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

Question

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

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.