/// <summary>
        /// 项目文件夹下路径  返回流类型数据，如：图片类型
        /// </summary>
        /// <returns></returns>
        public HttpResponseMessage GetImg()
        {  //  ~/ ImageFile / 001.png
            //项目文件夹下路径
            var imgPath = System.Web.Hosting.HostingEnvironment.MapPath("~/ImageFile/2.jpg");
           // 从图片中读取byte
            var imgByte = File.ReadAllBytes(imgPath);
           // 从图片中读取流
            var imgStream = new MemoryStream(File.ReadAllBytes(imgPath));
            var resp = new HttpResponseMessage(HttpStatusCode.OK)
            {
                Content = new StreamContent(imgStream)
                //或者
              //  Content = new ByteArrayContent(imgByte)
            };
            resp.Content.Headers.ContentType = new MediaTypeHeaderValue("image/jpg");
            return resp;
        }

 [HttpGet]
        public HttpResponseMessage SelectUploadFile()
        {

            Image img = Image.FromFile(@"C:\ImageFile\2.jpg");

            MemoryStream ms = new MemoryStream();
            img.Save(ms, System.Drawing.Imaging.ImageFormat.Png);
            HttpResponseMessage result = new HttpResponseMessage(HttpStatusCode.OK);
            result.Content = new ByteArrayContent(ms.ToArray());
            result.Content.Headers.ContentType = new MediaTypeHeaderValue("image/png"); //设置http响应上的Content-Type 为image/Png媒体类型

            return result;

        }