PHP中获取当前页面的完整URL

javascript实现：

top.location.href //顶级窗口的地址
this.location.href //当前窗口的地址

#测试网址:
http://localhost/blog/testurl.php?id=5

//获取域名或主机地址

echo $_SERVER['HTTP_HOST'];
#localhost

//获取网页地址
echo $_SERVER['PHP_SELF'];
#/blog/testurl.php

//获取网址参数
echo $_SERVER["QUERY_STRING"];
#id=5

//获取网页地址和网址参数
echo $_SERVER['REQUEST_URI']
#/blog/testurl.php?id=5

//获取用户代理
echo $_SERVER['HTTP_REFERER'];

//获取完整的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

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