谁用过swing进度条显示文件上传进度吗？
大家好，谁使用过swing的JProgressBar类设计过显示文件上传的进度条吗？并不要求度精确地显示，只要是能看出来开始，传出过程中和结束就行了。
[解决办法]
官方的例子
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(); } }); }}
[解决办法]
根据（文件的大小-上传的大小）/文件的大小，得到上传的百分比。通过把JProgressBar一个线程中通过setValue()显示进度.
可以通过ｆｉｌｅ．ｌｅｎｇ（）得到文件的大小，单位是字节。