# Bean Validation (Spring Boot)

> Bean Validation, 어노테이션(@NotNull, @Size, @Email), @Valid, BindingResult, 커스텀 검증기

- 25 면접 질문
- Mid-Level
- [면접 질문: Spring Boot](https://sharpskill.dev/ko/technologies/spring-boot/interview-questions.md)

## 1. Spring에서 @Valid 어노테이션의 역할은 무엇인가요?

**답변**

@Valid는 어노테이션이 적용된 객체에 대해 Bean Validation 제약 조건(JSR 303/380)을 트리거합니다. 이 어노테이션은 jakarta.validation 패키지에서 제공되며 Spring이 이를 인식하여 컨트롤러의 DTO를 자동으로 검증합니다. 예외를 던지지 않고 오류를 가져오려면 @Valid를 BindingResult와 함께 사용하세요.

## 2. String에 대한 @NotNull과 @NotBlank의 주요 차이점은 무엇입니까?

**답변**

@NotNull은 값이 null이 아닌지만 확인하지만, @NotBlank는 String이 null도 아니고 비어 있지도 않으며 공백 문자로만 구성되지 않았는지 확인합니다. @NotBlank가 더 엄격하며 공백이 허용되지 않는 텍스트 필드에 적합합니다. username이나 email 같은 필수 필드에는 @NotBlank를 사용하세요.

## 3. @Size(min=3, max=50) 어노테이션은 무엇을 확인합니까?

**답변**

@Size는 크기(String의 경우 길이, 컬렉션의 경우 요소 수)가 min과 max 사이(양 끝 포함)에 있는지 검증합니다. 이 제약은 String, Collection, Map, Array에 적용됩니다. String 검증의 경우 @Size는 바이트 수가 아니라 문자 수를 확인합니다.

## 22개 추가 질문 이용 가능

- 이메일 주소를 검증하려면 어떤 어노테이션을 사용해야 합니까?
- 숫자가 0 이상인지 검증하려면 어떤 제약을 사용해야 합니까?

무료로 가입하기: https://sharpskill.dev/ko/login

## 기타 Spring Boot 면접 주제

- [Spring Core - IoC & DI](https://sharpskill.dev/ko/technologies/spring-boot/interview-questions/spring-core-ioc-di.md): 22개 질문, Junior
- [Spring Boot Auto-Configuration](https://sharpskill.dev/ko/technologies/spring-boot/interview-questions/spring-boot-auto-configuration.md): 20개 질문, Junior
- [Spring Boot Starters](https://sharpskill.dev/ko/technologies/spring-boot/interview-questions/spring-boot-starters.md): 18개 질문, Junior
- [Application Properties & YAML](https://sharpskill.dev/ko/technologies/spring-boot/interview-questions/application-properties-yml.md): 16개 질문, Junior
- [SLF4J 및 Logback을 사용한 로깅](https://sharpskill.dev/ko/technologies/spring-boot/interview-questions/logging.md): 20개 질문, Junior
- [Spring Boot DevTools](https://sharpskill.dev/ko/technologies/spring-boot/interview-questions/spring-boot-devtools.md): 15개 질문, Junior
- [Spring MVC Basics](https://sharpskill.dev/ko/technologies/spring-boot/interview-questions/spring-mvc-basics.md): 20개 질문, Mid-Level
- [Spring REST Controllers](https://sharpskill.dev/ko/technologies/spring-boot/interview-questions/spring-rest-controllers.md): 20개 질문, Mid-Level
- [Request & Response Handling](https://sharpskill.dev/ko/technologies/spring-boot/interview-questions/request-response-handling.md): 20개 질문, Mid-Level
- [예외 처리](https://sharpskill.dev/ko/technologies/spring-boot/interview-questions/exception-handling.md): 25개 질문, Mid-Level
- [Spring Data JPA 기초](https://sharpskill.dev/ko/technologies/spring-boot/interview-questions/spring-data-jpa-basics.md): 25개 질문, Mid-Level
- [JPA 엔티티 및 관계](https://sharpskill.dev/ko/technologies/spring-boot/interview-questions/jpa-entities-relationships.md): 30개 질문, Mid-Level
- [JPA 쿼리](https://sharpskill.dev/ko/technologies/spring-boot/interview-questions/jpa-queries.md): 30개 질문, Mid-Level
- [Spring Data Repositories](https://sharpskill.dev/ko/technologies/spring-boot/interview-questions/spring-data-repositories.md): 25개 질문, Mid-Level
- [Spring Security 기초](https://sharpskill.dev/ko/technologies/spring-boot/interview-questions/spring-security-basics.md): 25개 질문, Mid-Level
- [Spring Boot Actuator](https://sharpskill.dev/ko/technologies/spring-boot/interview-questions/spring-boot-actuator.md): 20개 질문, Mid-Level
- [JUnit과 Mockito를 사용한 단위 테스트](https://sharpskill.dev/ko/technologies/spring-boot/interview-questions/testing-junit-mockito.md): 30개 질문, Mid-Level
- [Spring Boot 테스트](https://sharpskill.dev/ko/technologies/spring-boot/interview-questions/spring-boot-testing.md): 30개 질문, Mid-Level
- [Profiles와 Environment](https://sharpskill.dev/ko/technologies/spring-boot/interview-questions/profiles-environment.md): 20개 질문, Mid-Level
- [RestTemplate 및 WebClient](https://sharpskill.dev/ko/technologies/spring-boot/interview-questions/resttemplate-webclient.md): 24개 질문, Mid-Level
- [Async와 스케줄링](https://sharpskill.dev/ko/technologies/spring-boot/interview-questions/async-scheduling.md): 25개 질문, Mid-Level
- [Spring을 사용한 캐싱](https://sharpskill.dev/ko/technologies/spring-boot/interview-questions/caching.md): 25개 질문, Mid-Level
- [Spring WebFlux (리액티브)](https://sharpskill.dev/ko/technologies/spring-boot/interview-questions/spring-webflux.md): 25개 질문, Mid-Level
- [Spring 트랜잭션](https://sharpskill.dev/ko/technologies/spring-boot/interview-questions/transactions.md): 30개 질문, Senior
- [고급 인증 및 인가](https://sharpskill.dev/ko/technologies/spring-boot/interview-questions/authentication-authorization.md): 30개 질문, Senior
- [JWT 및 스테이트리스 보안](https://sharpskill.dev/ko/technologies/spring-boot/interview-questions/jwt-stateless-security.md): 20개 질문, Senior
- [OAuth2와 Authorization Server](https://sharpskill.dev/ko/technologies/spring-boot/interview-questions/oauth2-authorization-server.md): 20개 질문, Senior
- [Spring Boot와 Docker](https://sharpskill.dev/ko/technologies/spring-boot/interview-questions/spring-boot-docker.md): 19개 질문, Senior
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- [성능 최적화](https://sharpskill.dev/ko/technologies/spring-boot/interview-questions/performance-optimization.md): 30개 질문, Senior
- [GraalVM Native Images](https://sharpskill.dev/ko/technologies/spring-boot/interview-questions/graalvm-native-images.md): 20개 질문, Senior

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