BasicErrorController로 에러 전달하지 않는 방법

35 min readApr 10, 2024

여러 방식으로 예외를 처리할 수 있다.

@ResponseStatus, ResponseStatusException: BasicErrorController로 에러 전달
@ExceptionHandler: 에러가 BasicErrorController로 전달되지 않음

어떤 방식을 사용하냐에 따라 에러가 BasicErrorController로 전달되거나 그렇지 않은데 ResponseEntityExceptionHandler를 사용하면 Spring MVC Exception도 BasicErrorController로 전달하지 않고 처리할 수 있다.

BasicErrorController

예외에 대한 별도의 설정이 없다면 BasicErrorController로 전달된다.

@Controller
@RequestMapping("${server.error.path:${error.path:/error}}")
public class BasicErrorController extends AbstractErrorController {

  private final ErrorProperties errorProperties;

  @RequestMapping
  public ResponseEntity<Map<String, Object>> error(HttpServletRequest request) {
      HttpStatus status = getStatus(request);
      if (status == HttpStatus.NO_CONTENT) {
          return new ResponseEntity<>(status);
      }
      Map<String, Object> body = getErrorAttributes(request, getErrorAttributeOptions(request, MediaType.ALL));
      return new ResponseEntity<>(body, status);
 }

WAS로부터 에러 요청을 받으면 그 상태를 ResponseEntity로 응답한다.

server:
  error:
    path: /error

[nio-1234-exec-2] o.s.web.servlet.DispatcherServlet        : 
"ERROR" dispatch for GET "/error", parameters={}, headers={masked} in DispatcherServlet 'dispatcherServlet'

에러 경로의 기본 설정이 /error 이므로 예외가 발생하면 /error로 에러 요청을 전달한다. 이는 스프링 부트의 WebMvcAutoConfiguration를 통해 자동 설정되는 WAS의 설정이다.

public class WebMvcAutoConfiguration {

  @Override
  protected ExceptionHandlerExceptionResolver createExceptionHandlerExceptionResolver() {
      if (this.mvcRegistrations != null) {
         ExceptionHandlerExceptionResolver resolver = this.mvcRegistrations
                                    .getExceptionHandlerExceptionResolver();
         if (resolver != null) {
            return resolver;
         }
      }
      return super.createExceptionHandlerExceptionResolver();
}

일반적인 요청 흐름과 그 과정에서 에러가 발생해 BasicErrorController로 전달되는 흐름은 다음과 같다.

일반적인 요청 흐름은 다음과 같다.

WAS ➝ filter ➝ DispatcherServlet ➝ interceptor ➝ controller(요청 처리)

예외가 Controller를 넘어가면 그 흐름은 다음과 같다.

contoller ➝ interceptor ➝ DispatcherServlet ➝ filter ➝ WAS

WAS로 전달된 예외는 다음 과정을 통해 처리된다.

WAS ➝ filter ➝ DispatcherServlet ➝ interceptor ➝ controller(BasicErrorController)

즉, 별도로 예외 처리를 하지 않으면 에러를 받은 WAS는 다시 BasicErrorController로 전달하는 과정이 발생해 컨트롤러로 총 2번 접근하게 된다.

ExceptionResolver

우선순위가 높은 순서대로 예외 처리기는 다음과 같다.

ExceptionHandlerExceptionResolver: @ExceptionHandler 처리
ResponseStatusExceptionResolver: @ResponseStatus 또는 ResponseStatusException으로 처리
DefaultHandlerExceptionResolver: 스프링 내부의 기본 예외 처리

ExceptionHandlerExceptionResolver를 사용해 예외를 처리하면 에러가 BasicErrorController로 전달되지 않는다.

ResponseStatusExceptionResolver, DefaultHandlerExceptionResolver는 response.sendError를 통해 에러를 전달하므로 WAS는 /error 오류 페이지를 다시 요청한다. 즉, BasicErrorController로 에러를 전달한다.

아래 작성한 모든 테스트는 예외가 컨트롤러 밖으로 넘어가면 어떻게 처리되는지 확인한다.

