PHP识别电脑还是手机访问网站

<?php
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())
    echo '手机登录www.baidu.com';
else
    echo '电脑登录www.baidu.com';
?>