Creating a file using ByteArrayOutputStream.writeTo(FileOutputStream) fails when using Vaadin StreamVariable in DropHandler?

Question

I am learning Vaadin from the Vaadin 7 CookBook, on chapter 3 the authors show an example of a drag and drop uploader using StreamVariable and Html5File, here is the code:

public class DragAndDropUploader extends VerticalLayout {

    /**
     * 
     */
    private static final long serialVersionUID = 1L;

    private static final String REPOSITORY = VaadinService.getCurrent().getBaseDirectory().getAbsolutePath()+"/WEB-INF/vaadin-repo/";

    public DragAndDropUploader() {
        final Table table = new Table();
        table.setSizeFull();
        table.addContainerProperty("File name", String.class, null);
        table.addContainerProperty("Size", String.class, null);
        table.addContainerProperty("Progress", ProgressBar.class, null);

        DragAndDropWrapper dropTable = new DragAndDropWrapper(table);
        dropTable.setDropHandler(new DropHandler() {

            /**
             * 
             */
            private static final long serialVersionUID = 1L;

            @Override
            public void drop(DragAndDropEvent event) {
                WrapperTransferable transferred = (WrapperTransferable) event.getTransferable();
                Html5File[] files = transferred.getFiles();
                if (files != null) {
                    for (Html5File file : files) {
                        ProgressBar progressBar = new ProgressBar();
                        progressBar.setSizeFull();
                        UI.getCurrent().setPollInterval(100);
                        table.addItem(new Object[] { file.getFileName(), 
                                                     getSizeAsString(file.getFileSize()),
                                                     progressBar
                        }, null);

                        StreamVariable streamVariable = createStreamVariable(file, progressBar);

                        file.setStreamVariable(streamVariable);
                    }
                }
                else {
                    Notification.show("Usupported file type", Type.ERROR_MESSAGE);
                }
            }

            @Override
            public AcceptCriterion getAcceptCriterion() {
                return AcceptAll.get();
            }

        }); 
        addComponent(dropTable);
        setSizeUndefined();
    }

    private StreamVariable createStreamVariable(final Html5File file, final ProgressBar progressBar) {
        final ByteArrayOutputStream outputStream = new ByteArrayOutputStream();

        return new StreamVariable() {

            /**
             * 
             */
            private static final long serialVersionUID = 1L;

            @Override
            public void streamingStarted(StreamingStartEvent event) {                               
            }

            @Override
            public void streamingFinished(StreamingEndEvent event) {
                try {
                    FileOutputStream fos = new FileOutputStream(REPOSITORY+file.getFileName());                 
                    System.out.println(outputStream.size()+ ": "+outputStream.toString() + " - " +fos.toString());
                    outputStream.writeTo(fos);
                } catch (IOException e) {
                    Notification.show("Streaming finished failing, please, retry", Type.ERROR_MESSAGE);
                }
                progressBar.setValue(new Float(1.0));
            }

            @Override
            public void streamingFailed(StreamingErrorEvent event) {
                Notification.show("Streaming failed, please, try again", Type.ERROR_MESSAGE);
            }

            @Override
            public void onProgress(StreamingProgressEvent event) {
                progressBar.setValue((float) event.getBytesReceived() / file.getFileSize());
            }

            @Override
            public boolean listenProgress() {
                return true;
            }

            @Override
            public boolean isInterrupted() {
                return false;
            }

            @Override
            public OutputStream getOutputStream() {
                return outputStream;
            }
        };
    }

    private String getSizeAsString(long size) {
        String unit = "B";
        int kB, MB;
        if (size >= (kB = (2 << 10))) {
            size = size / kB;
            unit = "kB";
        }
        else if (size >= (MB = 2 << 20)) {
            size = size / MB;
        }
        return size + " " + unit;
    }
}

REPOSITORY is a path to a vaadin-repo folder inside WebContent/WEB-INF .

My problem is that outputStream.writeTo(fos); where actually the file should be written to the server:

    @Override
    public void streamingFinished(StreamingEndEvent event) {
        try {
            FileOutputStream fos = new FileOutputStream(REPOSITORY+file.getFileName());                 
            System.out.println(outputStream.size()+ ": "+outputStream.toString() + " - " +fos.toString());
            outputStream.writeTo(fos);
        } catch (IOException e) {
            Notification.show("Streaming finished failing, please, retry", Type.ERROR_MESSAGE);
        }
        progressBar.setValue(new Float(1.0));
    }

But it's not. When I make an upload and then check that vaadin-repo folder, it remains empty...

I do not get any exceptions (no FileNotFoundException, no IOException), so the problem is not that. REPOSITORY path have some spaces (but I think that this is not the problem (as I said I don't get any FileNotFoundException), and I have implemented Vaadin's uploaders previously (via the Upload.Receiver inner interface)).

Where is the problem?

Answer 1

Your code seems to be correct and a similar version is working for me. The only problem seems to be that you're not closing the streams. Make sure you close both outputstream and the FileOutputStream fos .