判断文件真实后缀

#region 检测上传真实类型与后缀名是否匹配,是否在允许列表中,允许则上传返回上传路径
        public bool IsAllowedExtension(HttpPostedFile hifile,out string upfilepath)
        {
            bool ret = false;
            upfilepath = string.Empty;
            string UFileName = hifile.FileName.Trim();//获取文件名
            string WebPath = HttpContext.Current.Request.ApplicationPath + "UpLoadFile/FILE/" + System.DateTime.Today.Year.ToString() + "/" + System.DateTime.Today.Month.ToString() + "/"; ;//上传到指定路径
            string Exten = Path.GetExtension(hifile.FileName).ToUpper();//获取文件的扩展名
            int FileLength = hifile.ContentLength;//文件大小
            string FileType = hifile.ContentType.ToUpper();//获取文件的类型

            //int   fileLengh   =   hifile.ContentLength;
            //byte[] fileByte = new byte[fileLengh];    
            //Stream   fileStream   =   hifile.InputStream;//建立文件流对象     
            ////fileStream.Read(fileByte, 0, fileLengh);
            //fileStream.Read(fileByte, 0, 1);
            //fileStream.Read(fileByte, 1, 1);
            //string fileCode = fileByte[0].ToString() + fileByte[1].ToString();

            string fileCode = hifile.InputStream.ReadByte().ToString() + hifile.InputStream.ReadByte().ToString();//文件真实类型代码
            if (fileCode != GetFileType(Exten))//判断后缀名返回的代码是否与文件真实类型匹配
            {
                return false;
            }

            String[] fileType = { "255216", "7173", "6677", "13780", "8297", "8075", "208207" };//允许上传列表
            for (int i = 0; i < fileType.Length; i++)
            {
                if (fileCode == fileType[i])
                {
                    ret = true;
                    break;
                }
            }
            if (ret == false) return ret;

            
            if (!Directory.Exists(WebPath))
            {
                Directory.CreateDirectory(WebPath);
            }
            string UploadFileName = DateTime.Now.Year.ToString() + DateTime.Now.Month.ToString() + DateTime.Now.Day.ToString() + DateTime.Now.Hour.ToString() + DateTime.Now.Minute.ToString() + DateTime.Now.Millisecond.ToString() + Exten;
            upfilepath = WebPath + UploadFileName;
            hifile.SaveAs(upfilepath);

            //System.IO.FileStream fs = new System.IO.FileStream(upfilepath, 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
            //{
            //    return false;
            //}
            //r.Close();
            //fs.Close();

            //if (fileclass != GetFileType(Exten))
            //{
            //    File.Delete(WebPath + UploadFileName);
            //    ret = false;
            //}
            //else
            //{
            //    upfilepath = WebPath + UploadFileName;
            //    ret = true;
            //}

            return ret;
        }


        /*文件扩展名说明
             *7173        gif 
             *255216      jpg
             *13780       png
             *6677        bmp
             *239187      txt,aspx,asp,sql
             *208207      xls.doc.ppt
             *6063        xml
             *6033        htm,html
             *4742        js
             *8075        xlsx,zip,pptx,mmap,zip
             *8297        rar   
             *01          accdb,mdb
             *7790        exe,dll           
             *5666        psd 
             *255254      rdp 
             *10056       bt种子 
             *64101       bat 
*/
        private string GetFileType(string fileExtenstion)
        {
            string code =string.Empty;
            switch (fileExtenstion)
            {
                case ".GIF":
                    code = "7173";
                    break;
                case ".JPG":
                    code = "255216";
                    break;
                case ".XLS":
                    code = "208207";
                    break;
                default:
                    break;
            }
            return code;
        }
        #endregion