PHP获取当前页面的url

这两天因工作需要，要把用户对网站的访问页面做统计，研究了一下php中获取url的方式：

//获取域名或主机地址
echo $_SERVER['HTTP_HOST']."
";#localhost

//获取网页网址
echo $_SERVER['PHP_SELF']."
";

//获取网址参数
echo $_SERVER['QUERY_STRING']."
";

//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']."
";

//包含端口号的完整url
echo 'http://'.$_SERVER['SERVER_NAME'].':'.$_SERVER["SERVER_PORT"].$_SERVER["REQUEST_URI"]."
";

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