How to get the url for admin page (including the key) in magento 2x custom module controller - magento2

Question

I need the page url in Magento 2x including key in my custom module controller.
here something similar but this is for magento 1x. i need for magento 2x.
for magento 1x : Mage::helper('adminhtml')->getUrl('adminhtml/framexport/index') but i need similar for magento 2x.

Answer 1

The right way is, inject the UrlInterface in you model block or whatever class constructor
Then call the getUrl() function
class SomeClass extends \Some\Other\Class
{
protected $_backendUrl;
public function __construct(
...........
...........
\Magento\Backend\Model\UrlInterface $backendUrl,
...........
) {
$this->_backendUrl = $backendUrl;
}
public function someFunction()
{
$params = array('some'=>'url_parameters');
$url = $this->_backendUrl->getUrl("the/url/path", $params);
}
}

Answer 2

You can easily get Admin url By calling
$this->getUrl('adminhtml/module/action');
Please not that "Context" type of object is loaded in the $this object

Answer 3

You can get admin url as follows:
public function __construct(\Magento\Backend\Helper\Data $HelperBackend
) {
$this->HelperBackend = $HelperBackend;
}
/**
*
* #param \Magento\Framework\Event\Observer $observer
* #return void
*/
public function getAdminUrl()
{
echo $this->HelperBackend->getHomePageUrl();
}

Answer 4

Somehow adminhtml/module creates an extra admin slug which does not work.
My solution is:
// $this->urlBuilder is defined in __constructor() \Magento\Framework\UrlInterface $urlBuilder
$query = [
'method' => 'confirm',
'id' => $order->getEntityId()
];
$url = $this->urlBuilder->getUrl('module', $query);
It works well for secure URLs (with keys) and non-default /admin URLs, such as /backend.