Laravel Response ::单击按钮时下载不工作且未下载pdf文件

I'm trying to achieve a link in a menu bar, such that when a user clicks on the link, a pdf file will be downloaded automatically, and it should not navigate to other pages.

Inside my main.blade.php, consists of a menu bar, I have this link:

<a href="http://<?php echo $_SERVER['SERVER_NAME']; ?>/php/timetable/public/download">Help</a>

where $_SERVER['SERVER_NAME'] is localhost.

Inside my routes.php:

Route::get('/download', array('uses'=>'MainController@getDownloadHelp'));

Inside my controller called MainController:

public function getDownloadHelp()
{
    $file= public_path(). "/public/download";
    $filename = 'help.pdf';
    $headers = array(
          'Content-Type' => 'application/pdf',
        );
    return Response::download($file, $filename, $headers);
}

The PDF file is stored under /public/download/help.pdf

The problem I'm facing right now is, when I clicked the 'Help' link on the menu bar, it redirects me to localhost/download which is not what I wanted. And also, the pdf is not downloaded.

I really need some help here! Where and what did I went wrong?

You can try to use {{ URL::to('/download') }} instead of $_SERVER['SERVER_NAME']... or in your blade

echo link_to('download', $title, $attributes = array(), $secure = null);

it will write all the <a></a> thing

for the path in the controller maybe you can remove the public in the path of the file like this

public_path() . '/download/';