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