GDI+ 发生一般性错误解决办法

错误的代码g对象继续占用 未释放资源 如果路径不一样 没问题 相同路径 获取图片进行

缩略会造成GDI错误

 /// <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> 

         public void CreateMinImage(string originalImagePath, string thumbnailPath, int width, int height)
         {
             System.Drawing.Image originalImage = System.Drawing.Image.FromFile(HttpContext.Current.Server.MapPath(originalImagePath));

             int towidth = width;
             int toheight = height;

             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(, , towidth, toheight));

             try
             {
                 //以jpg格式保存缩略图
                 string FileExt = Path.GetFileNameWithoutExtension(originalImagePath);
 //这里报错               bitmap.Save(HttpContext.Current.Server.MapPath(thumbnailPath) + FileExt + ".jpg", System.Drawing.Imaging.ImageFormat.Jpeg);
             }
             catch (System.Exception e)
             {
                 throw e;
             }
             finally
             {
                 originalImage.Dispose();
                 bitmap.Dispose();
                 g.Dispose();
             }

         }

 //修改后的代码
 public void CreateMinImageAndDel(string originalImagePath, string thumbnailPath, int width, int height)
         {
             Graphics draw = null;
             string FileExt = "";

             System.Drawing.Image originalImage = System.Drawing.Image.FromFile(HttpContext.Current.Server.MapPath(originalImagePath));

             int towidth = width;
             int toheight = height;

             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);
             System.Drawing.Image bitmap2 = 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(, , towidth, toheight));

             try
             {
                 //以jpg格式保存缩略图
                 FileExt = Path.GetFileNameWithoutExtension(originalImagePath);
 　　　　　　　　　　//用新建立的image对象拷贝bitmap对象 让g对象可以释放资源
                 draw = Graphics.FromImage(bitmap2);
                 draw.DrawImage(bitmap, , );

             }
             catch (System.Exception e)
             {
                 throw e;
             }
             finally
             {
                 originalImage.Dispose();
                 bitmap.Dispose();
                 g.Dispose();
 　　　　　　　　　　//保存调整在这里即可
                 bitmap2.Save(HttpContext.Current.Server.MapPath(thumbnailPath) + FileExt + ".jpg", System.Drawing.Imaging.ImageFormat.Jpeg);
             }
         }