创建具有子级的不可选择的 DefaultTreeModel 节点

Question

我有一个 DeafultTreeModel 树，其中包含三个级别的节点。我希望能够使根节点及其直接子节点不可选择。而第三级子节点应该是可选的。有人可以帮我解决这个问题。我是 Swing 的新手，希望有人能帮我解决这个问题，因为我无法在任何地方找到答案。

Answer 1

正如@MadProgrammer 所解释的，您需要提供自己的选择模型。一个基本策略是通过包装默认选择模型并将所有方法调用委托给它来实现选择模型，但是过滤您不想被选中的 TreePath。

这是一个小例子。它使用canPathBeAdded方法来过滤要选择的路径：

import java.beans.PropertyChangeListener;
import java.util.ArrayList;
import java.util.List;

import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTree;
import javax.swing.SwingUtilities;
import javax.swing.event.TreeSelectionListener;
import javax.swing.tree.DefaultMutableTreeNode;
import javax.swing.tree.DefaultTreeModel;
import javax.swing.tree.DefaultTreeSelectionModel;
import javax.swing.tree.RowMapper;
import javax.swing.tree.TreePath;
import javax.swing.tree.TreeSelectionModel;

public class TestTreeSelection {

    private class MyTreeSelectionModel implements TreeSelectionModel {

        TreeSelectionModel selectionModel = new DefaultTreeSelectionModel();

        private boolean canPathBeAdded(TreePath treePath) {
            return treePath.getPathCount() > 2;
        }

        private TreePath[] getFilteredPaths(TreePath[] paths) {
            List<TreePath> returnedPaths = new ArrayList<TreePath>(paths.length);
            for (TreePath treePath : paths) {
                if (canPathBeAdded(treePath)) {
                    returnedPaths.add(treePath);
                }
            }
            return returnedPaths.toArray(new TreePath[returnedPaths.size()]);
        }

        @Override
        public void setSelectionMode(int mode) {
            selectionModel.setSelectionMode(mode);
        }

        @Override
        public int getSelectionMode() {
            return selectionModel.getSelectionMode();
        }

        @Override
        public void setSelectionPath(TreePath path) {
            if (canPathBeAdded(path)) {
                selectionModel.setSelectionPath(path);
            }
        }

        @Override
        public void setSelectionPaths(TreePath[] paths) {
            paths = getFilteredPaths(paths);
            selectionModel.setSelectionPaths(paths);
        }

        @Override
        public void addSelectionPath(TreePath path) {
            if (canPathBeAdded(path)) {
                selectionModel.addSelectionPath(path);
            }
        }

        @Override
        public void addSelectionPaths(TreePath[] paths) {
            paths = getFilteredPaths(paths);
            selectionModel.addSelectionPaths(paths);
        }

        @Override
        public void removeSelectionPath(TreePath path) {
            selectionModel.removeSelectionPath(path);
        }

        @Override
        public void removeSelectionPaths(TreePath[] paths) {
            selectionModel.removeSelectionPaths(paths);
        }

        @Override
        public TreePath getSelectionPath() {
            return selectionModel.getSelectionPath();
        }

        @Override
        public TreePath[] getSelectionPaths() {
            return selectionModel.getSelectionPaths();
        }

        @Override
        public int getSelectionCount() {
            return selectionModel.getSelectionCount();
        }

        @Override
        public boolean isPathSelected(TreePath path) {
            return selectionModel.isPathSelected(path);
        }

        @Override
        public boolean isSelectionEmpty() {
            return selectionModel.isSelectionEmpty();
        }

        @Override
        public void clearSelection() {
            selectionModel.clearSelection();
        }

        @Override
        public void setRowMapper(RowMapper newMapper) {
            selectionModel.setRowMapper(newMapper);
        }

        @Override
        public RowMapper getRowMapper() {
            return selectionModel.getRowMapper();
        }

        @Override
        public int[] getSelectionRows() {
            return selectionModel.getSelectionRows();
        }

        @Override
        public int getMinSelectionRow() {
            return selectionModel.getMinSelectionRow();
        }

        @Override
        public int getMaxSelectionRow() {
            return selectionModel.getMaxSelectionRow();
        }

        @Override
        public boolean isRowSelected(int row) {
            return selectionModel.isRowSelected(row);
        }

        @Override
        public void resetRowSelection() {
            selectionModel.resetRowSelection();
        }

        @Override
        public int getLeadSelectionRow() {
            return selectionModel.getLeadSelectionRow();
        }

        @Override
        public TreePath getLeadSelectionPath() {
            return selectionModel.getLeadSelectionPath();
        }

        @Override
        public void addPropertyChangeListener(PropertyChangeListener listener) {
            selectionModel.addPropertyChangeListener(listener);
        }

        @Override
        public void removePropertyChangeListener(PropertyChangeListener listener) {
            selectionModel.removePropertyChangeListener(listener);
        }

        @Override
        public void addTreeSelectionListener(TreeSelectionListener x) {
            selectionModel.addTreeSelectionListener(x);
        }

        @Override
        public void removeTreeSelectionListener(TreeSelectionListener x) {
            selectionModel.removeTreeSelectionListener(x);
        }

    }

    protected void initUI() {
        final DefaultMutableTreeNode root = new DefaultMutableTreeNode("Root");
        fillTree(root, 5, "Some tree label");
        final DefaultTreeModel model = new DefaultTreeModel(root);
        JTree tree = new JTree(model);
        tree.setSelectionModel(new MyTreeSelectionModel());
        JFrame f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.add(new JScrollPane(tree));
        f.setSize(400, 600);
        f.setLocationRelativeTo(null);
        f.setVisible(true);
    }

    private void fillTree(DefaultMutableTreeNode parent, int level, String label) {
        for (int i = 0; i < 5; i++) {
            DefaultMutableTreeNode node = new DefaultMutableTreeNode(label + " " + i);
            parent.add(node);
            if (level > 0) {
                fillTree(node, level - 1, label);
            }
        }

    }

    public static void main(String[] args) {

        SwingUtilities.invokeLater(new Runnable() {

            @Override
            public void run() {
                new TestTreeSelection().initUI();
            }
        });
    }

}