PHP获得文件的mime type类型

<?php
/**
 * 获得文件的mime type类型
 * @author xiaobing.meng
 *
 */
class MimeTypes {
    public static $mime_types = array (
            'apk' => 'application/vnd.android.package-archive',
            '3gp' => 'video/3gpp', 
            'ai' => 'application/postscript', 
            'aif' => 'audio/x-aiff', 
            'aifc' => 'audio/x-aiff', 
            'aiff' => 'audio/x-aiff', 
            'asc' => 'text/plain', 
            'atom' => 'application/atom+xml', 
            'au' => 'audio/basic', 
            'avi' => 'video/x-msvideo', 
            'bcpio' => 'application/x-bcpio', 
            'bin' => 'application/octet-stream', 
            'bmp' => 'image/bmp', 
            'cdf' => 'application/x-netcdf', 
            'cgm' => 'image/cgm', 
            'class' => 'application/octet-stream', 
            'cpio' => 'application/x-cpio', 
            'cpt' => 'application/mac-compactpro', 
            'csh' => 'application/x-csh', 
            'css' => 'text/css', 
            'dcr' => 'application/x-director', 
            'dif' => 'video/x-dv', 
            'dir' => 'application/x-director', 
            'djv' => 'image/vnd.djvu', 
            'djvu' => 'image/vnd.djvu', 
            'dll' => 'application/octet-stream', 
            'dmg' => 'application/octet-stream', 
            'dms' => 'application/octet-stream', 
            'doc' => 'application/msword', 
            'dtd' => 'application/xml-dtd', 
            'dv' => 'video/x-dv', 
            'dvi' => 'application/x-dvi', 
            'dxr' => 'application/x-director', 
            'eps' => 'application/postscript', 
            'etx' => 'text/x-setext', 
            'exe' => 'application/octet-stream', 
            'ez' => 'application/andrew-inset', 
            'flv' => 'video/x-flv', 
            'gif' => 'image/gif', 
            'gram' => 'application/srgs', 
            'grxml' => 'application/srgs+xml', 
            'gtar' => 'application/x-gtar', 
            'gz' => 'application/x-gzip', 
            'hdf' => 'application/x-hdf', 
            'hqx' => 'application/mac-binhex40', 
            'htm' => 'text/html', 
            'html' => 'text/html', 
            'ice' => 'x-conference/x-cooltalk', 
            'ico' => 'image/x-icon', 
            'ics' => 'text/calendar', 
            'ief' => 'image/ief', 
            'ifb' => 'text/calendar', 
            'iges' => 'model/iges', 
            'igs' => 'model/iges', 
            'jnlp' => 'application/x-java-jnlp-file', 
            'jp2' => 'image/jp2', 
            'jpe' => 'image/jpeg', 
            'jpeg' => 'image/jpeg', 
            'jpg' => 'image/jpeg', 
            'js' => 'application/x-javascript', 
            'kar' => 'audio/midi', 
            'latex' => 'application/x-latex', 
            'lha' => 'application/octet-stream', 
            'lzh' => 'application/octet-stream', 
            'm3u' => 'audio/x-mpegurl', 
            'm4a' => 'audio/mp4a-latm', 
            'm4p' => 'audio/mp4a-latm', 
            'm4u' => 'video/vnd.mpegurl', 
            'm4v' => 'video/x-m4v', 
            'mac' => 'image/x-macpaint', 
            'man' => 'application/x-troff-man', 
            'mathml' => 'application/mathml+xml', 
            'me' => 'application/x-troff-me', 
            'mesh' => 'model/mesh', 
            'mid' => 'audio/midi', 
            'midi' => 'audio/midi', 
            'mif' => 'application/vnd.mif', 
            'mov' => 'video/quicktime', 
            'movie' => 'video/x-sgi-movie', 
            'mp2' => 'audio/mpeg', 
            'mp3' => 'audio/mpeg', 
            'mp4' => 'video/mp4', 
            'mpe' => 'video/mpeg', 
            'mpeg' => 'video/mpeg', 
            'mpg' => 'video/mpeg', 
            'mpga' => 'audio/mpeg', 
            'ms' => 'application/x-troff-ms', 
            'msh' => 'model/mesh', 
            'mxu' => 'video/vnd.mpegurl', 
            'nc' => 'application/x-netcdf', 
            'oda' => 'application/oda', 
