java - 复合 JTree 节点允许事件传递到下面的对象

Question

我正在尝试创建一个 JTree，其中一些节点是包含 JLabel 和 JButton 的复合对象。节点代表 JLabel 显示的服务器和端口，JButton 将使用桌面 API 打开默认浏览器并转到 URL。

我已经阅读了以下内容，并尽可能地仔细阅读了它们。节点以我想要的方式显示(主要是 - 我可以稍后处理让它变得更好)但是当我尝试单击按钮时，JTree 正在响应事件，而不是按钮。

java swing: add custom graphical button to JTree item

http://www.java2s.com/Code/Java/Swing-JFC/TreeCellRenderer.htm

https://stackoverflow.com/a/3769158/1344282

我需要知道如何允许事件通过 JTree，以便它们由下面的对象(JButton 或 JLabel)处理。

这是我的 TreeCellEditor:

public class UrlValidationCellEditor extends DefaultTreeCellEditor
{
    public UrlValidationCellEditor(JTree tree, DefaultTreeCellRenderer renderer)
    {
        super(tree, renderer);
    }

    @Override
    public Component getTreeCellEditorComponent(JTree tree, Object value,
            boolean isSelected, boolean expanded, boolean leaf, int row)
    {
        return renderer.getTreeCellRendererComponent(tree, value, true, expanded, leaf, row, true);
    }

    @Override
    public boolean isCellEditable(EventObject anEvent)
    {
        return true; // Or make this conditional depending on the node
    }
}

这是 TreeCellRenderer:

public class UrlValidationRenderer extends DefaultTreeCellRenderer implements TreeCellRenderer
{
    JLabel titleLabel;
    UrlGoButton goButton;

    JPanel renderer;

    DefaultTreeCellRenderer defaultRenderer = new DefaultTreeCellRenderer();

    public UrlValidationRenderer()
    {
        renderer = new JPanel(new GridLayout(1, 2));
        titleLabel = new JLabel(" ");
        titleLabel.setForeground(Color.blue);
        renderer.add(titleLabel);
        goButton = new UrlGoButton();
        renderer.add(goButton);
        renderer.setBorder(BorderFactory.createLineBorder(Color.black));
        backgroundSelectionColor = defaultRenderer
            .getBackgroundSelectionColor();
        backgroundNonSelectionColor = defaultRenderer
            .getBackgroundNonSelectionColor();
    }

    @Override
    public Component getTreeCellRendererComponent(JTree tree, Object value,
      boolean selected, boolean expanded, boolean leaf, int row,
      boolean hasFocus)
    {
        Component returnValue = null;
        if ((value != null) && (value instanceof DefaultMutableTreeNode))
        {
          Object userObject = ((DefaultMutableTreeNode) value)
              .getUserObject();
          if (userObject instanceof UrlValidation)
          {
                UrlValidation validationResult = (UrlValidation) userObject;
                titleLabel.setText(validationResult.getServer()+":"+validationResult.getPort());
                goButton.setUrl(validationResult.getUrl());

                if (selected) {
                  renderer.setBackground(backgroundSelectionColor);
                } else {
                  renderer.setBackground(backgroundNonSelectionColor);
                }
                renderer.setEnabled(tree.isEnabled());
                returnValue = renderer;
          }
        }
        if (returnValue == null)
        {
          returnValue = defaultRenderer.getTreeCellRendererComponent(tree,
              value, selected, expanded, leaf, row, hasFocus);
        }
        return returnValue;
    }

}

如有任何见解或建议，我将不胜感激。谢谢!

Answer 1

渲染器不是这样工作的。它们用作橡皮图章，这意味着在绘制 JList 时，实际上只有一个渲染器实例被绘制到各处。因此它无法处理鼠标输入，因为对象并不真正存在 - 它们只是被绘制出来。

为了将鼠标事件传递给下面的对象，您需要实现一个单元格编辑器。有时，编辑器看起来与渲染器不同(例如，字符串渲染器是标签，编辑器是文本字段)。按照这个逻辑，必须使用组件的另一个实例来实现编辑器。

现在您将渲染按钮并使用它们进行操作(即编辑)。编辑器必须是 JButton 的另一个实例，与呈现器不同。将按钮作为渲染器实现很容易，但棘手的部分是作为编辑器实现。您需要扩展 AbstractCellEditor 并实现 TreeCellEditor 和 ActionListener。该按钮是编辑器类的一个字段。在编辑器类的构造函数中，您初始化按钮并添加this 作为按钮的新 Action 监听器。在 getTreeCellEditorComponent 方法中，您只需返回按钮。在 actionPerformed 中，您调用按钮按下时需要执行的任何代码 ，然后调用 stopCellEditing()。

这种方式适合我。

我制作了一个 SSCCE，演示了在字符串树上的用法

public class Start
{
    public static class ButtonCellEditor extends AbstractCellEditor implements TreeCellEditor, ActionListener, MouseListener
    {
        private JButton button;
        private JLabel label;
        private JPanel panel;
        private Object value;

        public ButtonCellEditor(){
            panel = new JPanel(new BorderLayout());
            button = new JButton("Press me!");
            button.addActionListener(this);
            label = new JLabel();
            label.addMouseListener(this);
            panel.add(button, BorderLayout.EAST);
            panel.add(label);
        }

        @Override public Object getCellEditorValue(){
            return value.toString();
        }

        @Override public void actionPerformed(ActionEvent e){
            String val = value.toString();
            System.out.println("Pressed: " + val);
            stopCellEditing();
        }

        @Override public Component getTreeCellEditorComponent(JTree tree, Object value, boolean isSelected, boolean expanded, boolean leaf, int row){
            this.value = value;
            label.setText(value.toString());
            return panel;
        }

        @Override public void mouseClicked(MouseEvent e){
        }

        @Override public void mousePressed(MouseEvent e){
            String val = value.toString();
            System.out.println("Clicked: " + val);
            stopCellEditing();
        }

        @Override public void mouseReleased(MouseEvent e){
        }

        @Override public void mouseEntered(MouseEvent e){
        }

        @Override public void mouseExited(MouseEvent e){
        }

    }

    public static class ButtonCellRenderer extends JPanel implements TreeCellRenderer
    {
        JButton button;
        JLabel label;

        ButtonCellRenderer(){
            super(new BorderLayout());
            button = new JButton("Press me!");
            label = new JLabel();
            add(button, BorderLayout.EAST);
            add(label);
        }

        @Override public Component getTreeCellRendererComponent(JTree tree, Object value, boolean selected, boolean expanded, boolean leaf, int row, boolean hasFocus){
            label.setText(value.toString());
            return this;
        }

    }

    public static void main(String[] args){
        JTree tree = new JTree();
        tree.setEditable(true);
        tree.setCellRenderer(new ButtonCellRenderer());
        tree.setCellEditor(new ButtonCellEditor());

        JFrame test = new JFrame();
        test.add(new JScrollPane(tree));
        test.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        test.setSize(500, 500);
        test.setLocationRelativeTo(null);
        test.setVisible(true);
    }
}