JAVA: how to load database url from web.xml?

Question

I'm using persistence API and want to load jdbc URL from web.xml. URL should be a context parameter of servlet. I can't find how to construct EntityManagerFactory not using persistence.xml. May be I should create PersistenceUnit in servlet and set some parameters? Can you give me some short example?

Thank you

Answer 1

you can use method createEntityManagerFactory(String persistenceUnitName, Map properties) of class javax.persistence.Persistence . and insert all your parameters in the map

Answer 2

I personally find it the cleanest way to define a datasource in the servlet container usng JNDI and refer to that from the persistence.xml.

This also solves one configuration issue when migrating from test-uat-prod as I can use the same datasource name on the machines.

Yeah, I know JNDI is not popular, but this works nice and it avoids having to manipulate hte web.xml which is also wrapped in the war.