java - Inject a EntityManagerFactory through @PersitenceContext or @PersitenceUnit? -

i've thought @persistencecontext injecting entitymanager container-managed application, while @persistenceunit injecting entitymanagerfactory.

javadoc says

for persistenceunit (http://docs.oracle.com/javaee/7/api/javax/persistence/persistenceunit.html)

expresses dependency on entitymanagerfactory , associated persistence unit.

and persistencecontext (http://docs.oracle.com/javaee/7/api/javax/persistence/persistencecontext.html)

expresses dependency on container-managed entitymanager , associated persistence context.

so far good, reading jpa tutorial (see https://docs.oracle.com/cd/e19798-01/821-1841/bnbqy/index.html) contains example this

the following example shows how manage transactions in application uses application-managed entity manager:

@persistencecontext entitymanagerfactory emf; entitymanager em; @resource usertransaction utx; ... em = emf.createentitymanager(); try {   utx.begin();   em.persist(someentity);   em.merge(anotherentity);   em.remove(thirdentity);   utx.commit(); } catch (exception e) {   utx.rollback(); } 

so persistencecontext can refer entitymanagerfactory if we're talking application managed code?

disclaimer -- not related answers question guess -- persistenceunit vs persistencecontext

i've thought @persistencecontext injecting entitymanager container-managed application, while @persistenceunit injecting entitymanagerfactory.

that's true.

i guess example of jpa tutorial careless mistake. in same section 'application-managed entity managers' it's written

to obtain entitymanager instance, first must obtain entitymanagerfactory instance injecting application component means of javax.persistence.persistenceunit annotation:

@persistenceunit entitymanagerfactory emf;

then obtain entitymanager entitymanagerfactory instance:

entitymanager em = emf.createentitymanager();