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

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/

我觉得这个方法不错，试试吧

if($_SERVER['HTTP_HOST'] == "localhost"){
    define('SITEURL', 'http://' . $_SERVER['HTTP_HOST']);
    define('SITEPATH', $_SERVER['DOCUMENT_ROOT']);
    define('CSS', $_SERVER['DOCUMENT_ROOT'] . '/css/');
    define('IMAGES', $_SERVER['DOCUMENT_ROOT'] . '/images/');
}
else{
    define('SITEURL', 'http://' . $_SERVER['HTTP_HOST']);
    define('SITEPATH', $_SERVER['DOCUMENT_ROOT']);
    define('TEMPLATE', $_SERVER['DOCUMENT_ROOT'] . '/incs/template/');
    define('CSS', $_SERVER['DOCUMENT_ROOT'] . '/css/');
    define('IMAGES', $_SERVER['DOCUMENT_ROOT'] . '/images/');
}

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

更多信息:如何使用PHP获取页面的完整URL

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'];

简单的使用方法:

$uri = $_SERVER['REQUEST_SCHEME'] . '://' . $_SERVER['HTTP_HOST'].$_SERVER['REQUEST_URI']