ExceptionHandlerExceptionResolver

ExceptionResolver 중 가장 우선순위가 높으며 @ExcetpionHandler에 추가된 예외를 처리한다.

@ExcetpionHandler

@RestController
public class TestController {
    
    @GetMapping("/exception-test")
    public ResponseEntity<?> exceptionTest() {
        throw new CustomException(ExceptionCode.NOT_FOUND_ACCOUNT);
    }

    @ExceptionHandler(CustomException.class)
    public ResponseEntity<?> handleCustomException(CustomException e) {
        return handleExceptionInternal(e.getExceptionCode());
    }

@ExceptionHandler는 전체 애플리케이션에 대해 전역적으로 활성화되지 않고 특정 컨트롤러에서만 작동한다. @ControllerAdvice를 추가로 사용하면 여러 @ExceptionHandler를 global error handling component로 통합할 수 있다.

@ControllerAdvice, @RestControllerAdvice

@ControllerAdvice, @ResetControllerAdvice는 예외를 전역적으로 처리한다. 뒤에 붙은 Advice는 Spring AOP에서의 부가 기능을 의미하는 것 같다.

@ControllerAdvice는 @ExceptionHandler, @InitBinder 또는 @ModelAttribute로 정의된 메서드가 모든 @Controller 클래스를 공유할 수 있도록 한다.

@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@ControllerAdvice
@ResponseBody
public @interface RestControllerAdvice {...}

@RestControllerAdvice 코드를 보면 @ControllerAdvice가 추가되어있어 같은 기능을 제공하며, @ResponseBody가 추가되어 JSON으로 응답한다.

@RestControllerAdvice
public class GlobalExceptionHandler {

    @ExceptionHandler(CustomException.class)
    public ResponseEntity<?> handleCustomException(CustomException e) {
        return handleExceptionInternal(e.getExceptionCode());
    }

    private ResponseEntity<?> handleExceptionInternal(ExceptionCode exceptionCode) {
        return ResponseEntity.status(exceptionCode.getHttpStatus())
                .body(createExceptionResponse(exceptionCode));
    }

위와 같이 작성하고 ExceptionHandler에 추가한 CustomException(RuntimeException)을 던지면 ExceptionHandlerExceptionResolver가 예외를 처리한다.

[nio-1234-exec-1] .m.m.a.ExceptionHandlerExceptionResolver : 
Using @ExceptionHandler com...GlobalExceptionHandler#handleCustomException(CustomException)

[nio-1234-exec-1] o.s.web.method.HandlerMethod             : 
Arguments: [com...exception.CustomException]

[nio-1234-exec-1] o.s.w.s.m.m.a.HttpEntityMethodProcessor  : 
Writing [com...response.ExceptionResponse@3529a301]

[nio-1234-exec-1] .m.m.a.ExceptionHandlerExceptionResolver : 
Resolved [com...exception.CustomException]

[nio-1234-exec-1] o.s.web.servlet.DispatcherServlet        : 
Completed 400 BAD_REQUEST, headers={masked}

ExceptionHandlerExceptionResolver가 예외를 처리하며 BasicErrorController로 전달되지 않고, 작성한 handleCustomException 메서드로 전달된다.

Failed to complete request

만약 CustomException(Runtime Exception)을 ExcetpionHandler에 등록하지 않고 던지면 해당 예외를 처리할 handler를 찾을 수 없어서 에러가 발생하고 BasicErrorController로 전달된다.

[nio-1234-exec-1] o.a.c.c.C.[.[.[/].[dispatcherServlet]    : 
Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception 
[Request processing failed: com...CustomException] with root cause

com...exception.CustomException: null

[nio-1234-exec-1] o.a.c.c.C.[Tomcat].[localhost]           : 
Processing ErrorPage[errorCode=0, location=/error]

BasicErrorController에서 500 (Internal Server Error) 상태를 리턴한다.

