制作一个显示"请等待"JDialog的摇摆线程

Question

问题是这样的:
我正在运行一个swing应用程序,在某个时刻,对话框需要插入用户名和密码并按下"ok".
我希望当用户按下"ok"时,swing应用程序按此顺序执行:

1. 打开"请等待"JDialog
   
2. 进行一些操作(最终显示其他一些JDialog或JOptionPane)
   
3. 当它完成操作时关闭"请等待"JDialog
   

这是我在okButtonActionPerformed()中编写的代码:

private void okButtonActionPerformed(java.awt.event.ActionEvent evt) { 
    //This class simply extends a JDialog and contains an image and a jlabel (Please wait)
    final WaitDialog waitDialog = new WaitDialog(new javax.swing.JFrame(), false);    
    waitDialog.setVisible(true);
    ... //Do some operation (eventually show other JDialogs or JOptionPanes)
    waitDialog.dispose()
}

这段代码显然不起作用,因为当我在同一个线程中调用waitDialog时,它会阻塞所有代码直到我不关闭它.
所以我试着在另一个线程中运行它:

private void okButtonActionPerformed(java.awt.event.ActionEvent evt) { 
    //This class simply extends a JDialog and contains an image and a jlabel (Please wait)
    final WaitDialog waitDialog = new WaitDialog(new javax.swing.JFrame(), false);    
    SwingUtilities.invokeLater(new Runnable() {
        @Override
        public void run() {
            waitDialog.setVisible(true);
        }
    });
    ... //Do some operation (eventually show other JDialogs or JOptionPanes)
    waitDialog.dispose()
}

但这也不起作用,因为waitDialog不会立即显示,但只有在操作完成后才能完成工作(当他们显示joption窗格时"你以...身份登录")

我还尝试使用invokeAndWait而不是invokeLater,但在这种情况下它会抛出异常:

Exception in thread "AWT-EventQueue-0" java.lang.Error: Cannot call invokeAndWait from the event dispatcher thread

我能怎么做？

Answer 1

考虑使用SwingWorker进行后台工作,然后在SwingWorker done()方法中关闭对话框,或者在添加到SwingWorker的PropertyChangeListener中(我的偏好)关闭对话框.

例如,

import java.awt.BorderLayout;
import java.awt.Dialog.ModalityType;
import java.awt.Window;
import java.awt.event.ActionEvent;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;    
import javax.swing.*;

public class PleaseWaitEg {
   public static void main(String[] args) {
      JButton showWaitBtn = new JButton(new ShowWaitAction("Show Wait Dialog"));
      JPanel panel = new JPanel();
      panel.add(showWaitBtn);
      JFrame frame = new JFrame("Frame");
      frame.getContentPane().add(panel);
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.pack();
      frame.setLocationRelativeTo(null);
      frame.setVisible(true);

   }
}

class ShowWaitAction extends AbstractAction {
   protected static final long SLEEP_TIME = 3 * 1000;

   public ShowWaitAction(String name) {
      super(name);
   }

   @Override
   public void actionPerformed(ActionEvent evt) {
      SwingWorker<Void, Void> mySwingWorker = new SwingWorker<Void, Void>(){
         @Override
         protected Void doInBackground() throws Exception {

            // mimic some long-running process here...
            Thread.sleep(SLEEP_TIME);
            return null;
         }
      };

      Window win = SwingUtilities.getWindowAncestor((AbstractButton)evt.getSource());
      final JDialog dialog = new JDialog(win, "Dialog", ModalityType.APPLICATION_MODAL);

      mySwingWorker.addPropertyChangeListener(new PropertyChangeListener() {

         @Override
         public void propertyChange(PropertyChangeEvent evt) {
            if (evt.getPropertyName().equals("state")) {
               if (evt.getNewValue() == SwingWorker.StateValue.DONE) {
                  dialog.dispose();
               }
            }
         }
      });
      mySwingWorker.execute();

      JProgressBar progressBar = new JProgressBar();
      progressBar.setIndeterminate(true);
      JPanel panel = new JPanel(new BorderLayout());
      panel.add(progressBar, BorderLayout.CENTER);
      panel.add(new JLabel("Please wait......."), BorderLayout.PAGE_START);
      dialog.add(panel);
      dialog.pack();
      dialog.setLocationRelativeTo(win);
      dialog.setVisible(true);
   }
}

笔记:

• 一个关键的概念是设置所有内容,添加PropertyChangeListener,使SwingWorker运行,所有这些都在显示模式对话框之前,因为一旦显示模式对话框,所有来自调用代码的代码流都被冻结(如您所知) .
• 为什么我更喜欢PropertyChangeListener来使用done方法(正如Elias在这里得到的体面答案所示,我已经投票了) - 使用监听器提供了更多的关注点分离,更松散的耦合.这样,SwingWorker就不必知道正在使用它的GUI代码.

Answer 2

public void okButtonActionPerformed(ActionEvent e) {

    final JDialog loading = new JDialog(parentComponent);
    JPanel p1 = new JPanel(new BorderLayout());
    p1.add(new JLabel("Please wait..."), BorderLayout.CENTER);
    loading.setUndecorated(true);
    loading.getContentPane().add(p1);
    loading.pack();
    loading.setLocationRelativeTo(parentComponent);
    loading.setDefaultCloseOperation(JDialog.DO_NOTHING_ON_CLOSE);
    loading.setModal(true);

    SwingWorker<String, Void> worker = new SwingWorker<String, Void>() {
        @Override
        protected String doInBackground() throws InterruptedException 
            /** Execute some operation */   
        }
        @Override
        protected void done() {
            loading.dispose();
        }
    };
    worker.execute();
    loading.setVisible(true);
    try {
        worker.get();
    } catch (Exception e1) {
        e1.printStackTrace();
    }
}