beginner~2h
Core Annotations & Auto-Configuration
Four annotations do almost identical things mechanically, and picking the wrong one is a code-smell, not a bug. This module is why they're different, and how Boot decides what to wire up without you asking.
Learning objectives
- Beginner: Use @Service, @Repository, and @RestController by their intended role consistently across a small project, even though they're all mechanically @Component.
- Intermediate: Recognize when auto-configuration has silently provided a bean you didn't define, by checking what starters are on the classpath rather than assuming "it just works."
- Advanced: Deliberately override one piece of Boot's auto-configuration (e.g. a custom DataSource) and understand exactly why your bean takes precedence, via @ConditionalOnMissingBean's semantics.
This is a Pro chapter
Sign in, then upgrade to Pro or Power to unlock this and the full Spring Ecosystem Mastery library.
Core Annotations & Auto-Configuration