How I can do to read the tag value for my persistence.xml <jta-data-source> in from a file config.properties

Question

I want to do something like this:

config.properties:

dsname=value;
anotherValue=anotherValue;

persitence.xml

<jta-data-source>${dsname}</jta-data-source>

Answer 1

The properties file is outside of my web project, I am using JPA with EclipseLink but I need to initialize the parameter jta-data-source from the external file value "dsname"

actually:

<persistence-unit name="Unit-ejbPU" transaction-type="JTA">
  <provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>
    <jta-data-source>datasource</jta-data-source>
      <class>Clase1</class>
      <class>Clase2</class>
      <class>Clase3</class>
  <properties/>
</persistence-unit>

idea to make:

<persistence-unit name="Unit-ejbPU" transaction-type="JTA">
  <provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>
    <jta-data-source>${dsname}</jta-data-source>
      <class>Clase1</class>
      <class>Clase2</class>
      <class>Clase3</class>
  <properties/>
</persistence-unit>