图片上传代码（C#）

//上传

protected void Button1_Click(object sender, EventArgs e)
        {
            if (FileUpload1.HasFile)
            {
                string fileContentType = FileUpload1.PostedFile.ContentType;
                if (fileContentType == "image/bmp" || fileContentType == "image/gif" || fileContentType == "image/pjpeg")
                {
                    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 fileName_sy = "text_" + file.Name;                         // 水印图文件名称（文字）
                    string fileName_syp = "water_" + file.Name;                       // 水印图文件名称（图片）
                    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
                    string webFilePath_sy = Server.MapPath("ImgUpload/" + fileName_sy);　// 服务器端带水印图路径(文字)
                    string webFilePath_syp = Server.MapPath("ImgUpload/" + fileName_syp);　// 服务器端带水印图路径(图片)
                    string webFilePath_sypf = Server.MapPath("test.png");　// 服务器端水印图路径(图片)

if (!File.Exists(webFilePath))
                    {
                        try
                        {
                            FileUpload1.SaveAs(webFilePath);                                // 使用 SaveAs 方法保存文件
                            AddWater(webFilePath, webFilePath_sy);
                            AddWaterPic(webFilePath, webFilePath_syp, webFilePath_sypf);
                            MakeThumbnail(webFilePath, webFilePath_s, 130, 130, "Cut");     // 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";
                        }
                        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，请重命名后上传";
                    }
                }
                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"://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();
            }
        }

/**/
        /// <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 AddWater(string Path, string Path_sy)
        {
            string addText = "中国";
            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", 60);
            System.Drawing.Brush b = new System.Drawing.SolidBrush(System.Drawing.Color.Green);

g.DrawString(addText, f, b, 35, 35);
            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 AddWaterPic(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();
        }