在ASP.NET中实现图片上传，并按比例生成缩略图

private void btnUploadPicture_Click(object sender, System.EventArgs e)
{
         //检查上传文件的格式是否有效
         if(this.UploadFile.PostedFile.ContentType.ToLower().IndexOf("image") < 0)
         {
          Response.Write("上传图片格式无效！");
          return;
         }

         //生成原图
         Byte[] oFileByte = new byte[this.UploadFile.PostedFile.ContentLength];
         System.IO.Stream oStream = this.UploadFile.PostedFile.InputStream;
         System.Drawing.Image oImage = System.Drawing.Image.FromStream(oStream);

         int oWidth = oImage.Width; //原图宽度
         int oHeight = oImage.Height; //原图高度
         int tWidth = 100; //设置缩略图初始宽度
         int tHeight = 100; //设置缩略图初始高度

         //按比例计算出缩略图的宽度和高度
         if(oWidth >= oHeight)
         {
          tHeight = (int)Math.Floor(Convert.ToDouble(oHeight) * (Convert.ToDouble(tWidth) / Convert.ToDouble(oWidth)));
         }
         else
         {
          tWidth = (int)Math.Floor(Convert.ToDouble(oWidth) * (Convert.ToDouble(tHeight) / Convert.ToDouble(oHeight)));
         }

         //生成缩略原图
         Bitmap tImage = new Bitmap(tWidth,tHeight);
         Graphics g = Graphics.FromImage(tImage);
         g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High; //设置高质量插值法
         g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;//设置高质量,低速度呈现平滑程度
         g.Clear(Color.Transparent); //清空画布并以透明背景色填充
         g.DrawImage(oImage,new Rectangle(0,0,tWidth,tHeight),new Rectangle(0,0,oWidth,oHeight),GraphicsUnit.Pixel);

         string oFullName = Server.MapPath(".") + "/" + "o" + DateTime.Now.ToShortDateString().Replace("-","") + DateTime.Now.Hour.ToString() + DateTime.Now.Minute.ToString() + DateTime.Now.Second.ToString() + DateTime.Now.Millisecond.ToString() + ".jpg"; //保存原图的物理路径
         string tFullName = Server.MapPath(".") + "/" + "t" + DateTime.Now.ToShortDateString().Replace("-","") + DateTime.Now.Hour.ToString() + DateTime.Now.Minute.ToString() + DateTime.Now.Second.ToString() + DateTime.Now.Millisecond.ToString() + ".jpg"; //保存缩略图的物理路径

         try
         {
          //以JPG格式保存图片
          oImage.Save(oFullName,System.Drawing.Imaging.ImageFormat.Jpeg);
          tImage.Save(tFullName,System.Drawing.Imaging.ImageFormat.Jpeg);
         }
         catch(Exception ex)
         {
          throw ex;
         }
         finally
         {
          //释放资源
          oImage.Dispose();
          g.Dispose();
          tImage.Dispose();
         }
}