ResponseEntityExceptionHandler

Handle all exceptions raised within Spring MVC handling of the request.

public abstract class ResponseEntityExceptionHandler implements MessageSourceAware {

  @ExceptionHandler({
     HttpRequestMethodNotSupportedException.class,
     HttpMediaTypeNotSupportedException.class,
     HttpMediaTypeNotAcceptableException.class,
     MissingPathVariableException.class,
     MissingServletRequestParameterException.class,
     MissingServletRequestPartException.class,
     ServletRequestBindingException.class,
     MethodArgumentNotValidException.class,
     HandlerMethodValidationException.class,
     NoHandlerFoundException.class,
     NoResourceFoundException.class,
     AsyncRequestTimeoutException.class,
     ErrorResponseException.class,
     MaxUploadSizeExceededException.class,
     ConversionNotSupportedException.class,
     TypeMismatchException.class,
     HttpMessageNotReadableException.class,
     HttpMessageNotWritableException.class,
     MethodValidationException.class,
     BindException.class
  })  
  @Nullable
  public final ResponseEntity<Object> handleException(Exception ex, WebRequest request) throws Exception {
      if (ex instanceof HttpRequestMethodNotSupportedException subEx) {
          return handleHttpRequestMethodNotSupported(subEx, subEx.getHeaders(), subEx.getStatusCode(), request);
      } else if (ex instanceof HttpMediaTypeNotSupportedException subEx) {
          return handleHttpMediaTypeNotSupported(subEx, subEx.getHeaders(), subEx.getStatusCode(), request);
      } ... 생략

      HttpHeaders headers = new HttpHeaders();
      if (ex instanceof ConversionNotSupportedException theEx) {
          return handleConversionNotSupported(theEx, headers, HttpStatus.INTERNAL_SERVER_ERROR, request);
      } else if (ex instanceof TypeMismatchException theEx) {
          return handleTypeMismatch(theEx, headers, HttpStatus.BAD_REQUEST, request);
      } ... 생략
      else {
          // Unknown exception, typically a wrapper with a common MVC exception as cause
          // (since @ExceptionHandler type declarations also match nested causes):
          // We only deal with top-level MVC exceptions here, so let's rethrow the given
          // exception for further processing through the HandlerExceptionResolver chain.
         throw ex;
      }
}

ResponseEntityExceptionHandler 코드 내 ExceptionHandler에 추가한 예외를 handleException 메서드에서 처리시키는데 예외에 맞는 세부 처리를 진행한 후 handleExceptionInternal 메서드에서 ResponseEntity 객체를 생성한다.

@Nullable
protected ResponseEntity<Object> handleExceptionInternal(
        Exception ex, @Nullable Object body, 
        HttpHeaders headers, HttpStatusCode statusCode, WebRequest request) {

    if (request instanceof ServletWebRequest servletWebRequest) {
        HttpServletResponse response = servletWebRequest.getResponse();
    // 생략
    if (statusCode.equals(HttpStatus.INTERNAL_SERVER_ERROR) && body == null) {
        request.setAttribute(WebUtils.ERROR_EXCEPTION_ATTRIBUTE, ex, WebRequest.SCOPE_REQUEST);
    }
    return createResponseEntity(body, headers, statusCode, request);
}

protected ResponseEntity<Object> createResponseEntity(
                          @Nullable Object body, HttpHeaders headers, 
                          HttpStatusCode statusCode, WebRequest request) {

    return new ResponseEntity<>(body, headers, statusCode);
}

ResponseEntity를 return 시켜, BasicErrorController로 에러를 보내지 않는다.

@RestControllerAdvice
public class GlobalExceptionHandler extends ResponseEntityExceptionHandler {

    @ExceptionHandler(AccountCustomException.class)
    public ResponseEntity<?> handleCustomException(AccountCustomException e) {
        return handleExceptionInternal(e.getExceptionCode());
    }

ResponseEntityExceptionHandler를 상속한 상태에서 ResponseEntityExceptionHandler 내 ExceptionHandler에 등록된 예외를 던지면 처리 과정은 다음과 같다.

