Linux上使用模态对话框时繁忙光标的Swing渲染问题

Question

关闭模式对话框后在应用程序框架的玻璃窗格上设置忙碌光标时，并不总是显示忙碌光标。有时它有效（第一次它通常总是有效），有时则无效。

更好的是，在打开对话框之前设置忙碌光标时。显示忙碌光标，但是当将鼠标移入对话框然后移出对话框时，忙碌光标不再显示。

请注意，我仅在 Linux 上观察到以下错误。在 Mac OS X 或 Windows 上，行为是确定性且一致的。

另一个提示，在代码示例的第一种情况下，当鼠标未进入对话框并且使用键盘选择 YES_OPTION 时，始终显示忙碌的鼠标光标。同样在这种情况下，玻璃板上的“请稍等...”标签也从未被涂上。

这里有一个 SSCCE 演示了这些错误：

import java.awt.event.*;
import javax.swing.*;

public class TestFrame extends JFrame {

private JPanel panel;
private JPanel glassPane;

public TestFrame() {
    final JButton button1 = new JButton(new AbstractAction("Start activity indicator after closing the dialog") {
        @Override
        public void actionPerformed(ActionEvent e) {
            doAction1();
        }
    });

    final JButton button2 = new JButton(new AbstractAction("Start activity indicator before opening the dialog") {
        @Override
        public void actionPerformed(ActionEvent e) {
            doAction2();
        }
    });

    panel = new JPanel();
    panel.add(button1);
    panel.add(button2);
    getContentPane().add(panel, BorderLayout.NORTH);

    glassPane = (JPanel) getGlassPane();
    glassPane.setLayout(new BorderLayout());
    glassPane.setCursor(Cursor.getPredefinedCursor(Cursor.WAIT_CURSOR));
    glassPane.add(new JLabel("Please Wait..."), BorderLayout.CENTER);

    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setSize(800, 600);
    setVisible(true);
}

public void doAction1() {
    System.out.println("IsStartingInEDT?: "+  SwingUtilities.isEventDispatchThread());
    final int response = JOptionPane.showConfirmDialog(this, "Click on the YES_OPTION, busy indicator must start (if it does, try again).");
    if (JOptionPane.YES_OPTION == response) {
        startActivity();
        for (int i = 0; i < 5; i++) {
            try {
                Thread.sleep(200);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        stopActivity();
    }
}

public void doAction2() {
    startActivity();
    System.out.println("IsStartingInEDT?: "+  SwingUtilities.isEventDispatchThread());
    final int response = JOptionPane.showConfirmDialog(this, "Move the mouse inside the dialog (me) and then outside, the busy indicator is not shown anymore");
    if (JOptionPane.YES_OPTION == response) {
        for (int i = 0; i < 5; i++) {
            try {
                Thread.sleep(200);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }
    stopActivity();
}

public void startActivity() {
    System.out.println("TestFrame.startActivity()");
    glassPane.setVisible(true);
}

public void stopActivity() {
    System.out.println("TestFrame.stopActivity()");
    glassPane.setVisible(false);
}

/**
 * @param args
 */
public static void main(String[] args) {
    new TestFrame();
}

}

目前我在 JavaBug 队列中没有发现任何相关问题。在打开新的之前我会进一步搜索。

我也已经阅读了以下文章，但它不是很方便，因为从非模态对话框制作一个好的模态对话框并不简单： http://www.javaspecialists.eu/archive/Issue065.html

任何人都可以提供一些帮助？ 预先感谢，皮埃尔

Answer 1

您在这里遇到一些线程问题。

IsStartingInEDT 是真的吗？

如果是，那么您做错了，因为：

• 您不应该在 UI 线程中休眠。这将停止屏幕更新。

如果不是，那么您就做错了，因为：

• 必须从 UI 线程调用 OptionPane.showConfirmDialog()。

你应该这样做：

public void doAction1() {
    if (!SwingUtilities.isEventDispatchThread())  {
         System.err.println("error, must be edt");
         return;
    }

    final int response = JOptionPane.showConfirmDialog(this, "Click on the YES_OPTION, busy indicator must start (if it does, try again).");

    if (JOptionPane.YES_OPTION == response) {
        startActivity();   // change glass panel in edt    

        // new thread for long standing task
        new Thread( new Runnable() { public void run() {    
           for (int i = 0; i < 5; i++) {
               try {
                   Thread.sleep(200);
               } catch (Exception e) {
                   e.printStackTrace();
               }
           }

           SwingUtilities.invokeAndWait(new Runnable(){ public void run() {
              // changing glass panel need edt
              stopActivity();
           });
        }).start();
    }
}

Answer 2

第一。通过使用 Tread.sleep(int) 肯定会阻止 EDT，所有问题都与 Swing 中的并发

2.nd 之所以有效，是因为 JOptionPane 的初始化创建了一个新的 EDT，

这里是关于 .... 的简单演示，请仅举个例子，并确保这是违反所有 Swing 规则，但通过在 EDT 期间使用 Tread.sleep(int) 演示了锁定和解锁 EDT

