How do I obtain a new stateful session bean in a servlet thread?

Question

I'm experimenting with EJB3

I would like to inject a stateful session bean into a servlet, so that each user that hits the servlet would obtain a new bean.

Obviously, I can't let the bean be an instance variable for the servlet, as that will be shared. And apparantly injecting local variables isn't allowed.

I can use the new operator to create a bean, but that doesn't seem the right approach.

Is there a right way to do this? It seems like what I'm trying to do is fairly straightforward, after all, we would want each new customer to find an empty shopping cart.

Doerrer

Answer 1

You can't use new to get a new SFSB.

What you typically do is to lookup a new one using the InitialContext.

MyBean bean = (MyBean) new InitialContext().lookup( name );

You get then a reference to a specific SFSB that you can reuse across requests.

From this answer:

You should not typically inject SFSB, unless it is into another SFSB or into a Java EE client. You should use @EJB on the referencing class (e.g. your servlet) to declare the ejb-ref and then do a JNDI lookup in the code to obtain the instance. This instance could then be placed directly in your Http session.

For more information about SFSB, you might be interested in these other answers from me:

• Stateful EJBs in web application?
• Java: Tracking a user login session - Session EJBs vs HTTPSession
• Correct usage of Stateful Beans with Servlets

Hope it helps.

Musquash

What should the name be for a new SFSB? – Doerrer

You should be able to provide a name in the @Stateful( name="xxx" ) and use it for lookup. It's actually a bit more complicated, and there are various kinds of name (see beanName, name, and mappedName) and whether prefix java:comp/env/ must be used or not. I never remember the subtleties between all these. Give a try to the simplest case, and spawn maybe another question otherwise. – Musquash