[nio-1234-exec-2] .m.m.a.ExceptionHandlerExceptionResolver : 
Using @ExceptionHandler com...GlobalExceptionHandler#handleException(Exception, WebRequest)

[nio-1234-exec-2] o.s.web.method.HandlerMethod : 
Arguments: [org.springframework.web.context.request.async.AsyncRequestTimeoutException, 
            ServletWebRequest: uri=/exception-test;client=0:0:0:0:0:0:0:1]

[nio-1234-exec-2] o.s.w.s.m.m.a.HttpEntityMethodProcessor : 
Writing [ProblemDetail[type='about:blank', title='Service Unavailable', 
      status=503, detail='null', instance='/exception-test', properties='null']]

[nio-1234-exec-2] .m.m.a.ExceptionHandlerExceptionResolver : 
Resolved [org.springframework.web.context.request.async.AsyncRequestTimeoutException]

[nio-1234-exec-2] o.s.web.servlet.DispatcherServlet : 
Completed 503 SERVICE_UNAVAILABLE, headers={masked}

ExceptionHandlerExceptionResolver가 예외를 처리하며 BasicErrorController로 전달되지 않는다.

만약 ResponseEntityExceptionHandler를 상속하지 않고 AsyncRequestTimeoutException.class를 던지면 DefaultHandlerExceptionResolver가 처리한다.

DefaultHandlerExceptionResolver

여러 ExceptionResolver 중 DefaultHandlerExceptionResolver가 가장 우선순위가 낮으며, 지원하는 예외는 다음과 같다.

ResponseEntityExceptionHandler 내 ExceptionHandler에 등록된 예외와 동일하다. AsyncRequestTimeoutException이 발생하면 500 상태로 리턴하는 것이 아니라 DefaultHandlerExceptionResolver가503 상태로 변경해 리턴한다.

public class DefaultHandlerExceptionResolver extends AbstractHandlerExceptionResolver {

  protected ModelAndView handleErrorResponse(ErrorResponse errorResponse,
       HttpServletRequest request, HttpServletResponse response, @Nullable Object handler) throws IOException {

    if (!response.isCommitted()) {
       HttpHeaders headers = errorResponse.getHeaders();
       headers.forEach((name, values) -> values.forEach(value -> response.addHeader(name, value)));

       int status = errorResponse.getStatusCode().value();
       String message = errorResponse.getBody().getDetail();
       if (message != null) {
          response.sendError(status, message);
       }
       else {
          response.sendError(status);
       }
    }
    else if (logger.isWarnEnabled()) {
       logger.warn("Ignoring exception, response committed already: " + errorResponse);
    }
    return new ModelAndView();
  }

DefaultHandlerExceptionResolver가 예외를 처리하면 response.sendError()를 호출한다.

[nio-1234-exec-1] .w.s.m.s.DefaultHandlerExceptionResolver : 
Resolved [org.springframework.web.context.request.async.AsyncRequestTimeoutException]

[nio-1234-exec-1] o.s.web.servlet.DispatcherServlet : 
Completed 503 SERVICE_UNAVAILABLE, headers={}

[nio-1234-exec-1] o.s.web.servlet.DispatcherServlet : 
"ERROR" dispatch for GET "/error", parameters={}, headers={masked} in DispatcherServlet 'dispatcherServlet'

[nio-1234-exec-1] s.w.s.m.m.a.RequestMappingHandlerMapping : 
2 matching mappings: [{ [/error]}, { [/error], produces [text/html]}]

[nio-1234-exec-1] o.s.b.f.s.DefaultListableBeanFactory : 
Returning cached instance of singleton bean 'basicErrorController'

[nio-1234-exec-1] s.w.s.m.m.a.RequestMappingHandlerMapping : 
Mapped to org.springframework.boot.autoconfigure.web.servlet.error.BasicErrorController#error(HttpServletRequest)

[nio-1234-exec-1] o.s.w.s.m.m.a.HttpEntityMethodProcessor : 
Writing [{timestamp=..., status=503, error=Service Unavailable, message=No message available, path=/exception-test}]

[nio-1234-exec-1] o.s.web.servlet.DispatcherServlet : 
Exiting from "ERROR" dispatch, status 503, headers={masked}

DefaultHandlerExceptionResolver가 예외를 처리하며 BasicErrorController를 통해 에러를 응답한다. 중요한 것은 ResponseEntityExceptionHandler가 존재하지 않을 때다.

