/**
 * 根据文件后缀获取其mine类型
 *
 * @author 编程之家 jb51.cc jb51.cc
 * @param string $extension
 * @return string
 */
 function get_mimetype($extension) {
 $ct['htm'] = 'text/html';
 $ct['html'] = 'text/html';
 $ct['txt'] = 'text/plain';
 $ct['asc'] = 'text/plain';
 $ct['bmp'] = 'image/bmp';
 $ct['gif'] = 'image/gif';
 $ct['jpeg'] = 'image/jpeg';
 $ct['jpg'] = 'image/jpeg';
 $ct['jpe'] = 'image/jpeg';
 $ct['png'] = 'image/png';
 $ct['ico'] = 'image/vnd.microsoft.icon';
 $ct['mpeg'] = 'video/mpeg';
 $ct['mpg'] = 'video/mpeg';
 $ct['mpe'] = 'video/mpeg';
 $ct['qt'] = 'video/quicktime';
 $ct['mov'] = 'video/quicktime';
 $ct['avi'] = 'video/x-msvideo';
 $ct['wmv'] = 'video/x-ms-wmv';
 $ct['mp2'] = 'audio/mpeg';
 $ct['mp3'] = 'audio/mpeg';
 $ct['rm'] = 'audio/x-pn-realaudio';
 $ct['ram'] = 'audio/x-pn-realaudio';
 $ct['rpm'] = 'audio/x-pn-realaudio-plugin';
 $ct['ra'] = 'audio/x-realaudio';
 $ct['wav'] = 'audio/x-wav';
 $ct['css'] = 'text/css';
 $ct['zip'] = 'application/zip';
 $ct['pdf'] = 'application/pdf';
 $ct['doc'] = 'application/msword';
 $ct['bin'] = 'application/octet-stream';
 $ct['exe'] = 'application/octet-stream';
 $ct['class'] = 'application/octet-stream';
 $ct['dll'] = 'application/octet-stream';
 $ct['xls'] = 'application/vnd.ms-excel';
 $ct['ppt'] = 'application/vnd.ms-powerpoint';
 $ct['wbxml'] = 'application/vnd.wap.wbxml';
 $ct['wmlc'] = 'application/vnd.wap.wmlc';
 $ct['wmlsc'] = 'application/vnd.wap.wmlscriptc';
 $ct['dvi'] = 'application/x-dvi';
 $ct['spl'] = 'application/x-futuresplash';
 $ct['gtar'] = 'application/x-gtar';
 $ct['gzip'] = 'application/x-gzip';
 $ct['js'] = 'application/x-javascript';
 $ct['swf'] = 'application/x-shockwave-flash';
 $ct['tar'] = 'application/x-tar';
 $ct['xhtml'] = 'application/xhtml+xml';
 $ct['au'] = 'audio/basic';
 $ct['snd'] = 'audio/basic';
 $ct['midi'] = 'audio/midi';
 $ct['mid'] = 'audio/midi';
 $ct['m3u'] = 'audio/x-mpegurl';
 $ct['tiff'] = 'image/tiff';
 $ct['tif'] = 'image/tiff';
 $ct['rtf'] = 'text/rtf';
 $ct['wml'] = 'text/vnd.wap.wml';
 $ct['wmls'] = 'text/vnd.wap.wmlscript';
 $ct['xsl'] = 'text/xml';
 $ct['xml'] = 'text/xml';
 
 return isset($ct[strtolower($extension)]) ? $ct[strtolower($extension)] : 'text/html';
}