Java 阻止 JComponent 的焦点

Question

我为我的应用程序制作了一个 GUI。 JFrame 有 2 个 JPanel，panel1 和 panel2。 panel1 就是这样，一个带有自定义绘画的 JPanel，每 5 毫秒重新绘画一次。

panel2 是我第一次尝试 CardLayout 实现:它包含 JPanels subPanel1 和 subPanel2。 subPanel1 包含一个 JComboBox 并添加到 panel2:panel2.add(subPanel1);。

subPanel2 有 .setLayout(new CardLayout()); 命令，我向其中添加了 3 个新的 JPanel，以及适当的 itemListener 等。当然我也添加了: panel2.add(subPanel2);

现在解决问题:关注 Java 中的组件。我了解 setFocusable(boolean) 和 requestFocus() 方法。但我无法让他们以任何合乎逻辑的方式行事。

首先，它们的根本问题是:当组合框获得焦点时，我根本无法取消它的焦点(尝试用光标单击任何地方)。

以下是我进行的实验:

1) 在整个应用程序中没有任何与焦点相关的代码，组合框都会从焦点开始，无论 panel1 和 panel2 以什么顺序添加到 JFrame。

2) 如果我设置 panel1.setFocusable(true); (在其构造函数中)，它将从焦点开始

3) 如果我设置了 panel1.setFocusable(false); 并且还请求焦点，它不会得到它。 (唯一按预期工作的东西)

4) 如果我将 panel2、subPanel1 或 subPanel2 单独或任意组合设置为不可聚焦，它们仍然可以接收焦点(组合框，即，它是唯一能够注册焦点的组件)。

5) 如果我将组合框设置为不可聚焦，我仍然可以使用框的 itemListener 在 CardLayout 中的卡片之间滚动，但焦点不会粘在它上面。事实上 panel1 仍然注册键盘输入

所以我真的对整个“焦点”的事情感到非常困惑。也许这不是我想象的那样？我想做的是完全阻止与 panel2 的所有交互，直到标志(每 5 毫秒评估一次)为真。我是否正确地假设与 JPanel 不同，JComboBox 自动具有 mousebuttonListener 以在单击时获得焦点？如果不是，那么如何完全禁用 JComboBox 和当前卡显示的所有组件？不可聚焦组件中的组件仍然可聚焦是正常行为吗？

Answer 1

我尝试了许多不同的方法来解决类似的问题。

遍历组件层次结构并禁用每个组件的问题在于，您会破坏任何上下文并规避对这些组件的管理。

基本上，如果重新启用容器时某些子组件需要保持禁用状态，那么您会突然陷入多个级别相互交织的职责的问题......

迄今为止我发现的最佳解决方案是简单地使用 JXLayer，它提供了“可锁定”层概念，允许您“锁定”单个容器，从而防止用户与其交互，例如...

这直接取自JXLayer演示代码...

/**
 * Copyright (c) 2006-2008, Alexander Potochkin
 * All rights reserved.
 */

package org.jdesktop.jxlayer.demo;

import com.jhlabs.image.BlurFilter;
import com.jhlabs.image.EmbossFilter;
import org.jdesktop.jxlayer.JXLayer;
import org.jdesktop.jxlayer.demo.util.LafMenu;
import org.jdesktop.jxlayer.plaf.effect.BufferedImageOpEffect;
import org.jdesktop.jxlayer.plaf.effect.LayerEffect;
import org.jdesktop.jxlayer.plaf.ext.LockableUI;
import org.jdesktop.swingx.painter.BusyPainter;

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.geom.Ellipse2D;

