Comprehensive Guide to Spring MVC and Spring Boot Annotations

Spring MVC provides request‑mapping annotations such as @RequestMapping, @GetMapping, @PostMapping, @PutMapping, @DeleteMapping, and @PatchMapping, which map HTTP requests to controller methods; they require @Controller or @RestController and support attributes like value, method, params, header, consumes, and produces.

Additional MVC annotations include @RequestBody for binding request bodies, @ResponseBody for writing method return values to the response, @ControllerAdvice with @ExceptionHandler, @ResponseStatus, @PathVariable, @RequestParam, @ModelAttribute, @CrossOrigin, and @InitBinder, each serving specific request‑handling purposes.

Spring Bean annotations cover component scanning ( @ComponentScan) and stereotype annotations ( @Component, @Service, @Repository). The @Bean annotation registers factory methods, with optional initMethod and destroyMethod. Bean scope is controlled by @Scope (e.g., singleton, prototype, request, session); an example:

@Scope(value = ConfigurableBeanFactory.SCOPE_PROTOTYPE)

Dependency‑injection annotations include @Autowired (usable on constructors, setters, or fields), @Qualifier for disambiguating multiple beans of the same type, @Primary to set a default bean, and lifecycle annotations @PostConstruct and @PreDestroy for initialization and cleanup.

Spring Boot simplifies application setup with @SpringBootApplication, which combines @Configuration, @EnableAutoConfiguration, and @ComponentScan. Conditional annotations such as @ConditionalOnClass, @ConditionalOnBean, @ConditionalOnMissingBean, @ConditionalOnProperty, @ConditionalOnResource, @ConditionalOnWebApplication, and @ConditionalExpression enable fine‑grained auto‑configuration based on classpath, bean presence, property values, resources, or custom SpEL expressions. Example main class:

@SpringBootApplication
public class Application {
    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }
}

The article concludes by summarizing the most commonly used Spring Boot annotations, emphasizing a unified understanding of annotation‑driven development, and notes that less‑frequent annotations will be covered in a future session.