PHP判断是不是手机访问的函数

网上找来一个PHP判断是不是手机访问的函数
function is_mobile(){ $_SERVER['ALL_HTTP'] = isset($_SERVER['ALL_HTTP']) ? $_SERVER['ALL_HTTP'] : ''; $mobile_browser = '0'; if(preg_match('/(up.browser|up.link|mmp|symbian|smartphone|midp|wap|phone|iphone|ipad|ipod|android|xoom)/i', strtolower($_SERVER['HTTP_USER_AGENT'])))  $mobile_browser++; if((isset($_SERVER['HTTP_ACCEPT'])) and (strpos(strtolower($_SERVER['HTTP_ACCEPT']), 'application/vnd.wap.xhtml+xml') !== false))  $mobile_browser++; if(isset($_SERVER['HTTP_X_WAP_PROFILE']))  $mobile_browser++; if(isset($_SERVER['HTTP_PROFILE']))  $mobile_browser++; $mobile_ua = strtolower(substr($_SERVER['HTTP_USER_AGENT'], 0, 4)); $mobile_agents = array(     'w3c ','acs-','alav','alca','amoi','audi','avan','benq','bird','blac',     'blaz','brew','cell','cldc','cmd-','dang','doco','eric','hipt','inno',     'ipaq','java','jigs','kddi','keji','leno','lg-c','lg-d','lg-g','lge-',     'maui','maxo','midp','mits','mmef','mobi','mot-','moto','mwbp','nec-',     'newt','noki','oper','palm','pana','pant','phil','play','port','prox',     'qwap','sage','sams','sany','sch-','sec-','send','seri','sgh-','shar',     'sie-','siem','smal','smar','sony','sph-','symb','t-mo','teli','tim-',     'tosh','tsm-','upg1','upsi','vk-v','voda','wap-','wapa','wapi','wapp',     'wapr','webc','winw','winw','xda','xda-' ); if(in_array($mobile_ua, $mobile_agents))  $mobile_browser++; if(strpos(strtolower($_SERVER['ALL_HTTP']), 'operamini') !== false)  $mobile_browser++;// Pre-final check to reset everything if the user is on Windows if(strpos(strtolower($_SERVER['HTTP_USER_AGENT']), 'windows') !== false)  $mobile_browser = 0;// But WP7 is also Windows, with a slightly different characteristic if(strpos(strtolower($_SERVER['HTTP_USER_AGENT']), 'windows phone') !== false)  $mobile_browser++; if($mobile_browser > 0)  return true; else  return false;}
函数就是这个了，使用方法if(!is_mobile()){   echo "非手机访问";exit; }