/**
 * A demo to show the abilities of the {@link LockableUI}.
 * 
 * @see BusyPainterUI  
 */
public class LockableDemo extends JFrame {
    private JXLayer<JComponent> layer;
    private LockableUI blurUI = 
            new LockableUI(new BufferedImageOpEffect(new BlurFilter()));
    private EnhancedLockableUI embossUI = 
            new EnhancedLockableUI(new BufferedImageOpEffect(new EmbossFilter()));
    private LockableUI busyPainterUI = new BusyPainterUI();

    private JCheckBoxMenuItem disablingItem =
            new JCheckBoxMenuItem(new AbstractAction("Lock the layer") {

                public void actionPerformed(ActionEvent e) {
                    blurItem.setEnabled(!disablingItem.isSelected());
                    embossItem.setEnabled(!disablingItem.isSelected());
                    busyPainterItem.setEnabled(!disablingItem.isSelected());

                    blurUI.setLocked(disablingItem.isSelected());
                    embossUI.setLocked(disablingItem.isSelected());
                    busyPainterUI.setLocked(disablingItem.isSelected());
                }
            });

    private JRadioButtonMenuItem blurItem = new JRadioButtonMenuItem("Blur effect");
    private JRadioButtonMenuItem embossItem = new JRadioButtonMenuItem("Unlock button");
    private JRadioButtonMenuItem busyPainterItem = new JRadioButtonMenuItem("BusyPainter");

    public LockableDemo() {
        super("Lockable layer demo");
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        JComponent view = createLayerPanel();
        layer = new JXLayer<JComponent>(view);

        layer.setUI(blurUI);
        add(layer);
        add(createToolPanel(), BorderLayout.EAST);
        setJMenuBar(createMenuBar());
        setSize(380, 300);
        setLocationRelativeTo(null);
    }

    public static void main(String[] args) throws Exception {
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                new LockableDemo().setVisible(true);
            }
        });
    }

    private JMenuBar createMenuBar() {
        JMenu menu = new JMenu("Menu");

        disablingItem.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_D, InputEvent.ALT_MASK));

        menu.add(disablingItem);
        menu.addSeparator();

        blurItem.setSelected(true);
        blurItem.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_1, InputEvent.ALT_MASK));
        menu.add(blurItem);

        embossItem.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_2, InputEvent.ALT_MASK));
        menu.add(embossItem);

        busyPainterItem.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_3, InputEvent.ALT_MASK));
        menu.add(busyPainterItem);

        ButtonGroup group = new ButtonGroup();
        group.add(blurItem);
        group.add(embossItem);
        group.add(busyPainterItem);

        ItemListener menuListener = new ItemListener() {
            public void itemStateChanged(ItemEvent e) {
                if (blurItem.isSelected()) {
                    layer.setUI(blurUI);
                } else if (embossItem.isSelected()) {
                    layer.setUI(embossUI);
                } else if (busyPainterItem.isSelected()) {
                    layer.setUI(busyPainterUI);
                }
            }
        };

        blurItem.addItemListener(menuListener);
        embossItem.addItemListener(menuListener);
        busyPainterItem.addItemListener(menuListener);

        embossUI.getUnlockButton().addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                disablingItem.doClick();
            }
        });

        JMenuBar bar = new JMenuBar();
        bar.add(menu);

        bar.add(new LafMenu());
        return bar;
    }

    private JComponent createLayerPanel() {
        JComponent panel = new JPanel();
        panel.add(new JCheckBox("JCheckBox"));
        panel.add(new JRadioButton("JRadioButton"));
        panel.add(new JTextField(15));
        JButton button = new JButton("Have a nice day");
        button.setMnemonic('H');
        button.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                JOptionPane.showMessageDialog(LockableDemo.this,
                        "actionPerformed");
            }
        });
        panel.add(button);
        panel.add(new JTextField(15));
        panel.add(new JCheckBox("JCheckBox"));
        panel.add(new JRadioButton("JRadioButton"));
        panel.add(new JTextField(15));
        panel.add(new JCheckBox("JCheckBox"));
        panel.add(new JRadioButton("JRadioButton"));
        panel.setBorder(BorderFactory.createEtchedBorder());
        return panel;
    }

