[Spring] Json 응답처리와 예외처리

공통된 포맷으로 Json 리턴하기

1. Json 포맷에 대한 Response class를 정의

@Getter
@AllArgsConstructor
public class Response<T> {
    private String resultCode;
    private String resultMessage;
    private T result;

    public static <T> Response<T> success(T result) {
        return new Response<T>("SUCCESS", null, result);
    }

    public static Response<Void> error(String resultCode, String resultMessage) {
        return new Response<Void>(resultCode, resultMessage, null);
    }

}

2. controller에서, 정의한 Response class를 사용하여 return

@RestController
@RequestMapping("/api/v1/users")
@RequiredArgsConstructor
public class UserController {

    private final UserService userService;

    @PostMapping("/join")
    public Response<UserJoinResponse> join(@RequestBody UserJoinRequest request) {
        return Response.success(UserJoinResponse.fromUser(userService.join(request.getName(), request.getPassword())));
    }

    @PostMapping("/login")
    public Response<UserLoginResponse> login(@RequestBody UserLoginRequest request) {
        String token = userService.login(request.getName(), request.getPassword());
        return Response.success(new UserLoginResponse(token));
    }

}

예외 처리

1. 에러코드를 Enum으로 정의

@Getter
@RequiredArgsConstructor
public enum ErrorCode {

    USER_NOT_FOUND(HttpStatus.NOT_FOUND, "User not founded"),
    INVALID_PASSWORD(HttpStatus.UNAUTHORIZED, "Invalid password"),
    DUPLICATED_USER_NAME(HttpStatus.CONFLICT, "Duplicated user name"),
    ;

    private final HttpStatus status;
    private final String message;
}

2.

@Getter
@AllArgsConstructor
public class SimpleSnsApplicationException extends RuntimeException {

    private ErrorCode errorCode;
    private String message;


    public SimpleSnsApplicationException(ErrorCode errorCode) {
        this.errorCode = errorCode;
        this.message = null;
    }

    @Override
    public String getMessage() {
        if (message == null) {
            return errorCode.getMessage();
        } else {
            return String.format("%s. %s", errorCode.getMessage(), message);
        }

    }
}

3. service에서 정의한 예외처리 활용

@Service
@RequiredArgsConstructor
public class UserService implements UserDetailsService {

    private final UserRepository userRepository;
    private final BCryptPasswordEncoder encoder;

    @Value("${jwt.secret-key}")
    private String secretKey;

    @Value("${jwt.token.expired-time-ms}")
    private Long expiredTimeMs;


    @Override
    public User loadUserByUsername(String userName) throws UsernameNotFoundException {
        return userRepository.findByUserName(userName).map(User::fromEntity).orElseThrow(
                () -> new SimpleSnsApplicationException(ErrorCode.USER_NOT_FOUND, String.format("userName is %s", userName))
        );
    }

    public String login(String userName, String password) {
        User savedUser = loadUserByUsername(userName);
        if (!encoder.matches(password, savedUser.getPassword())) {
            throw new SimpleSnsApplicationException(ErrorCode.INVALID_PASSWORD);
        }
        return JwtTokenUtils.generateAccessToken(userName, secretKey, expiredTimeMs);
    }


    public User join(String userName, String password) {
        // check the userId not exist
        userRepository.findByUserName(userName).ifPresent(it -> {
            throw new SimpleSnsApplicationException(ErrorCode.DUPLICATED_USER_NAME, String.format("userName is %s", userName));
        });

        UserEntity savedUser = userRepository.save(UserEntity.of(userName, encoder.encode(password)));
        return User.fromEntity(savedUser);
    }
}

4.

@RestControllerAdvice
public class GlobalControllerAdvice {

    @ExceptionHandler(SimpleSnsApplicationException.class)
    public ResponseEntity<?> errorHandler(SimpleSnsApplicationException e) {
        return ResponseEntity.status(e.getErrorCode().getStatus())
                .body(Response.error(e.getErrorCode().name(), e.getMessage()));
    }
}

@ControllerAdvice를 이용해 오류가 발생했을 때 처리할 로직을 한 곳에 모으고
@ExceptionHandler을 이용해 발생한 오류에 대한 세세한 처리

 

 

성공일 때, 응답값

{
    "resultCode": "SUCEESS",
    "result": {
        "id": 2,
        "userName": "test",
        "role": "USER"
        }    
}

실패일 때, 응답값

{
    "resultCode": "DUPLICATED_USER_NAME",
    "result": null
}

코드 구조