图片上传处理Server端

 public ActionResult Upload()
        {
            HttpPostedFileBase file = Request.Files["Fdata"];//接受文件数据
            string FileName = Path.GetFileName(file.FileName);//获取文件名
            string FileExt = Path.GetExtension(FileName);//获取扩展名
            if (FileExt == ".jpg")
            {
                //file.SaveAs(Request.MapPath("/UploadFile/" + FileName));
                string dir = "/UploadFile/" + DateTime.Now.Year + "/" + DateTime.Now.Month + "/" + DateTime.Now.Day + "/";
                Directory.CreateDirectory(Request.MapPath(dir));//创建文件夹
                string FullDir = dir + GetStreamMD5(file.InputStream) + FileExt;//构建完整路径
                file.SaveAs(Request.MapPath(FullDir));//保存完整图片
                string ThumbnalPath = dir + Guid.NewGuid() + ".jpg";
                MakeThumbnail(Request.MapPath(FullDir), Request.MapPath(ThumbnalPath), 100, 100, "H");//保存缩略图
                using (Image img = Image.FromFile(Request.MapPath(ThumbnalPath)))
                {
                    return Json(new
                    {
                        imagePath = ThumbnalPath,
                        width = img.Width,
                        height = img.Height
                    });
                }

            }
            else
            {
                return Content("上传文件失败");
            }

        }



        /// <summary>
        /// 计算文件的MD5值
        /// </summary>
        /// <param name="filepath"></param>
        /// <returns></returns>
        public static String GetStreamMD5(Stream stream)
        {
            string strResult = "";
            string strHashData = "";
            byte[] arrbytHashValue;
            System.Security.Cryptography.MD5CryptoServiceProvider oMD5Hasher =
                new System.Security.Cryptography.MD5CryptoServiceProvider();
            arrbytHashValue = oMD5Hasher.ComputeHash(stream); //计算指定Stream 对象的哈希值
            //由以连字符分隔的十六进制对构成的String，其中每一对表示value 中对应的元素；例如“F-2C-4A”
            strHashData = System.BitConverter.ToString(arrbytHashValue);
            //替换-
            strHashData = strHashData.Replace("-", "");
            strResult = strHashData;
            return strResult;
        }

        #region 缩略图
        /// <summary>
        /// 生成缩略图
        /// </summary>
        /// <param name="originalImagePath">源图路径（物理路径）</param>
        /// <param name="thumbnailPath">缩略图路径（物理路径）</param>
        /// <param name="width">缩略图宽度</param>
        /// <param name="height">缩略图高度</param>
        /// <param name="mode">生成缩略图的方式</param>    
        public static void MakeThumbnail(string originalImagePath, string thumbnailPath, int width, int height, string mode)
        {
            System.Drawing.Image originalImage = System.Drawing.Image.FromFile(originalImagePath);

            int towidth = width;
            int toheight = height;

            int x = 0;
            int y = 0;
            int ow = originalImage.Width;
            int oh = originalImage.Height;

            switch (mode)
            {
                case "HW":  //指定高宽缩放（可能变形）                
                    break;
                case "W":   //指定宽，高按比例                    
                    toheight = originalImage.Height * width / originalImage.Width;
                    break;
                case "H":   //指定高，宽按比例
                    towidth = originalImage.Width * height / originalImage.Height;
                    break;
                case "Cut": //指定高宽裁减（不变形）                
                    if ((double)originalImage.Width / (double)originalImage.Height > (double)towidth / (double)toheight)
                    {
                        oh = originalImage.Height;
                        ow = originalImage.Height * towidth / toheight;
                        y = 0;
                        x = (originalImage.Width - ow) / 2;
                    }
                    else
                    {
                        ow = originalImage.Width;
                        oh = originalImage.Width * height / towidth;
                        x = 0;
                        y = (originalImage.Height - oh) / 2;
                    }
                    break;
                default:
                    break;
            }

            //新建一个bmp图片
            System.Drawing.Image bitmap = new System.Drawing.Bitmap(towidth, toheight);

            //新建一个画板
            System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(bitmap);

            //设置高质量插值法
            g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;

            //设置高质量,低速度呈现平滑程度
            g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;

            //清空画布并以透明背景色填充
            g.Clear(System.Drawing.Color.Transparent);

            //在指定位置并且按指定大小绘制原图片的指定部分
            g.DrawImage(originalImage, new System.Drawing.Rectangle(0, 0, towidth, toheight), new System.Drawing.Rectangle(x, y, ow, oh), System.Drawing.GraphicsUnit.Pixel);

            try
            {
                //以jpg格式保存缩略图
                bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Jpeg);
            }
            catch (System.Exception e)
            {
                throw e;
            }
            finally
            {
                originalImage.Dispose();
                bitmap.Dispose();
                g.Dispose();
            }
        }
        #endregion