[HttpPost] public Task<Hashtable> ImgUpload() {     // 检查是否是 multipart/form-data     if (!Request.Content.IsMimeMultipartContent("form-data"))         throw new HttpResponseException(HttpStatusCode.UnsupportedMediaType);     //文件保存目录路径     string SaveTempPath = "~/SayPlaces/" + "/SayPic/SayPicTemp/";     String dirTempPath = HttpContext.Current.Server.MapPath(SaveTempPath);     // 设置上传目录     var provider = new MultipartFormDataStreamProvider(dirTempPath);     //var queryp = Request.GetQueryNameValuePairs();//获得查询字符串的键值集合     var task = Request.Content.ReadAsMultipartAsync(provider).         ContinueWith<Hashtable>(o =>         {             Hashtable hash = new Hashtable();             hash["error"] = 1;             hash["errmsg"] = "上传出错";             var file = provider.FileData[0];//provider.FormData             string orfilename = file.Headers.ContentDisposition.FileName.TrimStart('"').TrimEnd('"');             FileInfo fileinfo = new FileInfo(file.LocalFileName);                                 //最大文件大小             int maxSize = 10000000;             if (fileinfo.Length <= 0)             {                 hash["error"] = 1;                 hash["errmsg"] = "请选择上传文件。";             }             else if (fileinfo.Length > maxSize)             {                 hash["error"] = 1;                 hash["errmsg"] = "上传文件大小超过限制。";             }             else             {                 string fileExt = orfilename.Substring(orfilename.LastIndexOf('.'));                 //定义允许上传的文件扩展名                 String fileTypes = "gif,jpg,jpeg,png,bmp";                 if (String.IsNullOrEmpty(fileExt) || Array.IndexOf(fileTypes.Split(','), fileExt.Substring(1).ToLower()) == -1)                 {                     hash["error"] = 1;                     hash["errmsg"] = "上传文件扩展名是不允许的扩展名。";                 }                 else                 {                     String ymd = DateTime.Now.ToString("yyyyMMdd", System.Globalization.DateTimeFormatInfo.InvariantInfo);                     String newFileName = DateTime.Now.ToString("yyyyMMddHHmmss_ffff", System.Globalization.DateTimeFormatInfo.InvariantInfo);                     fileinfo.CopyTo(Path.Combine(dirTempPath, newFileName + fileExt), true);                     fileinfo.Delete();                     hash["error"] = 0;                     hash["errmsg"] = "上传成功";                 }             }             return hash;         });     return task; }