The persistence.xml
file is the deployment descriptor file for persistence using JPA. It specifies the persistence units and declares the managed persistence classes, the object/relation mapping, and the database connection details.
To configure the persistence.xml
file, the following tasks:
Example 17-2 illustrates a persistence.xml
file for a Java SE platform configuration (that is, outside a container).
Example 17-2 A persistence.xml File Specifying the Java SE Platform Configuration
<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 persistence_1_0.xsd" version="1.0"> <persistence-unit name="my-app" transaction-type="RESOURCE_LOCAL"> <provider>org.eclipse.persistence.jpa.PersistenceProvider</provider> <exclude-unlisted-classes>false</exclude-unlisted-classes> <properties> <property name="javax.persistence.jdbc.driver" value="oracle.jdbc.OracleDriver"/> <property name="javax.persistence.jdbc.url" value="jdbc:oracle:thin:@localhost:1521:orcl"/> <property name="javax.persistence.jdbc.user" value="scott"/> <property name="javax.persistence.jdbc.password" value="tiger"/> </properties> </persistence-unit> </persistence>
An EntityManagerFactory
provides an efficient way to construct EntityManager
instances for a database. You can instantiate the EntityManagerFactory
for the application (illustrated in Example 17-2) by using:
Persistence.createEntityManagerFactory("my-app");