c#真正判斷檔案類型

標籤：

//真正判斷檔案類型的關鍵函數    public static bool IsAllowedExtension2(FileUpload hifile)    {        if (hifile != null)        {            System.IO.FileStream fs = new System.IO.FileStream(hifile.PostedFile.FileName, System.IO.FileMode.Open, System.IO.FileAccess.Read);            System.IO.BinaryReader r = new System.IO.BinaryReader(fs);            string fileclass = "";            byte buffer;            try            {                buffer = r.ReadByte();                fileclass = buffer.ToString();                buffer = r.ReadByte();                fileclass += buffer.ToString();            }            catch            {            }            r.Close();            fs.Close();            if (fileclass == "255216" || fileclass == "7173")//說明255216是jpg;7173是gif;6677是BMP,13780是PNG;7790是exe,8297是rar            {                return true;            }            else            {                return false;            }        }        else { return false; }    }  

　　

c#真正判斷檔案類型