RestControllerAdvice (Exception 공통화)

1. 💡 Throw Exception

1.1. 예외의 구분

• 어플리케이션의 발생예외는 크게 체크예외, 언체크예외로 구분
• 체크예외 : 발생한 예외를 잡고(catch) 체크 후, 예외 복구&회피 등 구체적인 처리 필요
  • ex: ClassNotFoundException
• 언체크예외 : 예외를 잡고(catch) 따로 처리가 필요하지 않음
  • ex: NullPointerException, ArrayIndexOutOfBoundsException
• 휴먼에러로 인해 발생하는 오류는 전부 RuntimeException을 상속한 예외들임
• 자바는 많은 RuntimeException을 지원하지만 직접 예외를 만들어야 하는 경우도 있음

 

1.2. 의도적으로 예외 throw & catch 하기

• Custom Exception(enum) 생성
• 특정 계층에서 사용할 클래스 생성 후 생성자에 CustomException을 파라미터로 사용
• ExceptionAdvice에 @ExceptionHandler를 사용하는 메소드 추가 작성
• 예외가 발생할만한 서비스에 throw new Custom_Exception(Custom_enum.Method) 작성하여 throw해주기
• 던진 예외를 예외처리를 담당하는 클래스에 던진 예외를 잡기위한 @ExceptionHandler 메소드 생성

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2. 💡 구현

 

GlobalExceptionAdvice - 처리된 에러를 응답으로 전달
BusinessLogicException - 적절한 Custom 상태코드 반환
ExceptionCode (Enum) - Custom Status
ErrorResponse - 직접적인 에러 처리 클래스, 용도벌 of 메소드 사용으로 특정 Exception별 에러 처리

 

      

      

      

    
    

      <java />
    
@Slf4j
@RestControllerAdvice
public class GlobalExceptionAdvice {

    @ExceptionHandler
    @ResponseStatus(HttpStatus.BAD_REQUEST)
    public ErrorResponse handleMethodArgumentNotValidException(
            MethodArgumentNotValidException e) {
        final ErrorResponse response = ErrorResponse.of(e.getBindingResult());

        return response;
    }

    @ExceptionHandler
    @ResponseStatus(HttpStatus.BAD_REQUEST)
    public ErrorResponse handleConstraintViolationException(
            ConstraintViolationException e) {
        final ErrorResponse response = ErrorResponse.of(e.getConstraintViolations());

        return response;
    }

    @ExceptionHandler
    public ResponseEntity handleBusinessLogicException(BusinessLogicException e) {
        final ErrorResponse response = ErrorResponse.of(e.getExceptionCode());

        return new ResponseEntity<>(response, HttpStatus.valueOf(e.getExceptionCode()
                .getStatus()));
    }

    @ExceptionHandler
    @ResponseStatus(HttpStatus.METHOD_NOT_ALLOWED)
    public ErrorResponse handleHttpRequestMethodNotSupportedException(
            HttpRequestMethodNotSupportedException e) {

        final ErrorResponse response = ErrorResponse.of(HttpStatus.METHOD_NOT_ALLOWED);

        return response;
    }

    @ExceptionHandler
    @ResponseStatus(HttpStatus.BAD_REQUEST)
    public ErrorResponse handleHttpMessageNotReadableException(
            HttpMessageNotReadableException e) {

        final ErrorResponse response = ErrorResponse.of(HttpStatus.BAD_REQUEST,
                "Required request body is missing");

        return response;
    }

    @ExceptionHandler
    @ResponseStatus(HttpStatus.BAD_REQUEST)
    public ErrorResponse handleMissingServletRequestParameterException(
            MissingServletRequestParameterException e) {

        final ErrorResponse response = ErrorResponse.of(HttpStatus.BAD_REQUEST,
                e.getMessage());

        return response;
    }

    @ExceptionHandler
    @ResponseStatus(HttpStatus.INTERNAL_SERVER_ERROR)
    public ErrorResponse handleException(Exception e) {
        log.error("# handle Exception", e);
        /* 
         * TODO 애플리케이션의 에러는 에러 로그를 로그에 기록하고, 관리자에게 이메일이나 카카오 톡,
         * 슬랙 등으로 알려주는 로직이 있는게 좋음.
         */

        final ErrorResponse response = ErrorResponse.of(HttpStatus.INTERNAL_SERVER_ERROR);

        return response;
    }
}

 

