As Spring AOP creates proxies of target classes or objects to apply crosscutting concerns (Aspects), it needs to perform subclassing of the targeted class or object. As we already know, with subclassing, Spring AOP cannot apply crosscutting concerns on classes or methods that are final or static.

On the other hand, AspectJ weaves crosscutting concerns into the actual code using byte-code weaving and hence it doesn't need to subclass the targeted class or object.