A lot has changed in the Spring world since this question was answered. Spring has simplified getting the current user in a controller. For other beans, Spring has adopted the suggestions of the author and simplified the injection of 'SecurityContextHolder'. More details are in the comments.
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.
