#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