php怎么判断网页是电脑访问还是手机访问

1.第一种方法 

<?php 

function check_wap() {  
    if (isset($_SERVER['HTTP_VIA'])) return true;  
    if (isset($_SERVER['HTTP_X_NOKIA_CONNECTION_MODE'])) return true;  
    if (isset($_SERVER['HTTP_X_UP_CALLING_LINE_ID'])) return true;  
    if (strpos(strtoupper($_SERVER['HTTP_ACCEPT']),"VND.WAP.WML") > 0) {  
        // Check whether the browser/gateway says it accepts WML.  
        $br = "WML";  
    } else {  
        $browser = isset($_SERVER['HTTP_USER_AGENT']) ? trim($_SERVER['HTTP_USER_AGENT']) : '';  
        if(empty($browser)) return true;
        $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,$browser) ||  
                            checkSubstrs($mobile_token_list,$browser); 
    if($found_mobile)
        $br ="WML";
    else $br = "WWW";
    }  
    if($br == "WML") {  
        return true;  
    } else {  
        return false;  
    }  
}

function checkSubstrs($list,$str){
    $flag = false;
    for($i=0;$i<count($list);$i++){
        if(strpos($str,$list[$i]) > 0){
            $flag = true;
            break;
        }
    }
    return $flag;
}

if(check_wap()){
    echo "wap";
}else{
    echo "web";
}

?>

 2.第二种方法

<?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';
else
    echo '电脑登录';

?>