c#多图片上传并生成缩略图的实例代码

                 {
                     SmallImg(postFile.InputStream, postFile.FileName);
                 }
                 else
                 {
                     msg = "只能上传JGP、PNG类型的图片，请检查文件格式是否正确";
                     Page.ClientScript.RegisterStartupScript(GetType(), "", "ValidImage(" + uploadFileID + "," + msg + ")", true);//将提示信息发送到客户端
                     File.Delete(savePath);  //如果不是图片就删除
                 }
             }
         }
     }

  #region 验证上传文件的格式
     /// <summary>
     /// 验证上传文件是否是图片
     /// </summary>
     /// <param name="FilePath">文件的保存路径</param>
     /// <returns></returns>
     private bool IsImg(string FilePath)
     {
         using (FileStream fs = new FileStream(FilePath, FileMode.Open, FileAccess.Read))
         {
             bool result = false;
             BinaryReader br = new BinaryReader(fs, System.Text.Encoding.UTF8);
             string strImg = "";
             byte buffer;
             try
             {
                 buffer = br.ReadByte();
                 strImg = buffer.ToString();
                 buffer = br.ReadByte();