Question

If I create an EJB3 bean (say a stateless session bean) in an application using Spring 2.5 for DI, how should I inject dependencies from Spring into the bean without coupling the bean to Spring?

Answer 1

I don’t know if you consider applying an interceptor as coupling but that’s to my knowledge the standard approach. From the Chapter 18. Enterprise Java Beans (EJB) integration of the documentation:

18.3.2. EJB 3 injection interceptor

For EJB 3 Session Beans and
Message-Driven Beans, Spring provides
a convenient interceptor that resolves
Spring 2.5’s @Autowired annotation
in the EJB component class:
org.springframework.ejb.interceptor.SpringBeanAutowiringInterceptor.
This interceptor can be applied
through an
@Interceptors
annotation in the EJB component class,
or through an interceptor-binding XML
element in the EJB deployment
descriptor.

@Stateless
@Interceptors(SpringBeanAutowiringInterceptor.class)
public class MyFacadeEJB implements MyFacadeLocal {

    // automatically injected with a matching Spring bean
    @Autowired
    private MyComponent myComp;

    // for business method, delegate to POJO service impl.
    public String myFacadeMethod(...) {
        return myComp.myMethod(...);
    }
    ...
}

SpringBeanAutowiringInterceptor by
default obtains target beans from a
ContextSingletonBeanFactoryLocator,
with the context defined in a bean
definition file named
beanRefContext.xml. By default, a
single context definition is expected,
which is obtained by type rather than
by name. However, if you need to
choose between multiple context
definitions, a specific locator key is
required. The locator key (i.e. the
name of the context definition in
beanRefContext.xml) can be
explicitly specified either through
overriding the
getBeanFactoryLocatorKey method in a
custom
SpringBeanAutowiringInterceptor
subclass.

The only other option I’m aware of (extending the EJB 2.x support classes) is much worse from a coupling point of view (and thus doesn’t answer your question).

See also

• Default Injecting Spring bean to EJB3 SLSB without @Autowired Annotation