인프런 커뮤니티 질문&답변

안녕하세요. australialove19님, 공식 서포터즈 OMG입니다.

아래 내용을 참고해주세요.

/**
 * Resolves {@link Map} method arguments annotated with an @{@link RequestParam}
 * where the annotation does not specify a request parameter name.
 *
 * <p>The created {@link Map} contains all request parameter name/value pairs,
 * or all multipart files for a given parameter name if specifically declared
 * with {@link MultipartFile} as the value type. If the method parameter type is
 * {@link MultiValueMap} instead, the created map contains all request parameters
 * and all their values for cases where request parameters have multiple values
 * (or multiple multipart files of the same name).
 *
 * @author Arjen Poutsma
 * @author Rossen Stoyanchev
 * @author Juergen Hoeller
 * @since 3.1
 * @see RequestParamMethodArgumentResolver
 * @see HttpServletRequest#getParameterMap()
 * @see MultipartRequest#getMultiFileMap()
 * @see MultipartRequest#getFileMap()
 */
public class RequestParamMapMethodArgumentResolver implements HandlerMethodArgumentResolver {

   @Override
   public boolean supportsParameter(MethodParameter parameter) {
      RequestParam requestParam = parameter.getParameterAnnotation(RequestParam.class);
      return (requestParam != null && Map.class.isAssignableFrom(parameter.getParameterType()) &&
            !StringUtils.hasText(requestParam.name()));
   }

   @Override
   public Object resolveArgument(MethodParameter parameter, @Nullable ModelAndViewContainer mavContainer,
         NativeWebRequest webRequest, @Nullable WebDataBinderFactory binderFactory) throws Exception {

      ResolvableType resolvableType = ResolvableType.forMethodParameter(parameter);

      if (MultiValueMap.class.isAssignableFrom(parameter.getParameterType())) {
         // MultiValueMap
         Class<?> valueType = resolvableType.as(MultiValueMap.class).getGeneric(1).resolve();
         if (valueType == MultipartFile.class) {
            MultipartRequest multipartRequest = MultipartResolutionDelegate.resolveMultipartRequest(webRequest);
            return (multipartRequest != null ? multipartRequest.getMultiFileMap() : new LinkedMultiValueMap<>(0));
         }
         else if (valueType == Part.class) {
            HttpServletRequest servletRequest = webRequest.getNativeRequest(HttpServletRequest.class);
            if (servletRequest != null && MultipartResolutionDelegate.isMultipartRequest(servletRequest)) {
               Collection<Part> parts = servletRequest.getParts();
               LinkedMultiValueMap<String, Part> result = new LinkedMultiValueMap<>(parts.size());
               for (Part part : parts) {
                  result.add(part.getName(), part);
               }
               return result;
            }
            return new LinkedMultiValueMap<>(0);
         }
         else {
            Map<String, String[]> parameterMap = webRequest.getParameterMap();
            MultiValueMap<String, String> result = new LinkedMultiValueMap<>(parameterMap.size());
            parameterMap.forEach((key, values) -> {
               for (String value : values) {
                  result.add(key, value);
               }
            });
            return result;
         }
      }

      else {
         // Regular Map
         Class<?> valueType = resolvableType.asMap().getGeneric(1).resolve();
         if (valueType == MultipartFile.class) {
            MultipartRequest multipartRequest = MultipartResolutionDelegate.resolveMultipartRequest(webRequest);
            return (multipartRequest != null ? multipartRequest.getFileMap() : new LinkedHashMap<>(0));
         }
         else if (valueType == Part.class) {
            HttpServletRequest servletRequest = webRequest.getNativeRequest(HttpServletRequest.class);
            if (servletRequest != null && MultipartResolutionDelegate.isMultipartRequest(servletRequest)) {
               Collection<Part> parts = servletRequest.getParts();
               LinkedHashMap<String, Part> result = CollectionUtils.newLinkedHashMap(parts.size());
               for (Part part : parts) {
                  if (!result.containsKey(part.getName())) {
                     result.put(part.getName(), part);
                  }
               }
               return result;
            }
            return new LinkedHashMap<>(0);
         }
         else {
            Map<String, String[]> parameterMap = webRequest.getParameterMap();
            Map<String, String> result = CollectionUtils.newLinkedHashMap(parameterMap.size());
            parameterMap.forEach((key, values) -> {
               if (values.length > 0) {
                  result.put(key, values[0]);
               }
            });
            return result;
         }
      }
   }

}

참고

HandlerMethodArgumentResolver - 기본편 :: 레이피엘의 블로그 (tistory.com)

감사합니다.