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.
• 
• Receiver - The receiver is an object that processes the file on the server side.
• 

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.

Examples:

• File upload

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


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

	@Override
	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 java.io.FileNotFoundException e) {
            Notification.show("Could not open file", Type.ERROR_MESSAGE);
            return null;
        }
        return fos;
	}
};

// Set Receiver for upload component
upload.setReceiver(receiver);