Cancel download method when the user cancel the download file

Question

I have a method that download a file ("downloadLog_action()")when the user click over the comandlink component and the dialog box is opening to save the file, but how to know that the user canceled the download file to cancel all accions.
This is the code of the commandlink in the jspx page that call the method and pass one parameter:
<af:commandLink binding="#{ConsultaValidacion.commandLink1}"
id="commandLink1"
action="#{ConsultaValidacion.descargarLog_action}"
text="Log">
<f:param name="codInstitucion"
value="#{row.CodInstitucion}"
binding="#{ConsultaValidacion.codInstitucion}"
id="codInstitucion"/>
</af:commandLink>
This is the method to download the file:
HttpServletResponse response = (HttpServletResponse)fctx.getExternalContext().getResponse();
response.setContentType("application/x-download");
response.setHeader("Content-Disposition", "attachement; filename=\"Log_" +
codigoInstitucion + ".txt\"");
response.setContentLength((new Long(blob.getLength())).intValue());
//Streams de entrada y salida
InputStream is;
OutputStream out;
try {
//Obtenemos el stream de entrada el cual se lo extrae de la BD
is = blob.getInputStream();
//Obtenemos el stream de salida para el cliente
out = response.getOutputStream();
//Sección de código que me permite escribir los datos en el stream de salida
int size = (new Long(blob.getLength())).intValue();
byte[] buffer = new byte[size];
int length = -1;
while ((length = is.read(buffer)) != -1) {
out.write(buffer, 0, length);
//Cerramos los streams
out.flush();
is.close();
out.close();
*//Una vez descargado todo el LOG actualizamos el contador. HERE IS THE PROBLEM BECAUSE THE COUNTER IS UPDATING WHEN THE USER CANCEL THE DOWNLOAD!!! AND ITS WRONG*
row.setNumDescargaLog(new Number(num + 1));
//Guardamos los cambios
webRvc.getAppModuleWebRvc().getDBTransaction().commit();
//Request lifecyce understands that the response is completed and no further action needs to happen
fctx.responseComplete();
} catch (IOException e) {
e.printStackTrace();
webRvc.close("Consulta bitacoras validacion");
return null;
} catch (JboException ex) {
webRvc.getAppModuleWebRvc().getDBTransaction().rollback();
webRvc.close("Consulta bitacoras validacion");
return null;
This works fine.
The problem occurs when the user cancels the download, because all the sentences run including updating the counter downloads, the counter only to be updated only when the user chooses to save the file.

Answer 1

Hi.
The problem is when the user cancel the dowload I do not know how to capture the user's response.
How to capture the response?
if(cancelled) <------Is there a parameter to tell me this?
......<your cancel code>..... none
else
.....<your non-cancel code>...THE METHOD THAT DOWNLOAD THE FILE - "downloadLog_action()" and increment the counter
Thanks.