使用fileupload上传图片后生成水印和缩略图

protected void Button1_Click(object sender, EventArgs e)
    {
        string fileContentType = FileUpload1.PostedFile.ContentType;
        if (fileContentType == "image/bmp" || fileContentType == "image/gif" || fileContentType == "image/jpeg")
        {
            string name = FileUpload1.PostedFile.FileName;
            FileInfo file = new FileInfo(name);
            string fileName = file.Name;
            string fileName_s = "s_" + file.Name;
            string fileName_sy = "st_" + file.Name;
            string fileName_syp = "syp_" + file.Name;
            string webFilePath = Server.MapPath("file/" + fileName);
            string webFilePath_s = Server.MapPath("file/" + fileName_s);
            string webFilePath_sy = Server.MapPath("file/" + fileName_sy);
            string webfilePath_syp = Server.MapPath("file/" + fileName_syp);
            string webfilePath_sypf = Server.MapPath("file/suiyin.jpg");
            if (!File.Exists(webFilePath))
            {
                try
                {
                    FileUpload1.SaveAs(webFilePath);
                    AddShuiYinWord(webFilePath, webFilePath_sy);
                    AddShuiYinPic(webFilePath, webfilePath_syp, webFilePath_sy);
                    MakeThumbnail(webFilePath, webFilePath_s, 130, 130, "Cut");
                    Label1.Text = "提示:文件  " + fileName + "  成功上传,并生成 " + fileName_s + " 缩略图,文件类型为：" + FileUpload1.PostedFile.ContentType + "，文件大小为：" + FileUpload1.PostedFile.ContentLength + "B";
                }
                catch (Exception ex)
                {
                    Label1.Text = "提示;文件上传失败,失败原因:" + ex.Message;
                }
            }
            else
            {
                Label1.Text = "提示：文件已经存在，请重新上传~！";
            }
        }
        else
        {
            Label1.Text = "提示：文件类型不符";
        }
    }
    /// <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":
                break;
            case "W":
                toheight = originalImage.Height * width / originalImage.Width;
                break;
            case "H":
                towidth = originalImage.Width * height / originalImage.Height;
                break;
            case "Cut":
                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.Width - ow) / 2;
                }
                break;
            default:
                break;
        }
        System.Drawing.Image bitmap = new System.Drawing.Bitmap(towidth, toheight);
        System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(bitmap);
        g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;
        g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
        g.Clear(System.Drawing.Color.Transparent);
        g.DrawImage(originalImage, new System.Drawing.Rectangle(0, 0, towidth, toheight), new System.Drawing.Rectangle(x, y, ow, oh), System.Drawing.GraphicsUnit.Pixel);
        try
        {
            bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Jpeg);
        }
        catch (Exception e)
        {
            throw e;
        }
        finally
        {
            originalImage.Dispose();
            bitmap.Dispose();
            g.Dispose();
        }
    }
    /// <summary>
    /// 在图片上增加文字水印
    /// </summary>
    /// <param name="Path">原服务器图片路径</param>
    /// <param name="Path_sy">生成的带文字水印的图片路径</param>
    protected void AddShuiYinWord(string Path, string Path_sy)
    {
        string addText = "我爱李婷婷";
        System.Drawing.Image image = System.Drawing.Image.FromFile(Path);
        System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(image);
        g.DrawImage(image, 0, 0, image.Width, image.Height);
        System.Drawing.Font f = new System.Drawing.Font("Verdana", 16);
        System.Drawing.Brush b = new System.Drawing.SolidBrush(System.Drawing.Color.Blue);
        g.DrawString(addText, f, b, 15, 15);
        g.Dispose();
        image.Save(Path_sy);
        image.Dispose();
    }
    /// <summary>
    /// 在图片上生成图片水印
    /// </summary>
    /// <param name="Path">原服务器上图片路径</param>
    /// <param name="Path_syp">生成的带图片水印的图片路径</param>
    /// <param name="Path_sypf">水印图片路径</param>
    protected void AddShuiYinPic(string Path, string Path_syp, string Path_sypf)
    {
        System.Drawing.Image image = System.Drawing.Image.FromFile(Path);
        System.Drawing.Image copyImage = System.Drawing.Image.FromFile(Path_sypf);
        System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(image);
        g.DrawImage(copyImage, new System.Drawing.Rectangle(image.Width - copyImage.Width, image.Height - copyImage.Height, copyImage.Width, copyImage.Height), 0, 0, copyImage.Width, copyImage.Height, System.Drawing.GraphicsUnit.Pixel);
        g.Dispose();
        image.Save(Path_syp);
        image.Dispose();
    }