Failed to complete request

ResponseEntityExceptionHandler 또는 DefaultHandlerExceptionResolver가 관리하지 않은 Exception을 던지면 처리 과정은 다음과 같다.

[nio-1234-exec-2] o.s.web.servlet.DispatcherServlet : 
Failed to complete request
java.lang.IllegalArgumentException: null

[nio-1234-exec-2] o.a.c.c.C.[.[.[/].[dispatcherServlet] : 
Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception 
[Request processing failed: java.lang.IllegalArgumentException] with root cause
java.lang.IllegalArgumentException: null

[nio-1234-exec-2] o.a.c.c.C.[Tomcat].[localhost] : 
Processing ErrorPage[errorCode=0, location=/error]

[nio-1234-exec-2] o.s.web.servlet.DispatcherServlet : 
"ERROR" dispatch for GET "/error", parameters={}, headers={masked} in DispatcherServlet 'dispatcherServlet'

[nio-1234-exec-2] o.s.b.f.s.DefaultListableBeanFactory : 
Returning cached instance of singleton bean 'basicErrorController'

[nio-1234-exec-2] s.w.s.m.m.a.RequestMappingHandlerMapping : 
Mapped to org.springframework.boot.autoconfigure.web.servlet.error.BasicErrorController#error(HttpServletRequest)

그 어떤 ExcetpionResolver도 예외를 처리하지 않고 DispatherServlet으로 넘겨진다.

ResponseStatusExceptionResolver

@ResponseStatus 또는 ResponseStatusException를 처리한다.

@ResponseStatus(code = HttpStatus.BAD_REQUEST, reason = "test-reason")
public class CustomException extends RuntimeException {}

@ResponseStatus를 사용하면 CustomException을 던질 때마다 같은 상태와 메시지를 반환한다. 이는 ResponseStatusException으로 해결할 수 있다.

throw new ResponseStatusException(HttpStatus.BAD_REQUEST, "test-reason");

ResponseStatusException을 사용하면 HttpStatus, Reason을 자유롭게 선택할 수 있다.

public class ResponseStatusExceptionResolver extends AbstractHandlerExceptionResolver implements MessageSourceAware {

  protected ModelAndView applyStatusAndReason(int statusCode, @Nullable String reason, HttpServletResponse response)
                                               throws IOException {

    if (!StringUtils.hasLength(reason)) {
        response.sendError(statusCode);
    }
    else {
        String resolvedReason = (this.messageSource != null ?
          this.messageSource.getMessage(reason, null, reason, LocaleContextHolder.getLocale()) :
          reason);
        response.sendError(statusCode, resolvedReason);
    }
    return new ModelAndView();
  }

ResponseStatusExceptionResolver로 예외를 처리하면 response.sendError()를 호출한다.

[nio-1234-exec-1] .w.s.m.a.ResponseStatusExceptionResolver : 
Resolved [org.springframework.web.server.ResponseStatusException: 400 BAD_REQUEST "test-reason"]
// Resolved [com.kurly.kurlyaccount.exception.CustomException] -> @ResponseStatus 사용 시

[nio-1234-exec-1] o.s.web.servlet.DispatcherServlet        : 
Completed 400 BAD_REQUEST, headers={}

[nio-1234-exec-1] o.a.c.c.C.[Tomcat].[localhost]           : 
Processing ErrorPage[errorCode=0, location=/error]

[nio-1234-exec-2] o.s.web.servlet.DispatcherServlet        : 
"ERROR" dispatch for GET "/error", parameters={}, headers={masked} in DispatcherServlet 'dispatcherServlet'

[nio-1234-exec-2] o.s.b.f.s.DefaultListableBeanFactory     : 
Returning cached instance of singleton bean 'basicErrorController'

[nio-1234-exec-2] s.w.s.m.m.a.RequestMappingHandlerMapping : 
Mapped to org.springframework.boot.autoconfigure.web.servlet.error.BasicErrorController#error(HttpServletRequest)

[nio-1234-exec-2] o.s.w.s.m.m.a.HttpEntityMethodProcessor  : 
Writing [{timestamp=..., status=400, error=Bad Request, message=test-reason, path=/exception-test}]

@ResponseStatus를 설정한 예외 또는 ResponseStatusException을 던지면 ResponseStatusExceptionResolver가 예외를 처리하며 BasicErrorController를 통해 응답하는 것을 확인할 수 있다.

