I believe that the decorator pattern is one of the most powerful design patterns out there. It is the rule “composition > inheritance” at it’s best: it makes your classes easily testable, it allows to decompose huge classes into smaller ones, and it makes your code reusable and modular. In fact, Spring Framework relies heavily on this pattern. Unfortunately, I think that Spring doesn’t provide a really convenient way to configure decorators with it. This is the second part of how to customize dependency injection in Spring, and today we’re going to see how to make Spring’s DI respect decorators.

I work with Spring Framework a lot. I can’t even remember a single project I had at work where I didn’t use it. There is one part of Spring that I use especially often – it’s DI (Dependency Injection). And as often as I use it, I face a situation where it turns out to be not smart enough for me. This article is a result of me trying to customize dependency injection in Spring to make it smarter as well as trying to get a deeper understanding of how does it work. I hope you’ll find it useful as well!