我最喜欢的查找当前URL的跨平台方法是:

$url = (isset($_SERVER['HTTPS']) ? "https" : "http") . "://$_SERVER[HTTP_HOST]$_SERVER[REQUEST_URI]";

你可以使用HTTP_ORIGIN，如下面的代码片段所示:

if ( ! array_key_exists( 'HTTP_ORIGIN', $_SERVER ) ) {
    $this->referer = $_SERVER['SERVER_NAME'];
} else {
    $this->referer = $_SERVER['HTTP_ORIGIN'];
}

Use:

$base_dir = __DIR__; // Absolute path to your installation, ex: /var/www/mywebsite
$doc_root = preg_replace("!{$_SERVER['SCRIPT_NAME']}$!", '', $_SERVER['SCRIPT_FILENAME']); # ex: /var/www
$base_url = preg_replace("!^{$doc_root}!", '', $base_dir); # ex: '' or '/mywebsite'
$base_url = str_replace('\\', '/', $base_url);//On Windows
$base_url = str_replace($doc_root, '', $base_url);//On Windows
$protocol = empty($_SERVER['HTTPS']) ? 'http' : 'https';
$port = $_SERVER['SERVER_PORT'];
$disp_port = ($protocol == 'http' && $port == 80 || $protocol == 'https' && $port == 443) ? '' : ":$port";
$domain = $_SERVER['SERVER_NAME'];
$full_url = "$protocol://{$domain}{$disp_port}{$base_url}"; # Ex: 'http://example.com', 'https://example.com/mywebsite', etc. 

来源:PHP文档根，路径和URL检测

看一下$_SERVER['REQUEST_URI']，即

$actual_link = "http://$_SERVER[HTTP_HOST]$_SERVER[REQUEST_URI]";

(注意双引号字符串语法是完全正确的)

如果你想同时支持HTTP和HTTPS，你可以使用

$actual_link = (isset($_SERVER['HTTPS']) && $_SERVER['HTTPS'] === 'on' ? "https" : "http") . "://$_SERVER[HTTP_HOST]$_SERVER[REQUEST_URI]";

编者注:使用此代码具有安全隐患。客户端可以将HTTP_HOST和REQUEST_URI设置为它想要的任意值。

清晰的代码，工作在所有的web服务器(Apache, nginx, IIS，…)

$url = (isset($_SERVER['HTTPS']) && $_SERVER['HTTPS'] !== 'off' ? 'https' : 'http') . '://' . $_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI'];

这是我的解决方案-代码的灵感来自特雷西调试器。更改为支持不同的服务器端口。您可以获得完整的当前URL，包括$_SERVER['REQUEST_URI']或只是基本的服务器URL。检查我的函数:

function getCurrentUrl($full = true) {
    if (isset($_SERVER['REQUEST_URI'])) {
        $parse = parse_url(
            (isset($_SERVER['HTTPS']) && strcasecmp($_SERVER['HTTPS'], 'off') ? 'https://' : 'http://') .
            (isset($_SERVER['HTTP_HOST']) ? $_SERVER['HTTP_HOST'] : (isset($_SERVER['SERVER_NAME']) ? $_SERVER['SERVER_NAME'] : '')) . (($full) ? $_SERVER['REQUEST_URI'] : null)
        );
        $parse['port'] = $_SERVER["SERVER_PORT"]; // Setup protocol for sure (80 is default)
        return http_build_url('', $parse);
    }
}

下面是测试代码:

// Follow $_SERVER variables was set only for test
$_SERVER['HTTPS'] = 'off'; // on
$_SERVER['SERVER_PORT'] = '9999'; // Setup
$_SERVER['HTTP_HOST'] = 'some.crazy.server.5.name:8088'; // Port is optional there
$_SERVER['REQUEST_URI'] = '/150/tail/single/normal?get=param';

echo getCurrentUrl();
// http://some.crazy.server.5.name:9999/150/tail/single/normal?get=param

echo getCurrentUrl(false);
// http://some.crazy.server.5.name:9999/