how to modify properties after create entity manager factory from persistence.xml

Question

i have a persistence.xml in META-INF/ folder:

<persistence-unit name="dev" transaction-type="RESOURCE_LOCAL">
<properties>
  <property name="javax.persistence.jdbc.url" value="jdbc:postgresql://localhost:5432/events" />
  <property name="javax.persistence.jdbc.user" value="postgres" />
  <property name="javax.persistence.jdbc.password" value="" />
  <property name="javax.persistence.jdbc.driver" value="org.postgresql.Driver" />
  <property name="hibernate.dialect" value="org.hibernate.dialect.PostgreSQLDialect" />
  <property name="hibernate.connection.provider_class" value="org.hibernate.connection.C3P0ConnectionProvider" />
  <property name="hibernate.show_sql" value="false" />
</properties>
</persistence-unit>

in java code i create entity manager facotry from that persistence.xml

_emf = Persistence.createEntityManagerFactory("dev");
_em = _emf.createEntityManager();

however i want do change only the jdbc url/user/password dynamically for test, my plan is to save those parameters in a config file and read them as needed, so is there a way i can update them after i create entitymanagerfactory from persistence.xml? so it would like this:

_emf = Persistence.createEntityManagerFactory("dev");
_emf.setProperties("url", "test_url");
    ... other setts here ...
_em = _emf.createEntityManager();

thanks

Answer 1

When you create the EntityManagerFactory, you can pass a set of properties that will override what is defined in persistence.xml, e.g.:

Properties props = new Properties();
props.setProperty("javax.persistence.jdbc.url", "test_url");
_emf = Persistence.createEntityManagerFactory("dev", props);

If you want to modify the connection properties after the EntityManagerFactory was created, you must recreate it by calling createEntityManagerFactory() again.