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

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>

Related Tags for Hibernate persistence.xml:

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