SwingWorker和JProgressBar的问题

Question

我需要将任何图像转换为字节数组以满足加密要求。我使用JProgressBar监视转换进度，以防所选图像很大：File p= new File("C:\");BufferedImage oImg = ImageIO.read(p);ByteArrayOutputStream ba = new ByteArrayOutputStream();ImageIO.write(oImg, "jpg", ba);ba.flush();ProgressBar pb = new ProgressBar();Thread thread = new Thread(pb);thread.join();pb.fireTask(ba.toByteArray());我定义了一个ProgressBar使用SwingWorker如下的类：public class ProgressBar extends JPanel implements Runnable {    private JProgressBar progressBar;    private Task task;    private byte[] imgByteArray;    public void run() {        createGUI();    }    // Create the GUI    private void createGUI() {        JFrame frame = new JFrame("Converting...");        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);        JComponent newContentPane = new ProgressBar();        newContentPane.setOpaque(true);         frame.setContentPane(newContentPane);        JPanel panel = new JPanel();        progressBar = new JProgressBar(0, 100);        progressBar.setBounds(20, 22, 419, 20);        progressBar.setValue(0);        progressBar.setStringPainted(true);        panel.add(progressBar);        add(panel);        setBorder(BorderFactory.createEmptyBorder(20, 20, 20, 20));        frame.pack();        frame.setVisible(true);    }    /**     * Firing the Task     */    public void fireTask(byte[] imgArray) {        System.arraycopy(imgArray, 0, imgByteArray, 0, imgByteArray.length);        setCursor(Cursor.getPredefinedCursor(Cursor.WAIT_CURSOR));        task = new Task();        task.execute();    }    class Task extends SwingWorker<Void, Void> {        @Override        public Void doInBackground() {            for (int i=0; i<=imgByteArray.length; i++){                 progressBar.setValue(i);                 progressBar.repaint();                 try{                    Thread.sleep(50);                } catch (InterruptedException err){                }            }            return null;        }