PHP判断用户是手机端？还是浏览器端访问？

function isMobile(){ 
    $useragent=isset($_SERVER['HTTP_USER_AGENT']) ? $_SERVER['HTTP_USER_AGENT'] : ''; 
    $useragent_commentsblock=preg_match('|\(.*?\)|',$useragent,$matches)>0?$matches[0]:'';       
    function CheckSubstrs($substrs,$text){ 
        foreach($substrs as $substr) 
            if(false!==strpos($text,$substr)){ 
                return true; 
            } 
            return false; 
    }
    $mobile_os_list=array('Google Wireless Transcoder','Windows CE','WindowsCE','Symbian','Android','armv6l','armv5','Mobile','CentOS','mowser','AvantGo','Opera Mobi','J2ME/MIDP','Smartphone','Go.Web','Palm','iPAQ');
    $mobile_token_list=array('Profile/MIDP','Configuration/CLDC-','160×160','176×220','240×240','240×320','320×240','UP.Browser','UP.Link','SymbianOS','PalmOS','PocketPC','SonyEricsson','Nokia','BlackBerry','Vodafone','BenQ','Novarra-Vision','Iris','NetFront','HTC_','Xda_','SAMSUNG-SGH','Wapaka','DoCoMo','iPhone','iPod'); 
  
    $found_mobile = CheckSubstrs($mobile_os_list,$useragent_commentsblock) ||  CheckSubstrs($mobile_token_list,$useragent); 
  
    if ($found_mobile){ 
         return true; 
    }else{ 
         return false; 
    } 
}
if (isMobile()){
    header('location: ./app/index.php');//如果为手机端，执行跳转
}
else{
    header('location: ./web/index.php');//如果非手机端，执行跳转
}