java - JTree TreeCellRenderer 在显示选择颜色时引发问题

Question

我正在使用下面这段代码:

 class CountryTreeCellRenderer implements TreeCellRenderer {
        private JLabel label;

        CountryTreeCellRenderer() {
            label = new JLabel();
        }

        public Component getTreeCellRendererComponent(JTree tree, Object value, boolean selected, boolean expanded, boolean leaf, int row, boolean hasFocus) {
            Object o = ((DefaultMutableTreeNode) value).getUserObject();
            if (o instanceof Country) {
                Country country = (Country) o;
                label.setIcon(new ImageIcon(country.getFlagIcon()));
                label.setText(country.getName());
            } else {
                label.setIcon(null);
                label.setText("" + value);
            }
            return label;
        }
    }

由于我正在传递/返回标签，因此在选择 JTree 中的任何组件时，不会出现选择颜色。我尝试使用:

JComponent comp = (JComponent) super.getTreeCellRendererComponent(tree, value, selected, expanded, leaf, row, hasFocus);
comp.setOpaque(true);
if(selected)
comp.setBackground(Color.RED);

但是如果我返回 comp，那么树的输出就不会按预期出现。

如何解决？

我没有为此实现任何编辑器。

Answer 1

请看source code of the DefaultTreeCellRenderer ，它也扩展了 JLabel 并且完全能够设置背景颜色。我复制粘贴了以下相关行:

  if (selected)
    {
      super.setBackground(getBackgroundSelectionColor());
      setForeground(getTextSelectionColor());

      if (hasFocus)
        setBorderSelectionColor(UIManager.getLookAndFeelDefaults().
                                getColor("Tree.selectionBorderColor"));
      else
        setBorderSelectionColor(null);
    }
  else
    {
      super.setBackground(getBackgroundNonSelectionColor());
      setForeground(getTextNonSelectionColor());
      setBorderSelectionColor(null);
    }