根据文件后缀获取mime类型

/**
 * 根据文件后缀获取mime类型
 * @param  string $ext 文件后缀
 * @return string      mime类型
 */
function get_mime_type($ext){
    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' 
    );
    
    return isset($mime_types[$ext]) ? $mime_types[$ext] : 'application/octet-stream';
}