How to debug/debug annotations in Java?

Question

Java

Annotated code is found in many libraries (for example, in Spring). But I don't understand how to debug it?
After all, you can put a breakpoint in a method or even a class field and go through the calls. It is clear what goes where.
And cases with annotations so far are a dark forest for me. You can’t put a breakpoint there, so I can’t understand step by step how they work. Therefore, an unexplored piece of the application remains. How to be? How to debug such code?

Answer 1

Is it me or do you really not understand what annotations are? An annotation by itself does nothing. It only marks classes/methods/fields/parameters. These annotations are processed by spring. It understands that if a class is marked with the @Controller annotation, then it is a controller and it will look for request handler methods in this class, which, for example, are marked with the @RequestMapping annotation.