在Jboss7 OSGI上休眠（无EJB）

Question

I use entity beans and some Stateless ejb that provide my HomeLocal and HomeRemote interface, where I inject persistenceContext and obtain EntityManager .

As new requirement (migration on Karaf) I have to get rid of all EJB.

My question is how can I replace this stateless ejb with simple DAO classes and inject or obtain Entity manager in these classes?

My JPA provider is hibernate.

I need some example, tutorials or any kind of help.

Answer 1

You could use the Apache Aries project:

Amusing you will be using blueprint, declare your bean and define a service (assuming you want to use services)

<blueprint xmlns="http://www.osgi.org/xmlns/blueprint/v1.0.0"
           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
           xmlns:jpa="http://aries.apache.org/xmlns/jpa/v1.0.0"
           xmlns:tx="http://aries.apache.org/xmlns/transactions/v1.0.0">

    <bean id="jpaDemo" init-method="init" class="org.demo.osgi.datasource.jpa.JpaComponentImpl">
        <jpa:context unitname="demo" property="entityManager"/>
        <tx:transaction method="*" value="Required"/>
    </bean>

    <service ref="jpaDemo" interface="org.demo.osgi.datasource.jpa.JpaComponent"/>

</blueprint>

The JpaComponent can then use the injected entityManager (code in Scala, but i'm sure you'll get the idea)

trait JpaComponent {

}
class JpaComponentImpl extends JpaComponent {

  val logger = org.slf4j.LoggerFactory.getLogger(classOf[JpaComponent])

  @BeanProperty
  var entityManager : EntityManager = _

  def init = {
    logger.info(s"em=${entityManager}")
  }
}

Place a persistence.xml in your bundle (eg, META-INF/persistence.xml ). Sample below:

<persistence-unit name="demo" transaction-type="JTA">
    <provider>org.hibernate.ejb.HibernatePersistence</provider>
    <jta-data-source>osgi:service/javax.sql.DataSource/(osgi.jndi.service.name=jdbc/jbtravel)</jta-data-source>
    <mapping-file>META-INF/airport.xml</mapping-file>
</persistence-unit>

You will need the following features:

• jpa
• hibernate
• jndi
• transaction

And the following bundles

• mvn:org.apache.aries/org.apache.aries.util/1.0.1
• mvn:org.apache.aries.jpa/org.apache.aries.jpa.api/1.0.1
• mvn:org.apache.aries.jpa/org.apache.aries.jpa.container.context/1.0.1

Plus set the following OSGI meta-data

• Meta-Persistence: META-INF/persistence.xml
• Service-Component: *

See also https://github.com/rparree/osgi-demos/tree/master/datasource for the sample from above