ResponseEntityExceptionHandler + ResponseStatusException

@ResponseStatus를 설정한 예외 또는 ResponseStatusException을 던지면 ResponseStatusExceptionResolver가 예외를 처리한다.

만약 ResponseEntityExceptionHandler를 상속한 상태에서 @ResponseStatus를 설정한 예외 또는 ResponseStatusException을 던지면 ExceptionHandlerExceptionResolver가 예외를 처리해 BasicErrorController로 에러가 전달되지 않는다.

[nio-1234-exec-1] .m.m.a.ExceptionHandlerExceptionResolver : 
Using @ExceptionHandler com...exception.GlobalExceptionHandler#handleException(Exception, WebRequest)

[nio-1234-exec-1] o.s.web.method.HandlerMethod             : 
Arguments: [org.springframework.web.server.ResponseStatusException: 400 BAD_REQUEST "test-reason", ServletWebRequest: uri=/exception-test;client=0:0:0:0:0:0:0:1]

[nio-1234-exec-1] o.s.w.s.m.m.a.HttpEntityMethodProcessor  : 
Writing [ProblemDetail[type='about:blank', title='Bad Request', status=400, detail='test-reason', instance='/exception-test', properties='null']]

[nio-1234-exec-1] .m.m.a.ExceptionHandlerExceptionResolver : 
Resolved [org.springframework.web.server.ResponseStatusException: 400 BAD_REQUEST "test-reason"]

[nio-1234-exec-1] o.s.web.servlet.DispatcherServlet        : 
Completed 400 BAD_REQUEST, headers={masked}

ResponseEntityExceptionHandle.handleException에서 ResponseStatusException를 처리한다.

public abstract class ResponseEntityExceptionHandler implements MessageSourceAware {

  @ExceptionHandler({
     HttpRequestMethodNotSupportedException.class,
     HttpMediaTypeNotSupportedException.class,
     ...
  })
  @Nullable
  public final ResponseEntity<Object> handleException(Exception ex, WebRequest request) throws Exception {
      if (ex instanceof HttpRequestMethodNotSupportedException subEx) {
          return handleHttpRequestMethodNotSupported(subEx, subEx.getHeaders(), subEx.getStatusCode(), request);
      } else if (ex instanceof HttpMediaTypeNotSupportedException subEx) {
          return handleHttpMediaTypeNotSupported(subEx, subEx.getHeaders(), subEx.getStatusCode(), request);
      } ... 생략

      HttpHeaders headers = new HttpHeaders();
      if (ex instanceof ConversionNotSupportedException theEx) {
          return handleConversionNotSupported(theEx, headers, HttpStatus.INTERNAL_SERVER_ERROR, request);
      } else if (ex instanceof TypeMismatchException theEx) {
          return handleTypeMismatch(theEx, headers, HttpStatus.BAD_REQUEST, request);
      } ... 생략
      else {
          // Unknown exception, typically a wrapper with a common MVC exception as cause
          // (since @ExceptionHandler type declarations also match nested causes):
          // We only deal with top-level MVC exceptions here, so let's rethrow the given
          // exception for further processing through the HandlerExceptionResolver chain.
         throw ex;
      }
}

BasicErrorController로 에러 전달하지 않는 방법

BasicErrorController

ExceptionResolver

ExceptionHandlerExceptionResolver

@ExcetpionHandler

@ControllerAdvice, @RestControllerAdvice

Failed to complete request

ResponseEntityExceptionHandler

DefaultHandlerExceptionResolver

Failed to complete request

ResponseStatusExceptionResolver

ResponseEntityExceptionHandler + ResponseStatusException

Written by nayoung