Spring Boot Annotations

Introduction

Annotations are how you talk to Spring. Knowing the top 25 covers 95% of day-to-day code. Here is the cheat-sheet you'll memorise within a week.

Understanding the topic

The essentials:

• @SpringBootApplication — main class entry point.
• @RestController, @Controller — HTTP endpoints.
• @RequestMapping, @GetMapping, @PostMapping… — route mapping.
• @PathVariable, @RequestParam, @RequestBody — request data.
• @Service, @Repository, @Component — bean stereotypes.
• @Autowired, @Qualifier, @Primary — wiring.
• @Configuration, @Bean — Java config.
• @Value, @ConfigurationProperties — config binding.
• @Transactional — transaction boundaries.
• @Valid, @NotBlank, @Email — input validation.
• @ControllerAdvice, @ExceptionHandler — global error handling.
• @Profile, @ConditionalOnProperty — env-aware beans.