javascript实现：
top.location.href 顶级窗口的地址
this.location.href 当前窗口的地址
php实现
PHP实现#测试网址: http://localhost/blog/testurl.php?id=5
//获取域名或主机地址
echo $_SERVER[\'HTTP_HOST\']."<br>"; #localhost
//获取网页地址
echo $_SERVER[\'PHP_SELF\']."<br>"; #/blog/testurl.php
//获取网址参数
echo $_SERVER["QUERY_STRING"]."<br>"; #id=5
//获取用户代理
echo $_SERVER[\'HTTP_REFERER\']."<br>";
//获取完整的url
echo \'http://\'.$_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