C#检测上传文件类型（真实检测，不通过后缀名）

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// <summary>

        /// C#检测真实文件类型函数

        /// </summary>

        /// <param name="hifile"></param>

        /// <returns></returns>

        publicstatic bool IsAllowedExtension(HttpPostedFile hifile)

        {

            boolret = false;

 

            //System.IO.FileStream fs = new System.IO.FileStream(hifile.FileName, System.IO.FileMode.Open, System.IO.FileAccess.Read);

            System.IO.BinaryReader r = newSystem.IO.BinaryReader(hifile.InputStream);

            //hifile.InputStream

            stringfileclass = "";

            bytebuffer;

            try

            {

                buffer = r.ReadByte();

                fileclass = buffer.ToString();

                buffer = r.ReadByte();

                fileclass += buffer.ToString();

            }

            catch

            {

                returnfalse;

            }

            r.Close();