php获取当前网页地址，获取服务器，获取目录

/**
     * 判断是否为https
     * @return bool 是https返回true;否则返回false
     */
    function is_https() {
        if ( !empty($_SERVER['HTTPS']) && strtolower($_SERVER['HTTPS']) !== 'off') {
            return true;
        } elseif ( isset($_SERVER['HTTP_X_FORWARDED_PROTO']) && $_SERVER['HTTP_X_FORWARDED_PROTO'] === 'https' ) {
            return true;
        } elseif ( !empty($_SERVER['HTTP_FRONT_END_HTTPS']) && strtolower($_SERVER['HTTP_FRONT_END_HTTPS']) !== 'off') {
            return true;
        }else{
            return false;
        }
    }
//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