PHP类库：获取用户真实ip

// 即使使用代理服务器，也能获取用户真实ip
public function getIp()
{
    $unknown = 'unknown';
    if (isset($_SERVER['HTTP_X_FORWARDED_FOR']) && $_SERVER['HTTP_X_FORWARDED_FOR'] && strcasecmp($_SERVER['HTTP_X_FORWARDED_FOR'], $unknown)) {
        $ip = $_SERVER['HTTP_X_FORWARDED_FOR'];
    } elseif (isset($_SERVER['REMOTE_ADDR']) && $_SERVER['REMOTE_ADDR'] && strcasecmp($_SERVER['REMOTE_ADDR'], $unknown)) {
        $ip = $_SERVER['REMOTE_ADDR'];
    }
    if (false !== strpos($ip, ',')) {
        $ip = reset(explode(',', $ip));
    }
 
    return $ip;
}