php 獲取域名等Url

<?php
//獲取域名或主機地址
echo $_SERVER['HTTP_HOST']."<br />";
//獲取網頁地址
echo $_SERVER['PHP_SELF']."<br />";
//獲取網址參數
echo $_SERVER["QUERY_STRING"]."<br />";
//獲取用戶代理
echo $_SERVER['HTTP_REFERER']."<br />";
//獲取完整的url
echo 'http://'.$_SERVER['HTTP_HOST'].$_SERVER['REQUEST_URI'];
echo 'http://'.$_SERVER['HTTP_HOST'].$_SERVER['PHP_SELF'].'?'.$_SERVER['QUERY_STRING'];
//包含端口號的完整url
echo 'http://'.$_SERVER['SERVER_NAME'].':'.$_SERVER["SERVER_PORT"].$_SERVER["REQUEST_URI"];
//只取路徑
$url='http://'.$_SERVER['SERVER_NAME'].$_SERVER["REQUEST_URI"];
echo dirname($url);
?>