Any JDO-enabled application will require (at least) one PersistenceManagerFactory. Typically applications create one per datastore being utilised. A PersistenceManagerFactory provides access to PersistenceManager_s which allow objects to be persisted, and retrieved. The _PersistenceManagerFactory can be configured to provide particular behaviour.

A simple way of creating a PersistenceManagerFactory is using a set of properties controlling its behaviour, as follows

Properties properties = new Properties();
properties.setProperty("javax.jdo.PersistenceManagerFactoryClass", "{my_implementation_pmf_class}");
properties.setProperty("javax.jdo.option.ConnectionURL", "jdbc:mysql://localhost/myDB");
properties.setProperty("javax.jdo.option.ConnectionUserName", "login");
properties.setProperty("javax.jdo.option.ConnectionPassword", "password");
PersistenceManagerFactory pmf = JDOHelper.getPersistenceManagerFactory(properties);

A slight variation on this, is to use a file containg these properties (jdo.properties for example) to create the PMF, like this

javax.jdo.PersistenceManagerFactoryClass={my_implementation_pmf_class} javax.jdo.option.ConnectionURL=jdbc:mysql://localhost/myDB javax.jdo.option.ConnectionUserName=login javax.jdo.option.ConnectionPassword=password

and then to create the PersistenceManagerFactory using this file

PersistenceManagerFactory pmf = JDOHelper.getPersistenceManagerFactory("jdo.properties");

You could alternatively make use of a JPA persistence.xml file to create a PMF, like this

<?xml version="1.0" encoding="UTF-8" ?>
<persistence xmlns="https://jakarta.ee/xml/ns/persistence"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="https://jakarta.ee/xml/ns/persistence
        https://jakarta.ee/xml/ns/persistence/persistence_3_0.xsd" version="3.0">
    <!-- MyApp persistence unit -->
    <persistence-unit name="MyApp">
        <class>mydomain.Product</class>
        <class>mydomain.Book</class>
        <class>mydomain.CompactDisc</class>
        <exclude-unlisted-classes/>
        <properties>
            <property name="datanucleus.ConnectionURL" value="jdbc:mysql://localhost/myDB"/>
            <property name="datanucleus.ConnectionUserName" value="mysql"/>
            <property name="datanucleus.ConnectionPassword" value=""/>
        </properties>
    </persistence-unit>
</persistence>

and then instantiate the PMF using the persistence unit name, defining the classes that have JDO annotations that make up this application.

PersistenceManagerFactory pmf = JDOHelper.getPersistenceManagerFactory("MyApp");

An alternative using JNDI would be to call JDOHelper.getPersistenceManagerFactory(jndiLocation, context);, hence accessing the properties via JNDI.

Whichever way we wish to obtain the PersistenceManagerFactory we have defined a series of properties to give the behaviour of the PersistenceManagerFactory. The first property specifies to use PMF of the implementation required to be used, and the following 4 properties define the datastore that it should connect to.

Standard JDO Properties