如何调试Spring注释？

Question

I have been using annotations on my Spring Boot project, and they are black boxes to me. Unfortunately, I ran into an issue with the annotations and had no idea how to track down the issue. I was using the @PageableDefault annotation on my controller method with the @RepositoryRestController annotation at the class level, which resulted in my Pageable object to be null under Spring Boot 1.4.1. If I used @Controller , my pageable object would be populated correct. This ended up being a bug DATAREST-906 in Spring Data Rest and fixed in Spring Boot 1.4.2.

As a use case above what should I have done to debug this issue? Where should I have put my breakpoint to go down the rabbit hole?

Answer 1

You need to find the code that actually checks for the annotation and executes some logic based on it. This could theoretically happen in several places. If you search for occurrences of WhateverAnnotation.class in the source code you can find those places. You can also put breakpoints there, if you've linked the source properly in your IDE.