如何实现将用户上传的文件生成缩略图!

具体给个例子就清楚啦。。
如下：

System.Web.HttpPostedFile UpFile = UpMhtFile.PostedFile;<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />               System.IO.Stream StreamObject = UpFile.InputStream;               System.IO.FileStream myStream = new System.IO.FileStream(UpFile.FileName,System.IO.FileMode.Open,System.IO.FileAccess.Read);                             System.Drawing.Image.GetThumbnailImageAbort myCallback =                    new System.Drawing.Image.GetThumbnailImageAbort(ThumbnailCallback);                 System.Drawing.Image img1 = System.Drawing.Image.FromStream(StreamObject);                          System.Drawing.Image timg = img1.GetThumbnailImage(100,100,myCallback,System.IntPtr.Zero);               timg.Save(Response.OutputStream,System.Drawing.Imaging.ImageFormat.Jpeg);

上例中UpMhtFile是一个upfile WebControl，上述情况将上传的图片转换成流,然后生成缩略图后直接保存在输出流中,一般用于从数据库中读出流后生成图片浏览。