Download file vaadin

Question

I made a taable which has its data source set to a BeanItemContainer. Each bean has a name (String) and a byte[] which holds a file converted to a byte[]. I added a button to each row which is suppose to download the file by first converting it to a pdf. I am having trouble implementing the downloading part here is the code relating:

public Object generateCell(Table source, Object itemId,
                Object columnId) {
            // TODO Auto-generated method stub
            final Beans p = (Beans) itemId;

            Button l = new Button("Link to pdf");
            l.addClickListener(new Button.ClickListener() {

                @Override
                public void buttonClick(ClickEvent event) {
                    // TODO Auto-generated method stub

                    try {
                        FileOutputStream out = new FileOutputStream(p.getName() + ".pdf");
                        out.write(p.getFile());
                        out.close();

                    } catch (Exception e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }
                }
            });
            l.setStyleName(Reindeer.BUTTON_LINK);

            return l;
        }


    });

So getFile gets the byte array from the bean

Answer 1

If you are using Vaadin 7 you can use FileDownloader extension as described here: https://vaadin.com/forum#!/thread/2864064

Instead of using a clicklistener you would need to extend the button instead:

Button l = new Button("Link to pdf");
StreamResource sr = getPDFStream();
FileDownloader fileDownloader = new FileDownloader(sr);
fileDownloader.extend(l);

To get the StreamResource:

private StreamResource getPDFStream() {
        StreamResource.StreamSource source = new StreamResource.StreamSource() {

            public InputStream getStream() {
                // return your file/bytearray as an InputStream
                  return input;

            }
        };
      StreamResource resource = new StreamResource ( source, getFileName());
        return resource;
}

Answer 2

Generated columns creation is well described in Book of Vaadin, one correction to your code would be to check columnId or propertyId to ensure you create a button in right column - currently it seems you return a button for any column.

Something like this:

    public Object generateCell(CustomTable source, Object itemId, Object columnId)
    {
        if ("Link".equals(columnId))
        {
            // ...all other button init code is omitted...
            return new Button("Download");
        }
        return null; 
    }

To download a file:

    // Get instance of the Application bound to this thread
    final YourApplication app = getCurrentApplication();
    // Generate file basing on your algorithm
    final File pdfFile = generateFile(bytes);
    // Create a resource
    final FileResource res = new FileResource(pdfFile, app);
    // Open a resource, you can also specify target explicitly - 
    // i.e. _blank, _top, etc... Below code will just try to open 
    // in same window which will just force browser to show download
    // dialog to user
    app.getMainWindow().open(res);

More info on how to deal with resources can be found in Book of Vaadin.