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.

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.