My team of software developers at work was discussing a book when the question of singletons came up. The format of our discussions was to discuss one chapter in each meeting which everybody had read before. During the meeting we'd try to apply the lessons from the book to examples from our own code and projects. We'd also tried to agree on some coding and design standards to apply to our own team work. So far that's great!
One time, the discussion came to the use of Singletons, but it was a very short discussion, because someone said "we don't use Singletons because we do that with Spring". I insisted that in this case, we should discuss some ground rules and best practices for the use of Spring, but out of the entire team nobody was interested in that thought. I insisted one more time, but the crowd then simply went on with the meeting agenda.
At the time of that meeting (several months ago, but still vivid in my mind), I didn't know much about Spring and all its magic and had hoped I would get a quick lesson out of the meeting. Now, I still haven't managed to read a full book chapter or even blog article about Spring (their dryness makes me fall asleep), but I have seen a lot of the Spring code in our project. And while I have never seen good Spring code, the one in our project just seems wrong to me. Too many levels of abstraction mixed and all intertwined. Too much duplication in Spring contexts for tests and production. And that makes simple refactorings (even renamings) much harder.
This week, the topic came up again, because I talked about it with our development coach Steve Freeman, who shares my suspicion about Spring being misused more than it's actually well used. In a discussion I had with one of coworkers right after, my otherwise so intelligent and reasonable coworker insisted that using Spring is always good, because we use code that has been written by experts and is well-tested in many big systems for a long time. My point was, that we don't actually use much of Spring's functionality, but rather we just use Spring XML as another language to express what could be just as conveniently expressed in Java – even with the advantage of allowing better code-surfing (following references), better refactoring, and a better architecture overall.
In short, my impression is that by doing things "with Spring" we just hand over responsibility over our architecture to "the experts" and give up to think about it ourselves. We all agree that "Singletons are bad", but then again, what's a Spring context if not a big uniform sea of intertwined Singletons? My coworker says: "Spring has important functionality like figuring out the order of bean dependencies for you." But then I totally agree with Steve who says: "Doing the bean creation yourself gives you crucial feedback about the design of your code."
Using Spring dependency injection blindly means giving up you architecture. I am not going to do that, because I am a responsible architect.