<p>How Can I put information in a outputstream from tapestry5 ?</p>

<p>I need a page when a user enters it open a dialog for save or open the file with the outputstream information.</p>

<p>I write the next code:</p>

<p>public class Index {</p>

<pre><code>@Inject
private RequestGlobals requestGlobals;

@OnEvent("activate")
public void onActivate() {
    try {
        HttpServletResponse response = requestGlobals.getHTTPServletResponse();
        response.setContentType("text/txt");
        PrintWriter out = response.getWriter();
        out.println("hellooooooo");
        out.flush();
    } catch (IOException ex) {
        Logger.getLogger(Index.class.getName()).log(Level.SEVERE, null, ex);
    }
}
</code></pre>

<p>}</p>

<p>I hope that the result is only "helloooooooo" but is ("helloooooooo" + my html raw page)</p>

Your method should have a return type of StreamResponse. You return an implementation of the interface StreamResponse, which simply returns the data you want with the content type you want.
Look it up here:
http://tapestry.apache.org/tapestry5/apidocs/
more info here:
http://tapestry.formos.com/nightly/tapestry5/tapestry-core/guide/pagenav.html