验证图片的真实类型

代码如下：

 

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/// <summary> /// 验证图片的真实类型，并尝试保存图片 /// </summary> /// <param name="hifile">FileUpload 控件ID</param> /// <param name="savedPath">要保存图片的虚拟路径（虚拟路径不能包括扩展名，正确的写法比如"/video/2010/5/中国人"），如果上传失败，则保存的路径为空</param> /// <param name="errorMessage">如果上传失败，错误消息</param> /// <param name="allowFileEmpty">是否允许FileUpload没有文件，如果允许，则当FileUpload为空时，不显示错误信息</param> /// <param name="limitImgSize">是否限制图片的大小，true表示限制</param> /// <param name="imgSize_MB">如果限制图片的大小成立，即参数“limitImgSize”的值为True，则最大能允许的图片的兆数（MB）</param> /// <returns>验证结果,true表示成功，false表示失败</returns> public static bool ValidateImgExtensionAndSave(FileUpload hifile, ref string savedVirtualPath, out string errorMessage, bool allowFileEmpty, bool limitImgSize, double imgSize_MB) {     if (hifile != null && hifile.HasFile)     {         Stream streamInput = hifile.PostedFile.InputStream;           BinaryReader r = new BinaryReader(streamInput);         string fileclass = "";         byte buffer;         try         {             buffer = r.ReadByte();             fileclass = buffer.ToString();             buffer = r.ReadByte();             fileclass += buffer.ToString();             //r.Close();         }         catch (Exception)         {             r.Close();             streamInput.Close();             errorMessage = "读取文件流失败，请确定您文件的正确性！";             savedVirtualPath = string.Empty;             return false;         }         //说明255216是jpg;7173是gif;6677是BMP,13780是PNG;7790是exe,8297是rar         if (fileclass == "255216" || fileclass == "7173" || fileclass == "6677" || fileclass == "13780")         {             //成功             if (limitImgSize)             {                 //限制图片的大小                 double imgSize = (double)streamInput.Length / (1024 * 1024);                 if (imgSize > imgSize_MB)                 {                     errorMessage = "图片的大小最大不能超过" + imgSize_MB + "M";                     savedVirtualPath = string.Empty;                     streamInput.Close();                     return false;                 }             }             string imgExtension = string.Empty;             System.Drawing.Imaging.ImageFormat imgFormat;             switch (fileclass)             {                 case "255216":                     imgExtension = ".jpg";                     imgFormat = System.Drawing.Imaging.ImageFormat.Jpeg;                     break;                 case "7173":                     imgExtension = ".gif";                     imgFormat = System.Drawing.Imaging.ImageFormat.Gif;                     break;                 case "6677":                     imgExtension = ".bmp";                     imgFormat = System.Drawing.Imaging.ImageFormat.Bmp;                     break;                 case "13780":                     imgExtension = ".png";                     imgFormat = System.Drawing.Imaging.ImageFormat.Png;                     break;                 default:                     imgFormat = System.Drawing.Imaging.ImageFormat.Jpeg;                     break;             }             System.Drawing.Image img = System.Drawing.Image.FromStream(streamInput);             if (savedVirtualPath.LastIndexOf('/') == (savedVirtualPath.Length - 1))             {                 throw new Exception("没有文件名，正确的格式应该比如为：/目录名/.../myImg，其中\"myImg\"表示文件名！");             }             savedVirtualPath = savedVirtualPath + imgExtension;             string physicalImgPath = HttpContext.Current.Server.MapPath(savedVirtualPath);             string physicalImgDictionaryPath = physicalImgPath.Substring(0, physicalImgPath.LastIndexOf('\\'));             if (!Directory.Exists(physicalImgDictionaryPath))             {                 Directory.CreateDirectory(physicalImgDictionaryPath);             }             img.Save(HttpContext.Current.Server.MapPath(savedVirtualPath), imgFormat);             img.Dispose();             streamInput.Close();             errorMessage = string.Empty;             return true;         }         else         {             errorMessage = "图片格式不正确！";             savedVirtualPath = string.Empty;             return false;         }     }     else     {         savedVirtualPath = string.Empty;         if (allowFileEmpty)         {             //允许上传的文件为空             errorMessage = string.Empty;             return true;         }         else         {             //一定要有文件             errorMessage = "没有文件，或文件为空！";             return false;         }     } }

 转自：http://www.cnblogs.com/Music/archive/2010/08/26/ValidateImgExtensionAndSave.html