thinkphp项目中的一个函数解决方法

thinkphp项目中的一个函数
看到别人写的,不知此函数是为什么服务的

function is_mobile() {<br />        $user_agent = $_SERVER['HTTP_USER_AGENT'];<br />        $mobile_agents = Array("240x320","acer","acoon","acs-","abacho","ahong","airness","alcatel","amoi","android","applewebkit/525","applewebkit/532","asus","audio","au-mic","avantogo","becker","benq","bilbo","bird","blackberry","blazer","bleu","cdm-","compal","coolpad","danger","dbtel","dopod","elaine","eric","etouch","fly ","fly_","fly-","go.web","goodaccess","gradiente","grundig","haier","hedy","hitachi","htc","huawei","hutchison","inno","ipad","ipaq","ipod","jbrowser","kddi","kgt","kwc","lenovo","lg ","lg2","lg3","lg4","lg5","lg7","lg8","lg9","lg-","lge-","lge9","longcos","maemo","mercator","meridian","micromax","midp","mini","mitsu","mmm","mmp","mobi","mot-","moto","nec-","netfront","newgen","nexian","nf-browser","nintendo","nitro","nokia","nook","novarra","obigo","palm","panasonic","pantech","philips","phone","pg-","playstation","pocket","pt-","qc-","qtek","rover","sagem","sama","samu","sanyo","samsung","sch-","scooter","sec-","sendo","sgh-","sharp","siemens","sie-","softbank","sony","spice","sprint","spv","symbian","tablet","talkabout","tcl-","teleca","telit","tianyu","tim-","toshiba","tsm","up.browser","utec","utstar","verykool","virgin","vk-","voda","voxtel","vx","wap","wellco","wig browser","wii","windows ce","wireless","xda","xde","zte");<br />        $is_mobile = false;<br />        foreach ($mobile_agents as $device) {<br />            if (stristr($user_agent, $device)) {<br />                $is_mobile = true;<br />                break;<br />            }<br />        }<br />        return $is_mobile;<br />    }<br />	$url = explode('/', $_SERVER['REQUEST_URI']);

------解决思路----------------------
foreach ($mobile_agents as $device) {
            if (stristr($user_agent, $device)) {
                $is_mobile = true;
                break;
            }
        }
遍历 $mobile_agents 数组，检查 $_SERVER['HTTP_USER_AGENT'] 是否包含已知信息