Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Welcome To Ask or Share your Answers For Others

Categories

0 votes
910 views
in Technique[技术] by (71.8m points)

jsf 2 - Injecting entity manager into managed bean

It is possible to inject entity manager (or its factory) into jsf managed bean using @PersistenceContext (or @PersistenceUnit)?

I Tried it but nothing, I obtain a NullPointerException.

See Question&Answers more detail:os

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome To Ask or Share your Answers For Others

1 Reply

0 votes
by (71.8m points)

Yes it is possible. This is the syntax.

@PersistenceContext
EntityManager em;

You need to have a persistence.xml in your project. Btw: I'm running Glassfish 3.

After this you can then use methods like em.createNamedQuery.

Also remember the injection takes place after the constructor so if your trying to do database functions in the constructor this will not work. You will have to add the @PostConstruct annotation to a method. This is probably the problem your having.


与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
OGeek|极客中国-欢迎来到极客的世界,一个免费开放的程序员编程交流平台!开放,进步,分享!让技术改变生活,让极客改变未来! Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Click Here to Ask a Question

...