Jarves\Controller\Admin\FileController::viewFileAction PHP Method

    public function viewFileAction(ParamFetcher $paramFetcher)
    {
        $path = $paramFetcher->get('path');
        if (is_numeric($path)) {
            $path = $this->webFilesystem->getPath($path);
        }
        $this->checkAccess($path, ACL::MODE_VIEW);
        $file = $this->webFilesystem->getFile($path);
        if ($file->isDir()) {
            return;
        }
        $ifModifiedSince = $this->pageStack->getRequest()->headers->get('If-Modified-Since');
        if (isset($ifModifiedSince) && strtotime($ifModifiedSince) == $file->getModifiedTime()) {
            // Client's cache IS current, so we just respond '304 Not Modified'.
            $response = new Response();
            $response->setStatusCode(304);
            $response->headers->set('Last-Modified', gmdate('D, d M Y H:i:s', $file->getModifiedTime()) . ' GMT');
            return $response;
        }
        $content = $this->webFilesystem->read($path);
        $mime = $file->getMimeType();
        $expires = 3600;
        //1 h
        $response = new Response();
        $response->headers->set('Content-Type', $mime);
        $response->headers->set('Pragma', 'public');
        $response->headers->set('Cache-Control', 'max-age=' . $expires);
        $response->headers->set('Last-Modified', gmdate('D, d M Y H:i:s', $file->getModifiedTime()) . ' GMT');
        $response->headers->set('Expires', gmdate('D, d M Y H:i:s', time() + $expires) . ' GMT');
        $response->setContent($content);
        return $response;
    }