哪位高手用过swing进度条显示文件上传进度吗

import java.awt.*;import java.awt.event.*;import javax.swing.*;import java.beans.*;import java.util.Random;public class ProgressBarDemo extends JPanel                             implements ActionListener,                                         PropertyChangeListener {    private JProgressBar progressBar;    private JButton startButton;    private JTextArea taskOutput;    private Task task;    class Task extends SwingWorker<Void, Void> {        /*         * Main task. Executed in background thread.         */        @Override        public Void doInBackground() {            Random random = new Random();            int progress = 0;            //Initialize progress property.            setProgress(0);            while (progress < 100) {                //Sleep for up to one second.                try {                    Thread.sleep(random.nextInt(1000));                } catch (InterruptedException ignore) {}                //Make random progress.                progress += random.nextInt(10);                setProgress(Math.min(progress, 100));            }            return null;        }        /*         * Executed in event dispatching thread         */        @Override        public void done() {            Toolkit.getDefaultToolkit().beep();            startButton.setEnabled(true);            setCursor(null); //turn off the wait cursor            taskOutput.append("Done!\n");        }    }    public ProgressBarDemo() {        super(new BorderLayout());        //Create the demo's UI.        startButton = new JButton("Start");        startButton.setActionCommand("start");        startButton.addActionListener(this);        progressBar = new JProgressBar(0, 100);        progressBar.setValue(0);        progressBar.setStringPainted(true);        taskOutput = new JTextArea(5, 20);        taskOutput.setMargin(new Insets(5,5,5,5));        taskOutput.setEditable(false);        JPanel panel = new JPanel();        panel.add(startButton);        panel.add(progressBar);        add(panel, BorderLayout.PAGE_START);        add(new JScrollPane(taskOutput), BorderLayout.CENTER);        setBorder(BorderFactory.createEmptyBorder(20, 20, 20, 20));    }    /**     * Invoked when the user presses the start button.     */    public void actionPerformed(ActionEvent evt) {        startButton.setEnabled(false);        setCursor(Cursor.getPredefinedCursor(Cursor.WAIT_CURSOR));        //Instances of javax.swing.SwingWorker are not reusuable, so        //we create new instances as needed.        task = new Task();        task.addPropertyChangeListener(this);        task.execute();    }    /**     * Invoked when task's progress property changes.     */    public void propertyChange(PropertyChangeEvent evt) {        if ("progress" == evt.getPropertyName()) {            int progress = (Integer) evt.getNewValue();            progressBar.setValue(progress);            taskOutput.append(String.format(                    "Completed %d%% of task.\n", task.getProgress()));        }     }    /**     * Create the GUI and show it. As with all GUI code, this must run     * on the event-dispatching thread.     */    private static void createAndShowGUI() {        //Create and set up the window.        JFrame frame = new JFrame("ProgressBarDemo");        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);        //Create and set up the content pane.        JComponent newContentPane = new ProgressBarDemo();        newContentPane.setOpaque(true); //content panes must be opaque        frame.setContentPane(newContentPane);        //Display the window.        frame.pack();        frame.setVisible(true);    }    public static void main(String[] args) {        //Schedule a job for the event-dispatching thread:        //creating and showing this application's GUI.        javax.swing.SwingUtilities.invokeLater(new Runnable() {            public void run() {                createAndShowGUI();            }        });    }}