/**
* 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';
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