PHP如何判断访问来自于手机

/**
 * Test if the current browser runs on a mobile device (smart phone, tablet, etc.)
 *
 * @return bool true|false
 */
function wp_is_mobile() {
    static $is_mobile;

    if ( isset($is_mobile) )
        return $is_mobile;

    if ( empty($_SERVER['HTTP_USER_AGENT']) ) {
        $is_mobile = false;
    } elseif ( strpos($_SERVER['HTTP_USER_AGENT'], 'Mobile') !== false 
        || strpos($_SERVER['HTTP_USER_AGENT'], 'Android') !== false
        || strpos($_SERVER['HTTP_USER_AGENT'], 'Silk/') !== false
        || strpos($_SERVER['HTTP_USER_AGENT'], 'Kindle') !== false
        || strpos($_SERVER['HTTP_USER_AGENT'], 'BlackBerry') !== false
        || strpos($_SERVER['HTTP_USER_AGENT'], 'Opera Mini') !== false
        || strpos($_SERVER['HTTP_USER_AGENT'], 'Opera Mobi') !== false ) {
            $is_mobile = true;
    } else {
        $is_mobile = false;
    }

    return $is_mobile;
}

/**
 * @name: is_wap
 * @description: 是否是wap移动设备访问
 * @return: boolean
**/
function is_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) return TRUE;
    $http_user_agent = isset($_SERVER['HTTP_USER_AGENT']) ? trim($_SERVER['HTTP_USER_AGENT']) : '';
    if($http_user_agent == '') return TRUE;
    $mobile_os = 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 = 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');
    $flag_os = $flag_token = FALSE;
    foreach($mobile_os as $val){
        if(strpos($http_user_agent, $val) > 0){ $flag_os = TRUE; break; }
    }
    foreach($mobile_token as $val){
        if(strpos($http_user_agent, $val) > 0){ $flag_token = TRUE; break; }
    }
    if($flag_os || $flag_token) return TRUE;
    return FALSE;
}