上传图片，生成缩略图和删除图片的示例

简单的上传文件的webForm实例：

 protected void Button1_Click(object sender, EventArgs e)        {            if (FileUpload1.HasFile)            {                string fileContentType = FileUpload1.PostedFile.ContentType;                if (fileContentType == "image/jpeg" || fileContentType == "image/gif" || fileContentType == "image/jpg")                {                    string name = FileUpload1.PostedFile.FileName;                  // 客户端文件路径                    FileInfo file = new FileInfo(name);                    string fileName = file.Name;                                    // 文件名称                    string fileName_s = "x_" + file.Name;                           // 缩略图文件名称                    string webFilePath = Server.MapPath("ImgUpload/" + fileName);        // 服务器端文件路径                    string webFilePath_s = Server.MapPath("ImgUpload/" + fileName_s);　　// 服务器端缩略图路径                    if (!File.Exists(webFilePath))                    {                        try                        {                            FileUpload1.SaveAs(webFilePath);                                // 使用 SaveAs 方法保存文件                            MakeThumbnail(webFilePath, webFilePath_s, 130, 130);     // 生成缩略图方法                            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";                            Image1.ImageUrl = webFilePath;                            Image2.ImageUrl = webFilePath_s;                        }                        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";                    }                }                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)        {            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;            //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();            }        }        protected void Button2_Click(object sender, EventArgs e)        {            string path = "C:\\Users\\J\\Desktop\\WebApplication1\\WebApplication1\\ImgUpload\\0.jpg";            string path2 = "C:\\Users\\J\\Desktop\\WebApplication1\\WebApplication1\\ImgUpload\\x_0.jpg";            if (File.Exists(path))                try                {                    File.Delete(path);                    File.Delete(path2);                }                catch                {                    Label1.Text = "fail";                    Page.ClientScript.RegisterStartupScript(Page.GetType(), "message", "script language = 'javascript' defer>alert('删除失败');</script>");                }            else {                Label1.Text = "no file";            }        }    }