//strImgFilePath 图片文件名
string GetImageFormat(string strImgFilePath)
{
string strImgFormat = "";
System.Drawing.Image imgSrc = System.Drawing.Image.FromFile(strImgFilePath);
if (imgSrc.RawFormat.Equals(System.Drawing.Imaging.ImageFormat.Jpeg))
strImgFormat = "jpeg";
else if (imgSrc.RawFormat.Equals(System.Drawing.Imaging.ImageFormat.Gif))
strImgFormat = "gif";
else if (imgSrc.RawFormat.Equals(System.Drawing.Imaging.ImageFormat.Bmp))
strImgFormat = "bmp";
else if (imgSrc.RawFormat.Equals(System.Drawing.Imaging.ImageFormat.Png))
strImgFormat = "png";
else if (imgSrc.RawFormat.Equals(System.Drawing.Imaging.ImageFormat.Tiff))
strImgFormat = "tiff";
else if (imgSrc.RawFormat.Equals(System.Drawing.Imaging.ImageFormat.Icon))
strImgFormat = "icon";
else if (imgSrc.RawFormat.Equals(System.Drawing.Imaging.ImageFormat.Wmf))
strImgFormat = "wmf";
//可以再添加....
return strImgFormat;
}