最近代码升级，springcloud1.x版本升级为2.x版本，同时feign变成了openfeign,业务上是从a服务调用b服务接口再去调用c服务。
发现文件传不上去，a服务就报错com.fasterxml.jackson.databind.JsonMappingException: 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"])
排查问题后，在b服务接口加上参数
consumes = MediaType.MULTIPART_FORM_DATA_VALUE
示例接口如下：
@RequestMapping(value = "/importFile", method = RequestMethod.POST, consumes = MediaType.MULTIPART_FORM_DATA_VALUE)
BaseResult importProductTxt(@RequestPart(value = "file", required = false) MultipartFile file, @RequestParam("filename") String filename);
还遇到一个上传文件的接口，报错HttpMediaTypeNotAcceptableException Could not find acceptable representation
是因为单文件上传的时候，要用@RequestPart注解
