Spring Boot Annotations Overview

A handful of annotations account for most of what you'll write in a typical Spring Boot application.

@SpringBootApplication — marks the main class, enables auto-configuration & component scan
@RestController / @Controller — marks a class as a web request handler
@Service, @Repository, @Component — stereotypes for the IoC container
@Autowired — injects a dependency from the container
@RequestMapping / @GetMapping / @PostMapping — maps HTTP routes to methods
@Value — injects a value from application.properties

@RestController
@RequestMapping("/api/users")
public class UserController {

    @Autowired
    private UserService userService;

    @GetMapping("/{id}")
    public User getUser(@PathVariable Long id) {
        return userService.findById(id);
    }
}