我必须发出一个HTTPPOST请求，以从上传文件（.doc/.jpg等）的外部api获取“上传成功”通知。目前，我正在使用以下postman命令调用api：

这是我的控制器类：

@RestController
public class PushNotif {
    @Bean
    public RestTemplate restTemplate(RestTemplateBuilder builder) {
        return builder.build();
    }
    @Autowired
    RestTemplate restTemplate;
    private static Logger logger = LogManager.getLogger(PushNotif.class.getName());
   @RequestMapping(value = "/upload/notif", method = RequestMethod.POST)
   public String NotifStatus(@RequestParam("file") MultipartFile file) {
     final String url = "http://localhost:8080/upload";
     HttpHeaders headers = new HttpHeaders();
     headers.setAccept(Arrays.asList(MediaType.MULTIPART_FORM_DATA));
     HttpEntity<MultipartFile> entity = new HttpEntity<MultipartFile>(file, headers);
     return restTemplate.exchange(url, HttpMethod.POST, entity, 
            String.class).getBody();
}

}
但我得到内部服务器错误。

[Request processing failed; nested exception is org.springframework.http.converter.HttpMessageConversionException: Type definition error: [simple type, class java.io.FileDescriptor]; nested exception is com.fasterxml.jackson.databind.exc.InvalidDefinitionException: No serializer found for class java.io.FileDescriptor and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) (through reference chain: org.springframework.web.multipart.support.StandardMultipartHttpServletRequest$StandardMultipartFile["inputStream"]->java.io.FileInputStream["fd"])] with root cause
com.fasterxml.jackson.databind.exc.InvalidDefinitionException: No serializer found for class java.io.FileDescriptor and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) (through reference chain: org.springframework.web.multipart.support.StandardMultipartHttpServletRequest$StandardMultipartFile["inputStream"]->java.io.FileInputStream["fd"])

如何在rest中将http请求上传到文件（.doc/.jpg等）作为回报，我在客户端得到了通知（json）“post request successful”。请让我知道或指向我的任何参考。