通过字节识别文件
http://blog.sina.com.cn/s/blog_62b832910100vmbq.html
通过相关文件格式，获取文件实际类型
YII的代码
01 | class FileTools{ |
02 | public static function getFileType($file,&$fileType,&$mime){ |
03 | $bin = substr($file,0,2); |
04 | $strInfo = @unpack("C2chars", $bin); |
05 | $typeCode = intval($strInfo['chars1'].$strInfo['chars2']); |
06 | $fileType = ''; |
07 | switch ($typeCode) |
08 | { |
09 | case 7790: |
10 | $fileType = 'exe'; |
11 | return false; |
12 | break; |
13 | case 7784: |
14 | $fileType = 'midi'; |
15 | return false; |
16 | break; |
17 | case 8297: |
18 | $fileType = 'rar'; |
19 | return false; |
20 | break; |
21 | case 255216: |
22 | $fileType = 'jpg'; |
23 | $mime = 'image/jpeg'; |
24 | return true; |
25 | break; |
26 | case 7173: |
27 | $fileType = 'gif'; |
28 | $mime = 'image/gif'; |
29 | return true; |
30 | break; |
31 | case 6677: |
32 | $fileType = 'bmp'; |
33 | $mime = 'image/bmp'; |
34 | return true; |
35 | break; |
36 | case 13780: |
37 | $fileType = 'png'; |
38 | $mime = 'image/png'; |
39 | return true; |
40 | break; |
41 | default: |
42 | return false; |
43 | break; |
44 | } |
45 | return false; |
46 | } |
47 | public static function getMimeType($file,$magicFile=null,$checkExtension=true) |
48 | { |
49 | if(function_exists('finfo_open')) |
50 | { |
51 | $options=defined('FILEINFO_MIME_TYPE') ? FILEINFO_MIME_TYPE : FILEINFO_MIME; |
52 | $info=$magicFile===null ? finfo_open($options) : finfo_open($options,$magicFile); |
53 |
54 | if($info && ($result=finfo_file($info,$file))!==false) |
55 | return $result; |
56 | } |
57 |
58 | if(function_exists('mime_content_type') && ($result=mime_content_type($file))!==false) |
59 | return $result; |
60 | return $checkExtension ? self::getMimeTypeByExtension($file) : null; |
61 | } |
62 | /** |
63 | * Determines the MIME type based on the extension name of the specified file. |
64 | * This method will use a local map between extension name and MIME type. |
65 | * @param string $file the file name. |
66 | * @param string $magicFile the path of the file that contains all available MIME type information. |
67 | * If this is not set, the default 'system.utils.mimeTypes' file will be used. |
68 | * This parameter has been available since version 1.1.3. |
69 | * @return string the MIME type. Null is returned if the MIME type cannot be determined. |
70 | */ |
71 | public static function getMimeTypeByExtension($file,$magicFile=null) |
72 | { |
73 | static $extensions; |
74 | if($extensions===null) |
75 | $extensions=$magicFile===null ? require('mimeTypes.php') : $magicFile; |
76 | if(($ext=pathinfo($file, PATHINFO_EXTENSION))!=='') |
77 | { |
78 | $ext=strtolower($ext); |
79 | if(isset($extensions[$ext])) |
80 | return $extensions[$ext]; |
81 | } |
82 | return null; |
83 | } |
84 | } |