C#上传图片，同时生成缩略图

C#代码

    /// <summary>
    /// uploadJaeyi 的摘要说明
    /// </summary>
    public class uploadJaeyi : IHttpHandler
    {
        ILog log = LogManager.GetLogger(System.Reflection.MethodBase.GetCurrentMethod().DeclaringType);
        public void ProcessRequest(HttpContext context)
        {
            string serverPath = context.Server.MapPath("/Upload/Jaeyi/");
            if (!Directory.Exists(serverPath))
            {
                Directory.CreateDirectory(serverPath);
            }
            string serverSmallPath = context.Server.MapPath("/Upload/Jaeyi/Small/");
            if (!Directory.Exists(serverSmallPath))
            {
                Directory.CreateDirectory(serverSmallPath);
            }
            HttpFileCollection files = context.Request.Files;
            if (files.Count > 0)
            {
                for (int i = 0; i < files.Count; i++)
                {
                    try
                    {
                        System.IO.Stream stream = files[i].InputStream;
                        string fileFullName = files[i].FileName;
                        int index = fileFullName.LastIndexOf("\");
                        string fileName = fileFullName.Substring(index + 1);
                        //得到指定上传文件的字节输入流   
                        int imgDataLen = (int)(stream.Length);
                        byte[] imgData = new byte[imgDataLen];
                        int n = stream.Read(imgData, 0, imgDataLen);
                        stream.Close();
                        FileStream fs = new FileStream(serverPath + fileName, FileMode.OpenOrCreate, FileAccess.Write);
                        fs.Write(imgData, 0, imgDataLen);
                        fs.Flush();
                        fs.Close();


                        string oldpath = serverPath + fileName;
                        string newpath = serverSmallPath + fileName;
                        MakeThumbnail(oldpath, newpath, 40, 40, "H");
                    }
                    catch (Exception ex)
                    {
                        log.Error("捷易拍照上传失败：" + ex);
                    }
                }
            }
        }

        /// <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 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
            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(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 Rectangle(0, 0, towidth, toheight),
                new Rectangle(x, y, ow, oh),
                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();
            }
        }

        public bool IsReusable
        {
            get
            {
                return false;
            }
        }
    }

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