How to externalize properties from JPAs persistence.xml?

Question

I would like to put some hibernate configuration in the properties file to make it editable without assembly and deployment.

I tried to solve my problem by following the Create JPA EntityManager instructions without the persistence.xml configuration file

app.properties:

hibernate.show_sql=true hibernate.dialect=org.hibernate.dialect.MySQLDialect hibernate.hbm2ddl.auto=validate hibernate.show_sql=true hibernate.format_sql=true hibernate.default_schema=myschema 

persistence.xml

 <?xml version="1.0" encoding="UTF-8"?> <!-- Persistence deployment descriptor for dev profile --> <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="pu"> <provider>org.hibernate.ejb.HibernatePersistence</provider> <jta-data-source>jdbc/appDatasource</jta-data-source> <properties> <property name="jboss.entity.manager.factory.jndi.name" value="java:/appEntityManagerFactory"/> </properties> </persistence-unit> </persistence> 

In the initialization code, the application executes the following sequence (which finds the properties),

 Properties props = new Properties(); InputStream is = ClassLoader.getSystemResourceAsStream( "app.properties" ); props.load( is ); Persistence.createEntityManagerFactory( "pu", props ); 

but with the error message does not appear:

  INFO [SessionFactoryImpl] building session factory INFO [SessionFactoryObjectFactory] Not binding factory to JNDI, no JNDI name configured ERROR [STDERR] javax.persistence.PersistenceException: [PersistenceUnit: pu] Unable to build EntityManagerFactory 

Can anyone understand what might be wrong in my configuration?

Versions: JBoss 4.3 Seam: 2.1.2

EDIT:

JBoss JNDI enters "pu" as the unit of continuity:

 persistence.units:ear=app.ear,jar=app.jar,unitName=pu (class: org.hibernate.impl.SessionFactoryImpl) 

Answer 1

As an alternative to your current approach, and since you use Hibernate, you can use Hibernate to configure JPA by declaring the hibernate.cfg.xml file using the hibernate.ejb.cfgfile property, for example:

 <persistence> <persistence-unit name="manager1" transaction-type="JTA"> <jta-data-source>java:/DefaultDS</jta-data-source> <properties> <property name="hibernate.ejb.cfgfile" value="/hibernate.cfg.xml"/> </properties> </persistence-unit> </persistence> 

I understand that hibernate.cfg.xml should only be in the classpath (so it can be outside the packed archive).

References

• Reference Guide for Hibernate Entity Manager
  • Table 2.1. Hibernate Entity Manager Properties

Answer 2

Just found a way for EclipseLink users. There is eclipselink.persistencexml ", the default value

 public static final String ECLIPSELINK_PERSISTENCE_XML_DEFAULT = "META-INF/persistence.xml"; 

but it cannot be redefined, although the documents say that it could be ...

 /** * The <code>"eclipselink.persistencexml"</code> property specifies the full * resource name to look for the persistence XML files in. If not specified * the default value defined by {@link #ECLIPSELINK_PERSISTENCE_XML_DEFAULT} * will be used. * <p> * IMPORTANT: For now this property is used for the canonical model * generator but it can later be used as a system property for customizing * weaving and application bootstrap usage. * <p> * This property is only used by EclipseLink when it is locating the * configuration file. When used within an EJB/Spring container in container * managed mode the locating and reading of this file is done by the * container and will not use this configuration. */ 

Answer 3

I used this mechanism, it seems to work for most properties, had problems with the non-jta-data source.

http://www.eclipse.org/eclipselink/api/2.4/index.html?org/eclipse/persistence/config/PersistenceUnitProperties.html

Answer 4

If you use Spring to manage and administer the object manager, then you can implement org.springframework.orm.jpa.persistenceunit.PersistenceUnitPostProcessor and pass external properties. I could successfully squeeze out all the properties from persistence.xml using this.