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
  1 /// <summary>
  2         /// 生成缩略图
  3         /// </summary>
  4         /// <param name="originalImagePath">源图路径（物理路径）</param>
  5         /// <param name="thumbnailPath">缩略图路径（物理路径）</param>
  6         /// <param name="width">缩略图宽度</param>
  7         /// <param name="height">缩略图高度</param> 
  8 
  9         public void CreateMinImage(string originalImagePath, string thumbnailPath, int width, int height)
 10         {
 11             System.Drawing.Image originalImage = System.Drawing.Image.FromFile(HttpContext.Current.Server.MapPath(originalImagePath));
 12 
 13             int towidth = width;
 14             int toheight = height;
 15 
 16             int ow = originalImage.Width;
 17             int oh = originalImage.Height;
 18 
 19             //新建一个bmp图片
 20             System.Drawing.Image bitmap = new System.Drawing.Bitmap(towidth, toheight);
 21 
 22             //新建一个画板
 23             System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(bitmap);
 24 
 25 
 26             //设置高质量插值法
 27             g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;
 28 
 29             //设置高质量,低速度呈现平滑程度
 30             g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
 31 
 32             //清空画布并以透明背景色填充
 33             g.Clear(System.Drawing.Color.Transparent);
 34 
 35             //在指定位置并且按指定大小绘制原图片的指定部分
 36             g.DrawImage(originalImage, new System.Drawing.Rectangle(0, 0, towidth, toheight));
 37 
 38             try
 39             {
 40                 //以jpg格式保存缩略图
 41                 string FileExt = Path.GetFileNameWithoutExtension(originalImagePath);
 42 //这里报错               bitmap.Save(HttpContext.Current.Server.MapPath(thumbnailPath) + FileExt + ".jpg", System.Drawing.Imaging.ImageFormat.Jpeg);
 43             }
 44             catch (System.Exception e)
 45             {
 46                 throw e;
 47             }
 48             finally
 49             {
 50                 originalImage.Dispose();
 51                 bitmap.Dispose();
 52                 g.Dispose();
 53             }
 54 
 55         }
 56 
 57 //修改后的代码
 58 public void CreateMinImageAndDel(string originalImagePath, string thumbnailPath, int width, int height)
 59         {
 60             Graphics draw = null;
 61             string FileExt = "";
 62 
 63             System.Drawing.Image originalImage = System.Drawing.Image.FromFile(HttpContext.Current.Server.MapPath(originalImagePath));
 64 
 65             int towidth = width;
 66             int toheight = height;
 67 
 68             int ow = originalImage.Width;
 69             int oh = originalImage.Height;
 70 
 71             //新建一个bmp图片
 72             System.Drawing.Image bitmap = new System.Drawing.Bitmap(towidth, toheight);
 73             System.Drawing.Image bitmap2 = new System.Drawing.Bitmap(towidth, toheight);
 74             //新建一个画板
 75             System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(bitmap);
 76 
 77 
 78             //设置高质量插值法
 79             g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;
 80 
 81             //设置高质量,低速度呈现平滑程度
 82             g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
 83 
 84             //清空画布并以透明背景色填充
 85             g.Clear(System.Drawing.Color.Transparent);
 86 
 87             //在指定位置并且按指定大小绘制原图片的指定部分
 88             g.DrawImage(originalImage, new System.Drawing.Rectangle(0, 0, towidth, toheight));
 89 
 90             try
 91             {
 92                 //以jpg格式保存缩略图
 93                 FileExt = Path.GetFileNameWithoutExtension(originalImagePath);
 94 　　　　　　　　　　//用新建立的image对象拷贝bitmap对象 让g对象可以释放资源
 95                 draw = Graphics.FromImage(bitmap2);
 96                 draw.DrawImage(bitmap, 0, 0);
 97 
 98             }
 99             catch (System.Exception e)
100             {
101                 throw e;
102             }
103             finally
104             {
105                 originalImage.Dispose();
106                 bitmap.Dispose();
107                 g.Dispose();
108 　　　　　　　　　　//保存调整在这里即可
109                 bitmap2.Save(HttpContext.Current.Server.MapPath(thumbnailPath) + FileExt + ".jpg", System.Drawing.Imaging.ImageFormat.Jpeg);
110             }
111         }