properties>
</persistence-unit>
</persistence>

Different type of persistence.xml configuration on different platform is given below :

MySQL with JDBC

<persistence
xmlns="http://java.sun.com/xml/ns/persistence"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/persistence
http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd"
version="1.0">

<persistence-unit name="punit">
<properties>
<property name="hibernate.ejb.cfgfile" value="/hibernate.cfg.xml"/>
<property name="hibernate.hbm2ddl.auto" value="create"/>
<property name="hibernate.archive.autodetection" value="class, hbm"/>
<property name="hibernate.show_sql" value="true"/>
<property name="hibernate.connection.driver_class" value="com.mysql.jdbc.Driver"/>
<property name="hibernate.connection.password" value="<password>"/>
<property name="hibernate.connection.url" value="jdbc:mysql://<host_name>:<port_number>/<database_name>"/>
<property name="hibernate.connection.username" value="<username>"/>
<property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect"/>
<property name="hibernate.c3p0.min_size" value="5"/>
<property name="hibernate.c3p0.max_size" value="20"/>
<property name="hibernate.c3p0.timeout" value="300"/>
<property name="hibernate.c3p0.max_statements" value="50"/>
<property name="hibernate.c3p0.idle_test_period" value="3000"/>
</properties>
</persistence-unit>
</persistence>

With OpenEJB transaction manager

<persistence version="1.0"
xmlns="http://java.sun.com/xml/ns/persistence"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/persistence 
http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd">

<persistence-unit name="myapp">
<provider>org.hibernate.ejb.HibernatePersistence</provider>
<jta-data-source>java:/jtaDS</jta-data-source>
<non-jta-data-source>java:/nonjtaDS</non-jta-data-source>

<properties>
<property name="hibernate.hbm2ddl.auto" value="create-drop"/>
<property name="hibernate.transaction.manager_lookup_class"
value="org.apache.openejb.hibernate.TransactionManagerLookup"/>
</properties>
</persistence-unit>
</persistence>

JBoss example with hsql

<persistence>
<persistence-unit name="myapp">
<provider>org.hibernate.ejb.HibernatePersistence</provider>
<jta-data-source>java:/DefaultDS</jta-data-source>
<properties>
<property name="hibernate.dialect" 
value="org.hibernate.dialect.HSQLDialect"/>
<property name="hibernate.hbm2ddl.auto" value="create-drop"/>
</properties>
</persistence-unit>
</persistence>

With EclipseLink

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="1.0"
xmlns="http://java.sun.com/xml/ns/persistence"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/persistence 
http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd">
<persistence-unit name="comics">
<class>eclipselinkrcp.Publisher</class>
<properties>
<property name="eclipselink.jdbc.driver" value="org.apache.derby.jdbc.ClientDriver"/>
<property name="eclipselink.jdbc.url" value="jdbc:derby://localhost:1527/appdb;create=true"/>
<property name="eclipselink.jdbc.user" value="app"/>
<property name="eclipselink.jdbc.password" value="app"/>

<property name="eclipselink.jdbc.read-connections.min" value="1" />
<property name="eclipselink.jdbc.write-connections.min" value="1" />
<property name="eclipselink.jdbc.batch-writing" value="JDBC" />

<!-- Logging -->
<property name="eclipselink.logging.level" value="FINE" />
<property name="eclipselink.logging.timestamp" value="false" />
<property name="eclipselink.logging.session" value="false" />
<property name="eclipselink.logging.thread" value="false" />
</properties>

</persistence-unit>
</persistence>