What methods are you wanting to test? What you are suggesting sounds more like an integration test than a unit test. If you are wanting to test the security mechisms or your configuration of them via the spring config files, you might want to use a browser based test tool like CubicTest/Selenium. This would allow you to test loging in with proper user, invalid user, etc.
Without more information, it's hard to make a better recommendation.
I’ve looked at a lot of different solutions, and in my humble opinion Aspose is the way to go. Here’s the link: http://aspose.com