改变JPopupmenu行为

Question

我需要关于JTree和JPopupMenu的nimbus行为的帮助。我正在设置一个右键菜单到一个JTree。如果我在打开带有另一个节点的右键菜单后单击某个节点，单击的节点将被选中。但是在nimbus的外观和感觉中，选择另一个节点需要第二次单击。我的代码如下所示，您可以使用默认的外观来尝试它，并通过注释nimbus部分来感受它。

public class JTreeDemo {

    public static void main(String[] args) {

        try {
            for (LookAndFeelInfo info : UIManager.getInstalledLookAndFeels()) {
                if ("Nimbus".equals(info.getName())) {
                    UIManager.setLookAndFeel(info.getClassName());
                    break;
                }
            }
        } catch (Exception e) {
            try {
                UIManager.setLookAndFeel(UIManager.getCrossPlatformLookAndFeelClassName());
            } catch (Exception ex) {
            }
        }

        DefaultMutableTreeNode rootNode = new DefaultMutableTreeNode("Root");
        rootNode.add(new DefaultMutableTreeNode("Child1"));
        rootNode.add(new DefaultMutableTreeNode("Child2"));
        rootNode.add(new DefaultMutableTreeNode("Child3"));

        DefaultTreeModel model = new DefaultTreeModel(rootNode);

        JTree tree = new JTree(model);
        tree.addMouseListener(new TreeMouseListener());

        JFrame jf = new JFrame();
        jf.getContentPane().add(new JScrollPane(tree));

        jf.setSize(new Dimension(300, 300));

        jf.setVisible(true);
    }
}

class TreeMouseListener extends MouseAdapter {

    @Override
    public void mouseReleased(MouseEvent e) {
        if(SwingUtilities.isRightMouseButton(e)) {
            JTree tree = (JTree) e.getSource();

            TreePath jClickedPath = tree.getPathForLocation(e.getX(), e.getY());
            tree.setSelectionPath(jClickedPath);

            JPopupMenu menu = new JPopupMenu();
            menu.add(new JMenuItem("menu1"));
            menu.show(tree,  e.getX(), e.getY());
        }
    }
}

Answer 1

如果打印出按下的、释放的和单击的鼠标事件，您将看到默认的L&F。

// right click
tree: pressed
tree: released
tree: clicked
// click on node
tree: pressed
tree: released
tree: clicked

然而，在Nimbus L&F中，你可以得到

// right click
tree: pressed
tree: released
tree: clicked
// first click on node, the pressed event is not passed to the listener
tree: released
tree: clicked
// second click on node
tree: pressed
tree: released
tree: clicked

这是Nimbus弹出窗口在关闭时使用该事件所需的行为。(请参见错误报告#JDK-6770445中的解释)

您可以在设置L&F之后更改此行为。

UIManager.setLookAndFeel(info.getClassName());
UIManager.put("PopupMenu.consumeEventOnClose", false);

编辑片段，仅更改特定JTree的默认行为

// instruct the JTree not to close the popup
tree.putClientProperty("doNotCancelPopup",
    new JComboBox().getClientProperty("doNotCancelPopup"));

// create the popup menu not inside the listener
JPopupMenu popup = new JPopupMenu();
popup.add(new JMenuItem("menu1"));

// add the listener to the JTree
MouseListener popupListener = new PopupListener(popup);
tree.addMouseListener(popupListener);

以编程方式显示和隐藏弹出窗口

static class PopupListener extends MouseAdapter {

    JPopupMenu popup;

    PopupListener(JPopupMenu popupMenu) {
        popup = popupMenu;
    }

    @Override
    public void mousePressed(MouseEvent e) {
        togglePopup(e);
    }

    @Override
    public void mouseReleased(MouseEvent e) {
        togglePopup(e);
    }

    private void togglePopup(MouseEvent e) {
        if (e.isPopupTrigger()) {
            popup.show(e.getComponent(), e.getX(), e.getY());
        } else if (popup.isVisible()) {
            popup.setVisible(false);
        }
    }
}

Answer 2

有两种解决方案，您可以在不改变nimbus的情况下尝试：

1.模拟使用机器人类的第二次单击。

将这个添加到MouseListener中。

if(SwingUtilities.isLeftMouseButton(e) && e.getSource() instanceof JTree) {
            Robot bot = null;
            try {
                bot = new Robot();
            } catch (AWTException e1) {
                e1.printStackTrace();
            }
            bot.mousePress(InputEvent.BUTTON1_DOWN_MASK);
}

2.添加TreeSelectionLisitener，与第一种方法相同，使用MouseListener使用TreeSelectionListener选择合适的节点。