Downloading a CSV file using JSF
csv, download, java, jsf
Solution
Do I need to save the file in the tomcat WEB-INF directory first?
No, just write it straight to the HTTP response body as you obtain by `ExternalContext#getResponseOutputStream()` after having set the proper response headers which tells the browser what it's going to retrieve.
Do the math based on the concrete examples found in the following answers:
- How to provide a file download from a JSF backing bean?
- JSP generating Excel spreadsheet (XLS) to download
Basically:
List<List<Object>> csv = createItSomehow();
writeCsv(csv, ';', ec.getResponseOutputStream());
By the way, what's the favorite jsf-component for this kind of task?
This is subjective. But anyway, we're using `<p:dataExporter>` to full satisfaction.
Problem
I don't know how to download a CSV file. The CSV will be generated at runtime. Do I need to save the file in the tomcat WEB-INF directory first? I'm using JSF 1.2. By the way, what's the favored JSF component for this kind of task? Edit (05.05.2012 - 15:53) I tried the solution `BalusC` stated in his first link, but if I click on my commandButton the content of the file is displayed on the webpage. Maybe there's a problem with the `mimetype`? xhtml-file: ``` <a4j:form> <a4j:commandButton action="#{surveyEvaluationBean.doDataExport}" value="#{msg.srvExportButton}" /> </a4j:form> ``` main bean: ``` public String doDataExport() { try { export.downloadFile(); } catch (SurveyException e) { hasErrors = true; } return ""; } ``` export-bean: ``` public void downloadFile() throws SurveyException { try { String filename = "analysis.csv"; FacesContext fc = FacesContext.getCurrentInstance(); HttpServletResponse response = (HttpServletResponse) fc.getExternalContext().getResponse(); response.reset(); response.setContentType("text/comma-separated-values"); response.setHeader("Content-Disposition", "attachment; filename=\"" + filename + "\""); OutputStream output = response.getOutputStream(); // writing just sample data List<String> strings = new ArrayList<String>(); strings.add("filename" + ";" + "description" + "\n"); strings.add(filename + ";" + "this is just a test" + "\n"); for (String s : strings) { output.write(s.getBytes()); } output.flush(); output.close(); fc.responseComplete(); } catch (IOException e) { throw new SurveyException("an error occurred"); } } ``` Edit (05.05.2012 - 16:27) I solved my problem. I have to use `<h:commandButton>` instead of `<a4j:commandButton>` and now it works!