How to create download button?

Allow the title.
How I can do it with Vaadin 14 Spring and Java.
I search a lot of Forum and do it all I can.
But that not works.

I Just do it works.
Cr. My senior.

public void download() throws FileNotFoundException {
        InputStream inputStream = new FileInputStream(
                new File("C:/Users/44606/Desktop/novel/QQ farm/CH 1 - 90.pdf"));
        StreamResource resource = new StreamResource("123.pdf", () -> inputStream);
        Anchor link = new Anchor(resource,"");
        link.getElement().setAttribute("download", true);
        link.add(new Button(new Icon(VaadinIcon.DOWNLOAD_ALT)));