spring-boot REST POST API发送文件

我刚接触Spring并尝试创建REST POST API，以便用户可以将文件发送到服务器。

@RequestMapping(value = "/order", method = RequestMethod.POST)
public String create(@RequestParam("file") MultipartFile file) {        
        System.out.println("---------INSIDE ORDER----------");
        return "file succesfully received!";
}

但是，当我通过上传order.txt文件并选择表格数据（在邮递员中）调用此API时，出现此错误

{
  "timestamp": 1474129488458,
  "status": 400,
  "error": "Bad Request",
  "exception": "org.springframework.web.multipart.support.MissingServletRequestPartException",
  "message": "Required request part 'file' is not present",
  "path": "/order"
}