AngularJS Spring Rest MissingServletRequestPartException必需的请求部分＆＃39; file＆＃39;不在场

Question

我尝试从UI上传文件并获得以下异常： 错误＆＃34;：＆＃34;错误请求＆＃34;，＆＃34;例外＆＃34;：＆＃34; org.springframework.web.multipart.support.MissingServletRequestPartException＆＃34;，＆＃34; message＆＃34 ;：＆＃34;必填请求部分＆＃39;文件＆＃39;不存在。＆＃34;

Javascript代码：

var fd = new FormData();
      fd.append("file", config.uploadFile);

      $http.post(url, fd, {
        transformRequest: angular.identity,
        headers: {'Content-Type': undefined}
      })

Controller code:
@RequestMapping(value = "/rest/data/upload", method = RequestMethod.POST,
            consumes = {"multipart/*"}, headers = "content-type=multipart/form-data")
    public void uploadFile(@RequestPart("file") MultipartFile file) throws Exception {
        this.fileService.uploadFile(file);
    }

我将此添加到AppConfig（在查看StackOverflow中的类似问题之后）：

@Bean
    public MultipartResolver multipartResolver() {
        CommonsMultipartResolver resolver=new CommonsMultipartResolver();
//        resolver.setDefaultEncoding("utf-8");
        resolver.setMaxInMemorySize(1048576);
        resolver.setMaxUploadSize(20971520);
        return resolver;
    }

这个问题仍然存在。任何见解/指示/帮助将不胜感激。

谢谢， AI