PHP中擷取目前頁面的完整URL

javascript實作：

top.location.href   頂級視窗的位址
this.location.href  目前視窗的位址      

PHP實作      

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

//擷取域名或主機位址 
echo $_SERVER['HTTP_HOST']."<br>"; #localhost

//擷取網頁位址 
echo $_SERVER['PHP_SELF']."<br>"; #/blog/testurl.php

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

//擷取使用者代理 
echo $_SERVER['HTTP_REFERER']."<br>"; 

//擷取完整的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

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

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