How to show progress - Applet - Servlet

Question

Hi,
I am new to applet-servlet communication. I have to show the progress at the applet front-end using a JProgressBar for a task being done at the servlet end. I request the gurus on the forum to post any example code for the above situation.

Answer 1

Hi,
U will have to use the SwingWorker to popup the JProgressBar, but in here i dont think u will be getting any input from servlet giving the job completed, if u are using jdk1.4.1 u can use
setIndeterminate(true);
I am attaching 2 methods below which i use to display the JProgressBar
Method long task is where i actually call the servlet and in method buildData i create the URLConnection etc
//appletData must implement Serializable
public void buildData(Object appletData)throws Exception
//define servlet name here
ObjectInputStream inputFromServlet = null;
URL          studentDBservlet = new URL("MyServlet");
URLConnection servletConnection = studentDBservlet.openConnection();
servletConnection.setDoInput(true);
servletConnection.setDoOutput(true);
servletConnection.setUseCaches(false);
servletConnection.setRequestProperty("Content-Type", "application/octet-stream");
ObjectOutputStream outputToServlet =
          new ObjectOutputStream(servletConnection.getOutputStream());
     // serialize the object
     if (!SwingUtilities.isEventDispatchThread())
          outputToServlet.writeObject(input);
          outputToServlet.flush();
          outputToServlet.close();
          inputFromServlet = new ObjectInputStream(servletConnection.getInputStream());
     else
          inputFromServlet = longTask(servletConnection, outputToServlet, appletData);
private ObjectInputStream longTask(final URLConnection servletConnection,
                    final ObjectOutputStream outputToServlet,
                    final Object appletData)
     final JDialog dialog = new JDialog(PlanApplet.appletFrame, "Please Wait", true);
isProcess = true;
     MapsPanel panel = new MapsPanel();
     panel.setLayout(new BoxLayout(panel, BoxLayout.Y_AXIS));
     //MapsLabel label = new MapsLabel("Work in process....");
//label.setFont(Constant.bigFont);
     //label.setPreferredSize(new Dimension(230, 40));
     JProgressBar progressBar = new JProgressBar();
     progressBar.setIndeterminate(true);
     progressBar.setPreferredSize(new Dimension(140, 30));
// final JugglerLabel jugLabel = new JugglerLabel();
// jugLabel.startAnimation();
// panel.setPreferredSize(new Dimension(175, 175));
     MapsPanel progressPanel = new MapsPanel(new FlowLayout(FlowLayout.CENTER, 5, 5));
     progressPanel.setPreferredSize(new Dimension(140, 80));
progressPanel.add(progressBar);
//     progressPanel.add(jugLabel);
//     panel.add(Box.createVerticalStrut(5));
     //panel.add(label);
     panel.add(Box.createVerticalStrut(15));
     panel.add(progressPanel);
     panel.add(Box.createVerticalStrut(15));
     dialog.setSize(150, 115);
     dialog.setResizable(false);
//     dialog.getContentPane().add(jugLabel);
dialog.getContentPane().add(panel);
dialog.setDefaultCloseOperation(JDialog.DO_NOTHING_ON_CLOSE);
dialog.setLocation(ScreenSize.getDialogLocation(dialog));
//      final javax.swing.Timer popupTimer = new javax.swing.Timer(2000, new TimerListener(dialog));
     final SwingWorker worker = new SwingWorker()
     public Object construct()
          try
          PlanApplet.applet.setCursor(new Cursor(Cursor.WAIT_CURSOR));
          outputToServlet.writeObject(appletData);
          outputToServlet.flush();
          outputToServlet.close();
          return new ObjectInputStream(servletConnection.getInputStream());
          catch (Exception exc)
          return null;
     public void finished()
// jugLabel.stopAnimation();
          dialog.dispose();
Toolkit.getDefaultToolkit().beep();
isProcess = false;
          LogWriter.out("the long process is finished", LogWriter.BASIC);
     worker.start();
// popupTimer.start();
     //System.out.println("Process complete");
     dialog.show();
// while(isProcess)
     return (ObjectInputStream) worker.getValue();