---

版本一：$root = ($_SERVER[‘SERVER_PORT’] == 443 ? ‘https’ : ‘http’);

---

版本二：$root = “http”.((isset($_SERVER[‘HTTPS’]) && $_SERVER[‘HTTPS’] == “on”) ? “s” : “”);

---

版本三：$root = (empty($_SERVER[‘HTTPS’]) OR strtolower($_SERVER[‘HTTPS’]) === ‘off’) ? ‘http’ : ‘https’;

版本四：
$isSecure = false;
if (isset($_SERVER[‘HTTPS’]) && $_SERVER[‘HTTPS’] == ‘on’) {
$isSecure = true;
}
elseif (!empty($_SERVER[‘HTTP_X_FORWARDED_PROTO’]) && $_SERVER[‘HTTP_X_FORWARDED_PROTO’] == ‘https’ || !empty($_SERVER[‘HTTP_X_FORWARDED_SSL’]) && $_SERVER[‘HTTP_X_FORWARDED_SSL’] == ‘on’) {
$isSecure = true;
}
$root = $isSecure ? ‘https’ : ‘http’;

我也放了一份在 gist上面 唷
下一篇應該就會解釋這四種方法為什麼可以用，為什麼不能用了