            'ogg' => 'application/ogg', 
            'ogv' => 'video/ogv', 
            'pbm' => 'image/x-portable-bitmap', 
            'pct' => 'image/pict', 
            'pdb' => 'chemical/x-pdb', 
            'pdf' => 'application/pdf', 
            'pgm' => 'image/x-portable-graymap', 
            'pgn' => 'application/x-chess-pgn', 
            'pic' => 'image/pict', 
            'pict' => 'image/pict', 
            'png' => 'image/png', 
            'pnm' => 'image/x-portable-anymap', 
            'pnt' => 'image/x-macpaint', 
            'pntg' => 'image/x-macpaint', 
            'ppm' => 'image/x-portable-pixmap', 
            'ppt' => 'application/vnd.ms-powerpoint', 
            'ps' => 'application/postscript', 
            'qt' => 'video/quicktime', 
            'qti' => 'image/x-quicktime', 
            'qtif' => 'image/x-quicktime', 
            'ra' => 'audio/x-pn-realaudio', 
            'ram' => 'audio/x-pn-realaudio', 
            'ras' => 'image/x-cmu-raster', 
            'rdf' => 'application/rdf+xml', 
            'rgb' => 'image/x-rgb', 
            'rm' => 'application/vnd.rn-realmedia', 
            'roff' => 'application/x-troff', 
            'rtf' => 'text/rtf', 
            'rtx' => 'text/richtext', 
            'sgm' => 'text/sgml', 
            'sgml' => 'text/sgml', 
            'sh' => 'application/x-sh', 
            'shar' => 'application/x-shar', 
            'silo' => 'model/mesh', 
            'sit' => 'application/x-stuffit', 
            'skd' => 'application/x-koan', 
            'skm' => 'application/x-koan', 
            'skp' => 'application/x-koan', 
            'skt' => 'application/x-koan', 
            'smi' => 'application/smil', 
            'smil' => 'application/smil', 
            'snd' => 'audio/basic', 
            'so' => 'application/octet-stream', 
            'spl' => 'application/x-futuresplash', 
            'src' => 'application/x-wais-source', 
            'sv4cpio' => 'application/x-sv4cpio', 
            'sv4crc' => 'application/x-sv4crc', 
            'svg' => 'image/svg+xml', 
            'swf' => 'application/x-shockwave-flash', 
            't' => 'application/x-troff', 
            'tar' => 'application/x-tar', 
            'tcl' => 'application/x-tcl', 
            'tex' => 'application/x-tex', 
            'texi' => 'application/x-texinfo', 
            'texinfo' => 'application/x-texinfo', 
            'tif' => 'image/tiff', 
            'tiff' => 'image/tiff', 
            'tr' => 'application/x-troff', 
            'tsv' => 'text/tab-separated-values', 
            'txt' => 'text/plain', 
            'ustar' => 'application/x-ustar', 
            'vcd' => 'application/x-cdlink', 
            'vrml' => 'model/vrml', 
            'vxml' => 'application/voicexml+xml', 
            'wav' => 'audio/x-wav', 
            'wbmp' => 'image/vnd.wap.wbmp', 
            'wbxml' => 'application/vnd.wap.wbxml', 
            'webm' => 'video/webm', 
            'wml' => 'text/vnd.wap.wml', 
            'wmlc' => 'application/vnd.wap.wmlc', 
            'wmls' => 'text/vnd.wap.wmlscript', 
            'wmlsc' => 'application/vnd.wap.wmlscriptc', 
            'wmv' => 'video/x-ms-wmv', 
            'wrl' => 'model/vrml', 
            'xbm' => 'image/x-xbitmap', 
            'xht' => 'application/xhtml+xml', 
            'xhtml' => 'application/xhtml+xml', 
            'xls' => 'application/vnd.ms-excel', 
            'xml' => 'application/xml', 
            'xpm' => 'image/x-xpixmap', 
            'xsl' => 'application/xml', 
            'xslt' => 'application/xslt+xml', 
            'xul' => 'application/vnd.mozilla.xul+xml', 
            'xwd' => 'image/x-xwindowdump', 
            'xyz' => 'chemical/x-xyz', 
            'zip' => 'application/zip' );

    public static function get_mimetype($ext) {
        return (isset ( self::$mime_types [$ext] ) ? self::$mime_types [$ext] : 'application/octet-stream');
    }
}