title: Why can @requestparam get file upload data in SpringMVC?
body: <p>@requestparam functions like request.getquerystring (). Why does she receive a multipart/form-data type contentType when @requestbody cannot?Please tell me why?</p>
  
  <pre class="lang-java prettyprint-override"><code>    @PostMapping(value = "/uploadFileByUserTrainId", consumes = "multipart/form-data")
      @Student({Student.Authority.A, Student.Authority.B, Student.Authority.C})
      public WebMessage uploadFileByUserTrainId(
              @RequestParam(value = "document", required = false) MultipartFile multipartFile,
              @RequestParam(value = "documetnRe", required = false) MultipartFile multipartFileRe,
              @RequestParam("id") long id,
              @RequestParam(value = "documentFileType", required = false) String fileType,
              @RequestParam(value = "documentFileReType", required = false) String fileReType,
              HttpServletRequest httpServletRequest) {
        // todo
      }
  </code></pre>