实践案例包括两个项目，服务提供者项目名：upload-service，调用服务项目名：upload-client，主要给出两个服务之间的调用过程，文件上传功能不提供

项目框架：spring-boot 2.0.1.RELEASE、spring-cloud Finchley.RELEASE

依赖：

  <dependency>
   <groupId>io.github.openfeign.form</groupId>
   <artifactId>feign-form</artifactId>
   <version>3.0.3</version>
  </dependency>
  <dependency>
   <groupId>io.github.openfeign.form</groupId>
   <artifactId>feign-form-spring</artifactId>
   <version>3.0.3</version>
  </dependency>
  <dependency>
   <groupId>commons-fileupload</groupId>
   <artifactId>commons-fileupload</artifactId>
   <version>1.3.3</version>
  </dependency>

创建FeignClient接口（用于指定远程调用的服务）

// 申明这是一个Feign客户端，并且指明服务id
@FeignClient(value = "com-spring-caclulate") 
public interface CacluFeignClient {

 // 这里定义了类似于SpringMVC用法的方法，就可以进行RESTful的调用了
 @RequestMapping(value = "/caclu/{num}", method = RequestMethod.GET)
 public Item caclulate(@PathVariable("num") Integer num);

} 

一.文件上传服务upload-service

1.控制层

@Slf4j
@CrossOrigin
@RestController
@RequestMapping("/ftp")
@Api(description = "文件上传控制")
public class FtpFileController {

 @Autowired
 private FtpFileService ftpFileService;

 /**
  * FTP文件上传
  *
  * @return
  */
 @PostMapping(value = "/uploadFile", consumes = MediaType.MULTIPART_FORM_DATA_VALUE)
 public FtpApiResponse<FtpUploadResDTO> uploadFileFTP(@RequestPart(value = "file") MultipartFile file,
               @RequestParam("logId") String logId) {
  FtpApiResponse<FtpUploadResDTO> result = new FtpApiResponse<>();
  LogUtil.updateLogId(logId);
  try {
   log.info("文件上传开始!}");
   Long startTime = System.currentTimeMillis();
   FtpUploadResDTO resDTO = ftpFileService.uploadFile(file);
   result.setData(resDTO);
   result.setSuccess(true);
   result.setTimeInMillis(System.currentTimeMillis() - startTime);
   log.info("文件上传结束 resDTO：{}，耗时:{}", resDTO, (System.currentTimeMillis() - startTime));
  } catch (ServiceException e){
   result.setSuccess(false);
   result.setErrorCode(ErrorMsgEnum.FILE_UPLOAD_EXCEPTION.getCode());
   result.setErrorMsg(ErrorMsgEnum.FILE_UPLOAD_EXCEPTION.getMsg());
  } catch (Exception e) {
   result.setSuccess(false);
   result.setErrorCode(ErrorMsgEnum.SYSTEM_ERROR.getCode());
   result.setErrorMsg(ErrorMsgEnum.SYSTEM_ERROR.getMsg());
   log.info("文件上传失败 Exception：{}", Throwables.getStackTraceAsString(e));
  }
  return result;
 }
}

2.业务层

@Service
@Slf4j
public class FtpFileService {

 @Autowired
 private FtpFileManager ftpFileManager;

 /**
  * 上传文件
  *
  * @param file
  * @return
  */
 public FtpUploadResDTO uploadFile(MultipartFile file) {
  try {
   //判断上传文件是否为空
   if (null == file || file.isEmpty() || file.getSize() == 0) {
    log.info("传入的文件为空,file:{}", file);
    throw new ServiceException(ErrorMsgEnum.EMPTY_FILE);
   }
   //文件上传至ftp服务目录
   FtpFileRecordDO ftpFileRecordDO = ftpFileManager.fileUploadToFtp(file);
   if (null == ftpFileRecordDO) {
    log.info("文件上传至ftp服务目录异常");
    throw new ServiceException(ErrorMsgEnum.FILE_UPLOAD_TO_FTP_EXCEPTION);
   }
   return ftpFileManager.addFileRecord(ftpFileRecordDO);
  } catch (Exception e) {
   log.error("业务异常,case", e);
   throw new ServiceException(ErrorMsgEnum.SYSTEM_ERROR);
  }
 }
}