< img src="https://i.sstatic.net/Xubhb.png" alt="在此处输入图像描述">

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.*;

public class ShakeComponents1 {

    private JFrame frame = new JFrame();
    private final String items[] = {"One", "Two", "Three"};
    private Timer timer;
    private JPanel panel = new JPanel();
    private JPanel buttonPanel = new JPanel();
    private JButton button = new JButton("  Exit  ");
    private boolean repeats = true;
    private boolean runs = false;
    private Color clr[] = {Color.red, Color.blue, Color.magenta};
    private Insets initMargin;

    public static void main(String[] args) {

        SwingUtilities.invokeLater(new Runnable() {

            @Override
            public void run() {
                new ShakeComponents1().makeUI();
            }
        });
    }

    public void makeUI() {
        buttonPanel = new JPanel();
        buttonPanel.setBorder(new EmptyBorder(5, 5, 5, 5));
        buttonPanel.setLayout(new BorderLayout());
        button.setPreferredSize(new Dimension(100, 45));
        button.setForeground(Color.darkGray);
        button.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent event) {
                Runnable doRun = new Runnable() {

                    @Override
                    public void run() {
                        System.exit(0);
                    }
                };
                SwingUtilities.invokeLater(doRun);
            }
        });
        button.addMouseListener(new java.awt.event.MouseListener() {

            @Override
            public void mouseClicked(MouseEvent e) {
            }

            @Override
            public void mousePressed(MouseEvent e) {
            }

            @Override
            public void mouseReleased(MouseEvent e) {
            }

            @Override
            public void mouseEntered(MouseEvent e) {
                if (runs) {
                    SwingUtilities.invokeLater(new Runnable() {

                        @Override
                        public void run() {
                            runs = false;
                            timer.stop();
                            changePnlBorder(new EmptyBorder(5, 5, 5, 5));
                            changeBtnForegroung(Color.darkGray);
                        }
                    });
                }
            }

            @Override
            public void mouseExited(MouseEvent e) {
                if (!runs) {
                    timer.start();
                    runs = true;
                }
            }
        });
        buttonPanel.add(button);
        final Insets margin = button.getMargin();
        panel.add(buttonPanel);
        for (int i = 0; i < 2; i++) {
            JComboBox combo = new JComboBox(items);
            combo.setMinimumSize(new Dimension(50, 25));
            combo.setMaximumSize(new Dimension(150, 25));
            combo.setPreferredSize(new Dimension(100, 25));
            combo.addActionListener(new ShakeAction());
            panel.add(combo);
        }
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.add(panel);
        frame.pack();
        frame.setLocation(50, 50);
        frame.setVisible(true);
        timer = new Timer(500, new ShakeAction());
        timer.setRepeats(repeats);
        initMargin = button.getMargin();
    }

    private class ShakeAction extends AbstractAction {

        private static final long serialVersionUID = 1L;
        private int noColor = 0;
        private Border border;
        private int count = 0;

        @Override
        public void actionPerformed(ActionEvent e) {
            timer.start();
            if (count > 5) {
                new Thread(new Runnable() {

                    @Override
                    public void run() {
                        try {
                            Thread.sleep(500);
                            changeBtnForegroung(Color.darkGray);
                            Thread.sleep(500);
                            count = 0;
                            Thread.sleep(750);
                        } catch (Exception e) {
                            System.out.println(e);
                        }
                    }
                }).start();
            } else {
                new Thread(new Runnable() {

                    @Override
                    public void run() {
                        try {
                            runs = true;
                            if (noColor < 2) {
                                noColor++;
                                changeBtnForegroung(clr[noColor]);
                            } else {
                                noColor = 0;
                                changeBtnForegroung(clr[noColor]);
                            }
                            changeBtnMargin(new Insets(initMargin.top, initMargin.left + 10, initMargin.bottom, initMargin.right - 10));
                            border = new EmptyBorder(0, 5, 10, 5);
                            changePnlBorder(border);
                            Thread.sleep(100);
                            changeBtnMargin(new Insets(initMargin.top, initMargin.left - 10, initMargin.bottom, initMargin.right + 10));
                            border = new EmptyBorder(0, 0, 10, 10);
                            changePnlBorder(border);
                            Thread.sleep(100);
                            changeBtnMargin(new Insets(initMargin.top, initMargin.left + 10, initMargin.bottom, initMargin.right - 10));
                            border = new EmptyBorder(5, 10, 5, 0);
                            changePnlBorder(border);
                            Thread.sleep(100);
                            changeBtnMargin(new Insets(initMargin.top, initMargin.left - 10, initMargin.bottom, initMargin.right + 10));
                            border = new EmptyBorder(10, 10, 0, 0);
                            changePnlBorder(border);
                            Thread.sleep(100);
                            changeBtnMargin(new Insets(initMargin.top, initMargin.left, initMargin.bottom, initMargin.right));
                            border = new EmptyBorder(5, 5, 5, 5);
                            changePnlBorder(border);
                            Thread.sleep(100);
                            count++;
                        } catch (Exception e) {
                            System.out.println(e);
                        }
                    }
                }).start();
            }
        }
    }

    private void changePnlBorder(final Border b) {
        SwingUtilities.invokeLater(new Runnable() {

            @Override
            public void run() {
                buttonPanel.setBorder(b);
                buttonPanel.revalidate();
                buttonPanel.repaint();
            }
        });
    }

    private void changeBtnForegroung(final Color c) {
        SwingUtilities.invokeLater(new Runnable() {

            @Override
            public void run() {
                button.setForeground(c);
            }
        });
    }

    private void changeBtnMargin(final Insets margin) {
        SwingUtilities.invokeLater(new Runnable() {

            @Override
            public void run() {
                button.setMargin(margin);
            }
        });
    }
}

结论 ->您可以创建新的Thread作为包装到Runnable中的BackGroung任务，如果您想模拟LongRunning任务并使用Thread.sleep(int)，也许可以回答您的问题位于此处

确保正确的方法是使用 SwingWorker ， Thread.sleep(int) 也是如此