public class FileUploadController : ApiController    {         public async Task<HttpResponseMessage> Post()        {             // 检查是传文否是 multipart/form-data            if (!Request.Content.IsMimeMultipartContent("form-data"))                throw new HttpResponseException(HttpStatusCode.UnsupportedMediaType);            HttpResponseMessage response = null;            try            {                 // 设置上传目录                var provider = new MultipartFormDataStreamProvider(@"F:\StudyProject\webapi2demo\CSdemo\UpLoad");                // 接收数据，传文并保存文件                var bodyparts = await Request.Content.ReadAsMultipartAsync(provider);                response = Request.CreateResponse(HttpStatusCode.Accepted);            }            catch             {                 throw new HttpResponseException(HttpStatusCode.BadRequest);             }            return response;        }             }