如何检查用户是否在控制器内登录Symfony2？

use JMS\SecurityExtraBundle\Annotation\Secure;
use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\HttpKernel\Exception\HttpException;
use Symfony\Component\Security\Core\Exception\AuthenticationException;
use Symfony\Component\Security\Core\Exception\BadCredentialsException;

class MyController extends Controller
{
    /**
     * @Secure(roles="IS_AUTHENTICATED_FULLY")
     */
    public function indexAction()
    {
        $session = $this->getRequest()->getSession();

        if ($session->has('username')) {
            return new Response('Welcome back!');
        }

        return new Response('Please log in.');
    }
}

private $encoder;

public function __construct(UserPasswordEncoderInterface $encoder)

{

    $this->encoder = $encoder;

}

public function authenticate(AuthRequest $request)

{

    $username = $request->getUsername();

    $password = $request->getPassword();

    if ($this->encoder->isPasswordValid($username, $password)) {

        $user = $this->getUser($username);

        $token = new TokenResponse($this->encoder->encodePassword($user, $password), $user->getRoles());

        $session = $request->getSession();

        $session->set('token', $token);

        return new AuthResponse($token);

    }

    throw new HttpException(401);

}

public function getCredentials(Request $request)

{

    $session = $request->getSession();

    $token = $session->get('token');

    if ($token) {

        return ['username' => $token->getUsername(), 'password' => $token->getPassword()];

    }

    return [];

}

public function getUser($username)

{

    $repository = $this->getContainer()->get('doctrine')->getRepository('MyAppUserBundle:User');

    $