如何使用(在Delphi中)创建文件(或文件集)的数据库格式？

然后你可以从它所谓的“签名”中猜出文件格式.

这主要是第一个字符内容,它能够识别文件格式.

您在此very nice Gary Kessler’s网站上有一个更新列表.

例如,这是服务器端的how our framework identify the MIME format from the file content：

function GetMimeContentType(Content: Pointer; Len: integer;
  const FileName: TFileName=''): RawUTF8;
begin // see http://www.garykessler.net/library/file_sigs.html for magic numbers
  result := '';
  if (Content<>nil) and (Len>4) then
    case PCardinal(Content)^ of
    $04034B50: Result := 'application/zip'; // 50 4B 03 04
    $46445025: Result := 'application/pdf'; //  25 50 44 46 2D 31 2E
    $21726152: Result := 'application/x-rar-compressed'; // 52 61 72 21 1A 07 00
    $AFBC7A37: Result := 'application/x-7z-compressed';  // 37 7A BC AF 27 1C
    $75B22630: Result := 'audio/x-ms-wma'; // 30 26 B2 75 8E 66
    $9AC6CDD7: Result := 'video/x-ms-wmv'; // D7 CD C6 9A 00 00
    $474E5089: Result := 'image/png'; // 89 50 4E 47 0D 0A 1A 0A
    $38464947: Result := 'image/gif'; // 47 49 46 38
    $002A4949,$2A004D4D,$2B004D4D:
      Result := 'image/tiff'; // 49 49 2A 00 or 4D 4D 00 2A or 4D 4D 00 2B
    $E011CFD0: // Microsoft Office applications D0 CF 11 E0 = DOCFILE
      if Len>600 then
      case PWordArray(Content)^[256] of // at offset 512
        $A5EC: Result := 'application/msword'; // EC A5 C1 00
        $FFFD: // FD FF FF
          case PByteArray(Content)^[516] of
            $0E,$1C,$43: Result := 'application/vnd.ms-powerpoint';
            $10,$1F,$20,$22,$23,$28,$29: Result := 'application/vnd.ms-excel';
          end;
      end;
    else
      case PCardinal(Content)^ and $00ffffff of
        $685A42: Result := 'application/bzip2'; // 42 5A 68
        $088B1F: Result := 'application/gzip'; // 1F 8B 08
        $492049: Result := 'image/tiff'; // 49 20 49
        $FFD8FF: Result := 'image/jpeg'; // FF D8 FF DB/E0/E1/E2/E3/E8
        else
          case PWord(Content)^ of
            $4D42: Result := 'image/bmp'; // 42 4D
          end;
      end;
    end;
  if (Result='') and (FileName<>'') then begin
    case GetFileNameExtIndex(FileName,'png,gif,tiff,tif,jpg,jpeg,bmp,doc,docx') of
      0:   Result := 'image/png';
      1:   Result := 'image/gif';
      2,3: Result := 'image/tiff';
      4,5: Result := 'image/jpeg';
      6:   Result := 'image/bmp';
      7,8: Result := 'application/msword';
      else begin
        Result := RawUTF8(ExtractFileExt(FileName));
        if Result<>'' then begin
          Result[1] := '/';
          Result := 'application'+LowerCase(Result);
        end;
      end;
    end;
  end;
  if Result='' then
    Result := 'application/octet-stream';
end;

您可以使用GAry Kessler列表中的类似功能.