PHP獲取當前頁面地址

#測試網址:     http://localhost/blog/testurl.php?id=5

//獲取域名或主機地址 
echo $_SERVER['HTTP_HOST']."<br>"; #localhost

//獲取網頁地址 
echo $_SERVER['PHP_SELF']."<br>"; #/blog/testurl.php

//獲取網址參數 
echo $_SERVER["QUERY_STRING"]."<br>"; #id=5

//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'];
#http://localhost/blog/testurl.php?id=5

//包含端口號的完整url
echo 'http://'.$_SERVER['SERVER_NAME'].':'.$_SERVER["SERVER_PORT"].$_SERVER["REQUEST_URI"]; 
#http://localhost:80/blog/testurl.php?id=5

//只取路徑
$url='http://'.$_SERVER['SERVER_NAME'].$_SERVER["REQUEST_URI"]; 
echo dirname($url);
#http://localhost/blog