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;

        }