判断是否是微信

function is_weixin(){ 
    if ( strpos($_SERVER['HTTP_USER_AGENT'], 'MicroMessenger') !== false ) {
            return true;
    }   
    return false;
}

判断是否是移动端

function isMobile () {
    $_SERVER['ALL_HTTP'] = isset($_SERVER['ALL_HTTP']) ? $_SERVER['ALL_HTTP'] : '';
    $mobile_browser = '0';
    if(preg_match('/(up.browser|up.link|mmp|symbian|smartphone|midp|wap|phone|iphone|ipad|ipod|android|xoom|MicroMessenger|weibo)/i', strtolower($_SERVER['HTTP_USER_AGENT']))) $mobile_browser++;
    if(isset($_SERVER['HTTP_X_WAP_PROFILE'])) $mobile_browser++;
    if(isset($_SERVER['HTTP_PROFILE'])) $mobile_browser++;
    if((isset($_SERVER['HTTP_ACCEPT']) and strpos(strtolower($_SERVER['HTTP_ACCEPT']),'application/vnd.wap.xhtml+xml') !== false)) $mobile_browser++;
    $mobile_ua = strtolower(substr($_SERVER['HTTP_USER_AGENT'],0,4));
    $mobile_agents = array(
        'w3c','acs-','alav','alca','amoi','audi','avan','benq','bird','blac',
        'blaz','brew','cell','cldc','cmd-','dang','doco','eric','hipt','inno',
        'ipaq','java','jigs','kddi','keji','leno','lg-c','lg-d','lg-g','lge-',
        'maui','maxo','midp','mits','mmef','mobi','mot-','moto','mwbp','nec-',
        'newt','noki','oper','palm','pana','pant','phil','play','port','prox',
        'qwap','sage','sams','sany','sch-','sec-','send','seri','sgh-','shar',
        'sie-','siem','smal','smar','sony','sph-','symb','t-mo','teli','tim-',
        'tosh','tsm-','upg1','upsi','vk-v','voda','wap-','wapa','wapi','wapp',
        'wapr','webc','winw','winw','xda','xda-'
        );
    if(in_array($mobile_ua, $mobile_agents)) $mobile_browser++;
    if(strpos(strtolower($_SERVER['ALL_HTTP']), 'operamini') !== false) $mobile_browser++;
    // Pre-final check to reset everything if the user is on Windows
    if(strpos(strtolower($_SERVER['HTTP_USER_AGENT']), 'windows') !== false) $mobile_browser=0;
    // But WP7 is also Windows, with a slightly different characteristic
    if(strpos(strtolower($_SERVER['HTTP_USER_AGENT']), 'windows phone') !== false) $mobile_browser++;
    if($mobile_browser > 0)
        return true;
    else
        return false;
}