This is the solution I've ended up going with. Instead of using SecurityContextHolder in my controller, I want to inject something which uses SecurityContextHolder under the hood but abstracts away that singleton-like class from my code. I've found no way to do this other than rolling my own interface, like so:
public interface SecurityContextFacade {
SecurityContext getContext();
void setContext(SecurityContext securityContext);
}
Now, my controller (or whatever POJO) would look like this:
public class FooController {
private final SecurityContextFacade securityContextFacade;
public FooController(SecurityContextFacade securityContextFacade) {
this.securityContextFacade = securityContextFacade;
}
public void doSomething(){
SecurityContext context = securityContextFacade.getContext();
// do something w/ context
}
}
And, because of the interface being a point of decoupling, unit testing is straightforward. In this example I use Mockito:
public class FooControllerTest {
private FooController controller;
private SecurityContextFacade mockSecurityContextFacade;
private SecurityContext mockSecurityContext;
@Before
public void setUp() throws Exception {
mockSecurityContextFacade = mock(SecurityContextFacade.class);
mockSecurityContext = mock(SecurityContext.class);
stub(mockSecurityContextFacade.getContext()).toReturn(mockSecurityContext);
controller = new FooController(mockSecurityContextFacade);
}
@Test
public void testDoSomething() {
controller.doSomething();
verify(mockSecurityContextFacade).getContext();
}
}
The default implementation of the interface looks like this:
public class SecurityContextHolderFacade implements SecurityContextFacade {
public SecurityContext getContext() {
return SecurityContextHolder.getContext();
}
public void setContext(SecurityContext securityContext) {
SecurityContextHolder.setContext(securityContext);
}
}
And, finally, the production Spring config looks like this:
<bean id="myController" class="com.foo.FooController">
...
<constructor-arg index="1">
<bean class="com.foo.SecurityContextHolderFacade">
</constructor-arg>
</bean>
It seems more than a little silly that Spring, a dependency injection container of all things, has not supplied a way to inject something similar. I understand SecurityContextHolder was inherited from acegi, but still. The thing is, they're so close - if only SecurityContextHolder had a getter to get the underlying SecurityContextHolderStrategy instance (which is an interface), you could inject that. In fact, I even opened a Jira issue to that effect.
One last thing - I've just substantially changed the answer I had here before. Check the history if you're curious but, as a coworker pointed out to me, my previous answer would not work in a multi-threaded environment. The underlying SecurityContextHolderStrategy used by SecurityContextHolder is, by default, an instance of ThreadLocalSecurityContextHolderStrategy, which stores SecurityContexts in a ThreadLocal. Therefore, it is not necessarily a good idea to inject the SecurityContext directly into a bean at initialization time - it may need to be retrieved from the ThreadLocal each time, in a multi-threaded environment, so the correct one is retrieved.