    private JComponent createToolPanel() {
        JComponent box = Box.createVerticalBox();
        JCheckBox button = new JCheckBox(disablingItem.getText());
        button.setModel(disablingItem.getModel());
        box.add(Box.createGlue());
        box.add(button);
        box.add(Box.createGlue());
        JRadioButton blur = new JRadioButton(blurItem.getText());
        blur.setModel(blurItem.getModel());
        box.add(blur);
        JRadioButton emboss = new JRadioButton(embossItem.getText());
        emboss.setModel(embossItem.getModel());
        box.add(emboss);
        JRadioButton translucent = new JRadioButton(busyPainterItem.getText());
        translucent.setModel(busyPainterItem.getModel());
        box.add(translucent);
        box.add(Box.createGlue());
        return box;
    }


    /**
     * Subclass of the {@link LockableUI} which shows a button
     * that allows to unlock the {@link JXLayer} when it is locked  
     */
    public static class EnhancedLockableUI extends LockableUI {
        private JButton unlockButton = new JButton("Unlock");

        public EnhancedLockableUI(LayerEffect... lockedEffects) {
            super(lockedEffects);
            unlockButton.addActionListener(new ActionListener() {
                public void actionPerformed(ActionEvent e) {
                    setLocked(false);
                }
            });
            unlockButton.setVisible(false);
        }

        public AbstractButton getUnlockButton() {
            return unlockButton;
        }

        @Override
        @SuppressWarnings("unchecked")
        public void installUI(JComponent c) {
            super.installUI(c);
            JXLayer<JComponent> l = (JXLayer<JComponent>) c;
            l.getGlassPane().setLayout(new GridBagLayout());
            l.getGlassPane().add(unlockButton);
            unlockButton.setCursor(Cursor.getDefaultCursor());
        }

        @Override
        @SuppressWarnings("unchecked")
        public void uninstallUI(JComponent c) {
            super.uninstallUI(c);
            JXLayer<JComponent> l = (JXLayer<JComponent>) c;
            l.getGlassPane().setLayout(new FlowLayout());
            l.getGlassPane().remove(unlockButton);
        }

        public void setLocked(boolean isLocked) {
            super.setLocked(isLocked);
            unlockButton.setVisible(isLocked);
        }
    }

    /**
     * Subclass of the {@link LockableUI} which uses the {@link BusyPainterUI}
     * from the SwingX project to implement the "busy effect" 
     * when {@link JXLayer} is locked.  
     */
    public static class BusyPainterUI extends LockableUI 
            implements ActionListener {
        private BusyPainter busyPainter;
        private Timer timer;
        private int frameNumber;

        public BusyPainterUI() {
            busyPainter = new BusyPainter() {
                protected void doPaint(Graphics2D g, JComponent object,
                                       int width, int height) {
                    // centralize the effect
                    Rectangle r = getTrajectory().getBounds();
                    int tw = width - r.width - 2 * r.x;
                    int th = height - r.height - 2 * r.y;
                    g.translate(tw / 2, th / 2);
                    super.doPaint(g, object, width, height);
                }
            };
            busyPainter.setPointShape(new Ellipse2D.Double(0, 0, 20, 20));
            busyPainter.setTrajectory(new Ellipse2D.Double(0, 0, 100, 100));
            timer = new Timer(100, this);
        }

        @Override
        protected void paintLayer(Graphics2D g2, JXLayer<? extends JComponent> l) {
            super.paintLayer(g2, l);
            if (isLocked()) {
                busyPainter.paint(g2, l, l.getWidth(), l.getHeight());
            }
        }

        @Override
        public void setLocked(boolean isLocked) {
            super.setLocked(isLocked);
            if (isLocked) {
                timer.start();
            } else {
                timer.stop();
            }
        }

        // Change the frame for the busyPainter
        // and mark BusyPainterUI as dirty 
        public void actionPerformed(ActionEvent e) {
            frameNumber = (frameNumber + 1) % 8;
            busyPainter.setFrame(frameNumber);
            // this will repaint the layer
            setDirty(true);
        }
    }
}