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With the upload component, you can access the local file system of the client to select any files and upload them on the server. The component consists of two buttons: the first opens the local file manager and enables the selection of a file, whereas the second starts the upload activity. The name of the selected file will be displayed between the two buttons.

The upload component requires a "receiver" which receives the file on the server side and processes it.

Important properties:
  • ButtonCaption - Label of the upload button.
  • Caption -  Displays text as label.
  • Receiver - The receiver is an object that processes the file on the server side.
  • TabIndex - Defines the sequence in the tab index. The tab index defines the order of several UI components. These can be selected one by one by pressing the Tab key.
Important events
  • uploadFailed - Is triggered when the upload fails.
  • uploadFinished - Is triggered as soon as the upload has ended. At this point, it is still not clear if the upload was successful.
  • updateProgress - Is triggered regularly during the upload. Thus it is possible to track the progress of the upload.
  • uploadStarted - Is triggered as soon as the upload has started.
  • uploadSucceeded - Is triggered as soon as the upload has ended and was successful.
Data binding:
  • No data binding available.
  • File upload

// For later usage, e.g. in a message displayed by uploadSucceeded-Event
File file;

// Build receiver
Receiver receiver = new Receiver() {

	public OutputStream receiveUpload(final String filename, final String mimeType) {
        // Create upload stream to write to

        FileOutputStream fos = null;
        try {

        	// Get path to servlet's temp directory
        	final File temporaryDirectory = (File) VaadinServlet.getCurrent().getServletContext().getAttribute(ServletContext.TEMPDIR);

            // Concatenate temporaryDirectory with filename and open the file for writing.
            file = new File(temporaryDirectory, filename);

        	// Create the output stream
            fos = new FileOutputStream(file);

        } catch (final e) {
  "Could not open file", Type.ERROR_MESSAGE);
            return null;
        return fos;

// Set Receiver for upload component

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