Excel file response for download excel files usage PHPExcel library (Symfony HttpFoundation)

ExcelFileResponse.php

<?php

namespace Acme\DemoBundle\HttpFoundation;

use Symfony\Component\HttpFoundation\Response;

/**
 * Response for download excel file
 */
class ExcelFileResponse extends Response
{
    /**
     * @var \PHPExcel_Writer_IWriter
     */
    private $writer;

    /**
     * @var string $content
     */
    private $excelContent;

    /**
     * Construct
     *
     * @param \PHPExcel_Writer_IWriter $writer
     * @param string $fileName
     */
    public function __construct(\PHPExcel_Writer_IWriter $writer, $fileName)
    {
        $this->writer = $writer;

        ob_start();
        $writer->save('php://output');
        $this->excelContent = ob_get_contents();
        ob_end_clean();

        parent::__construct(null, 200, array(
            'Content-Disposition' => sprintf('attachment; filename="%s"', $fileName),
            'Content-Length' => mb_strlen($this->excelContent),
            'Content-Type' => 'application/octet-stream; charset=utf-8'
        ));
    }

    /**
     * {@inheritDoc}
     */
    public function sendContent()
    {
        print $this->excelContent;

        return $this;
    }
}

I've updated this snippet: Updated XlsxResponse.php