function checkFileType($fileName){

　　$file = fopen($fileName, "rb");

　　$bin = fread($file, 2); //只读2字节

　　fclose($file);

　　$strInfo = @unpack("C2chars", $bin);// C为无符号整数，网上搜到的都是c，为有符号整数，这样会产生负数判断不正常

　　$typeCode = intval($strInfo['chars1'].$strInfo['chars2']);

　　$fileType = '';

　　if($typeCode == 255216 /*jpg*/ || $typeCode == 7173 /*gif*/ || $typeCode == 13780 /*png*/) {

　　　　return true;

　　}else{

　　　　return false;

　　}

}

 

File Header文件头，通过检查文件头来判断文件类型

由这些文件头即使文件后缀被乱改也可以通过查看二进制文件查出文件的匹配格式,当然这就是一些播放器识别文件的方法

1、从Ultra－edit-32中提取出来的

JPEG (jpg)，文件头：FFD8FF 

PNG (png)，文件头：89504E47 

GIF (gif)，文件头：47494638 

TIFF (tif)，文件头：49492A00 

Windows Bitmap (bmp)，文件头：424D 

CAD (dwg)，文件头：41433130 

Adobe Photoshop (psd)，文件头：38425053 

Rich Text Format (rtf)，文件头：7B5C727466 

XML (xml)，文件头：3C3F786D6C 

HTML (html)，文件头：68746D6C3E 

Email [thorough only] (eml)，文件头：44656C69766572792D646174653A 

Outlook Express (dbx)，文件头：CFAD12FEC5FD746F 

Outlook (pst)，文件头：2142444E 

MS Word/Excel (xls.or.doc)，文件头：D0CF11E0 

MS Access (mdb)，文件头：5374616E64617264204A 

WordPerfect (wpd)，文件头：FF575043 

Postscript (eps.or.ps)，文件头：252150532D41646F6265 

Adobe Acrobat (pdf)，文件头：255044462D312E 

Quicken (qdf)，文件头：AC9EBD8F 

Windows Password (pwl)，文件头：E3828596 

ZIP Archive (zip)，文件头：504B0304 

RAR Archive (rar)，文件头：52617221 

Wave (wav)，文件头：57415645 

AVI (avi)，文件头：41564920 

Real Audio (ram)，文件头：2E7261FD 

Real Media (rm)，文件头：2E524D46 

MPEG (mpg)，文件头：000001BA 

MPEG (mpg)，文件头：000001B3 

Quicktime (mov)，文件头：6D6F6F76 

Windows Media (asf)，文件头：3026B2758E66CF11 

MIDI (mid)，文件头：4D546864 

二、从winhex中取出的文件头列表

File                             Type                          ExtensionsHeader

JPEG                             jpg;jpeg                      0xFFD8FF

PNG                              png                           0x89504E470D0A1A0A

GIF                              gif                           GIF8

TIFF                             tif;tiff                      0x49492A00

TIFF                             tif;tiff                      0x4D4D002A

Bit   map                         bmp                           BM

AOL ART                          art                           0x4A47040E000000

AOL ART                          art                           0x4A47030E000000

PC Paintbrush                    pcx                           0x0A050108

Graphics Metafile                wmf                           0xD7CDC69A

Graphics Metafile                wmf                           0x01000900

Graphics Metafile                wmf                           0x02000900

Enhanced Metafile                emf                           0x0100000058000000

Corel Draw                       cdr                           CDR

CAD                              dwg                           0x41433130

Adobe Photoshop                  psd                           8BPS

Rich Text Format                 rtf                           rtf

XML                              xml                              

HTML                 html;htm;php;php3;php4;phtml;shtml         type

Email                            eml                            Delivery-date:

Outlook Express                  dbx                            0xCFAD12FE

Outlookpst!BDN

MS Office/OLE2     doc;xls;dot;ppt;xla;ppa;pps;pot;msi;sdw;db   0xD0CF11E0A1B11AE1

MS Access                 mdb;mda;mde;mdt                       Standard J

WordPerfect                      wpd                           0xFF575043

OpenOffice Writer                sxw                           writer

OpenOffice Calc                  sxc                           calc

OpenOffice Math                  sxm                           math

OpenOffice Impress               sxi                           impress

OpenOffice Draw                  sxd                           draw

Adobe FrameMaker                 fm                            <MAKERFILE

PostScript                       eps.or.ps;ps;eps              %!PS-Adobe

Adobe Acrobat                    pdf                           %PDF-1.

Quicken                          qdf                           0xAC9EBD8F

QuickBooks Backup                qbb                           0x458600000600

Sage                             sly.or.srt.or.slt;sly;srt;slt      0x53520100

Sage Backup                      1                                  SAGEBACKUP

Lotus WordPro v9                 lwp                           0x576F726450726F

Lotus 123 v9                     123                           0x00001A00051004

Lotus 123 v5                     wk4                           0x00001A0002100400

Lotus 123 v3                     wk3                           0x00001A0000100400

Lotus 123 v1                     wk1                            0x2000604060

Windows Password                 pwl                            0xE3828596

ZIP Archive                      zip;jar                        0x504B0304

ZIP Archive (outdated)           zip                            0x504B3030

RAR Archive                      rar                            Rar!

GZ Archive                       gz;tgz                         0x1F8B08

BZIP Archive                     bz2                            BZh

ARJ Archive                      arj                            0x60EA

7－ZIP Archive                   7z                             7z集'

Wave                             wav                            WAVE

AVI                              avi                            AVI 

Real Audio                       ram;ra                         .ra?0

Real Media                       rm                             .RMF

MPEG                             mpg;mpeg                       0x000001BA

MPEG                             mpg;mpeg                       0x000001B3

Quicktime                        mov                            moov

Windows Media                    asf                            0x3026B2758E66CF11

MIDI                             mid                            MThd

Win32 Executable                 exe;dll;drv;vxd;sys;ocx;vbx    MZ

Win16 Executable                 exe;dll;drv;vxd;sys;ocx;vbx    MZ

ELF Executable                   elf;;                          0x7F454C4601010100