 

      

      

      

    
    

      <java />
    
public class BusinessLogicException extends RuntimeException {

    @Getter
    private ExceptionCode exceptionCode;

    public BusinessLogicException(ExceptionCode exceptionCode) {
        super(exceptionCode.getMessage());
        this.exceptionCode = exceptionCode;
    }
}

 

 

      

      

      

    
    

      <java />
    
public enum ExceptionCode {

    MEMBER_NOT_FOUND(404, "Member not found"),
    MEMBER_EXISTS(409, "Member exists"),
    COFFEE_NOT_FOUND(404, "Coffee not found"),
    COFFEE_CODE_EXISTS(409, "Coffee Code exists"),
    ORDER_NOT_FOUND(404, "Order not found"),
    CANNOT_CHANGE_ORDER(403, "Order can not change"),
    NOT_IMPLEMENTATION(501, "Not Implementation"),
    INVALID_MEMBER_STATUS(400, "Invalid member status");

    @Getter
    private int status;

    @Getter
    private String message;

    ExceptionCode(int status, String message) {
        this.status = status;
        this.message = message;
    }
}

 

 

      

      

      

    
    

      <java />
    
@Getter
public class ErrorResponse {
    private int status;
    private String message;
    private List<FieldError> fieldErrors;
    private List<ConstraintViolationError> violationErrors;

    private ErrorResponse(int status, String message) {
        this.status = status;
        this.message = message;
    }

    private ErrorResponse(final List<FieldError> fieldErrors,
                          final List<ConstraintViolationError> violationErrors) {
        this.fieldErrors = fieldErrors;
        this.violationErrors = violationErrors;
    }

    public static ErrorResponse of(BindingResult bindingResult) {
        return new ErrorResponse(FieldError.of(bindingResult), null);
    }

    public static ErrorResponse of(Set<ConstraintViolation<?>> violations) {
        return new ErrorResponse(null, ConstraintViolationError.of(violations));
    }

    public static ErrorResponse of(ExceptionCode exceptionCode) {
        return new ErrorResponse(exceptionCode.getStatus(), exceptionCode.getMessage());
    }

    public static ErrorResponse of(HttpStatus httpStatus) {
        return new ErrorResponse(httpStatus.value(), httpStatus.getReasonPhrase());
    }

    public static ErrorResponse of(HttpStatus httpStatus, String message) {
        return new ErrorResponse(httpStatus.value(), message);
    }

    @Getter
    public static class FieldError {
        private String field;
        private Object rejectedValue;
        private String reason;

        private FieldError(String field, Object rejectedValue, String reason) {
            this.field = field;
            this.rejectedValue = rejectedValue;
            this.reason = reason;
        }

        public static List<FieldError> of(BindingResult bindingResult) {
            final List<org.springframework.validation.FieldError> fieldErrors = bindingResult.getFieldErrors();

            return fieldErrors.stream()
                    .map(error -> new FieldError(
                            error.getField(),
                            error.getRejectedValue() == null ? "" : error.getRejectedValue().toString(),
                            error.getDefaultMessage()))
                    .collect(Collectors.toList());
        }
    }

    @Getter
    public static class ConstraintViolationError {
        private String propertyPath;
        private Object rejectedValue;
        private String reason;

        private ConstraintViolationError(String propertyPath, Object rejectedValue, String reason) {
            this.propertyPath = propertyPath;
            this.rejectedValue = rejectedValue;
            this.reason = reason;
        }

        public static List<ConstraintViolationError> of(Set<ConstraintViolation<?>> constraintViolations) {
            return constraintViolations.stream()
                    .map(constraintViolation -> new ConstraintViolationError(
                            constraintViolation.getPropertyPath().toString(),
                            constraintViolation.getInvalidValue().toString(),
                            constraintViolation.getMessage()))
                    .collect(Collectors.toList());
        }
    }
}