How to determine when a Vaadin FileDownloader succeeds or fails

Question

I have Vaadin 7 code to give the user the ability to upload a file:

    Button btnDownloadResults = new Button("Download Results", FontAwesome.CLOUD_DOWNLOAD);
    resource = new StreamResource(new MyStreamResource(), suggestedSaveAsFilename);
    new FileDownloader(resource).extend(btnDownloadResults);

I would like to run the code when the download is successful, or even if the download starts. Used for this: closing the window, starting the progress counter or increasing the number of downloads.

Unlike the Vaadin download component, FileDownloader does not have listeners to find out when a file download fails, runs, or starts.

Here is a simplified version of my StreamResouce subclass:

public class MyStreamResource implements StreamSource {
@Override
public InputStream getStream() {
    String filename = /* code to determine the filename */;

    try {
        final File results = new File(FilenameUtils.normalize(filename));
        return new FileInputStream(results);
    } catch (FileNotFoundException fnfe) {
        String errorMsg = "Cannot download results. Try again later, or contact your sysadmin.";
        Utilities.showError(errorMsg);

        return null;
    } catch (Exception e) {
        Utilities.logAndShowException(e);
        return null;
    }
}
}

Note that the getStream method returns before the user is prompted to save the file (which they can cancel). Therefore, I cannot run anything from within this method.

, , FileDownloader :

FileDownloader fileDownloader = new FileDownloader(fileInputStream) {
    private static final long serialVersionUID = -4584979099145066535L;
    @Override
    public boolean handleConnectorRequest(VaadinRequest request, VaadinResponse response, String path) throws IOException {
        boolean result = super.handleConnectorRequest(request, response, path);
        if (result) {
            /* YOUR LOGIC GOES HERE */
        }
        return result;
    }
} ;

, ( , StreamSource null.)

?

Answer 1

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