Jsf pages to plain/text without header html

I need to show output in a jsf page that is not formatted as html (without header and without html tags), but as a simple text file. This is possible with JSF 2.0 or I necessarily need a servlet? Thanks

EDIT: a client makes a request through url (with parameters) and I have to give it a response. I know that I can use a servlet for this but wanted to know if it was possible to use a Bean/JSF instead. the problem is that I have to give response that can not be an html file but a text file (for simple parsing), but that should not be downloaded but displayed directly in the browser. I hope I was clear

Solution

I know that I can use a servlet for this but wanted to know if it was possible to use a Bean/JSF instead.

Yes, it's quite possible with JSF as well. The entire Facelet page can look like this:

<ui:composition
    xmlns:f="http://java.sun.com/jsf/core"
    xmlns:ui="http://java.sun.com/jsf/facelets">
    <f:event type="preRenderView" listener="#{bean.renderText}" />
</ui:composition>

And the relevant method of the bean can look like this:

public void rendertext() throws IOException {
    FacesContext fc = FacesContext.getCurrentInstance();
    ExternalContext ec = fc.getExternalContext();
    Map<String, String> params = ec.getRequestParameterMap();
    String foo = params.get("foo"); // Returns request parameter with name "foo".
    // ...

    ec.setResponseContentType("text/plain");
    ec.setResponseCharacterEncoding("UTF-8");
    ec.getResponseOutputWriter().write("Some text content");
    // ...

    fc.responseComplete(); // Important! Prevents JSF from proceeding to render HTML.
}

However, you're then essentially abusing JSF as wrong tool for the purpose. JSF adds too much overhead in this specific case which you don't need at all. A servlet is then much better. You can use the @WebServlet annotation to register it without any need for XML configuration. You also don't need a Facelet file anymore.