树型结构是比较常规的分类思维方式，好的分类规则能事半功倍，比如文件目录、日常开发的代码，时序图是树型结构的另一种展示形式。这里介绍插件中JTree的基本结构。

JTree对象生成及配置

/**     * 配置树对象     *     * @param tree   this.tree = new JXTree();     * @param treePanel   treePanel = new JScrollPane(); 滑动对象     * @param rootVisible 是否展示根节点     */    public static void configTree(JTree tree, JScrollPane treePanel, boolean rootVisible) {        // tree 配置        DefaultTreeModel model = (DefaultTreeModel) tree.getModel();        model.setRoot(new DefaultMutableTreeNode());        // 渲染树节点对象        tree.setCellRenderer(new MTTreeCellRenderer());        // 根节点不展示        tree.setRootVisible(rootVisible);        // true 或 false 决策根节点左上角折号是否展示        tree.setShowsRootHandles(true);        treePanel.setViewportView(tree);        // 快速搜索        new TreeSpeedSearch(tree);        // 用于loading的关键配置        ComponentUtil.putClientProperty(tree, ANIMATION_IN_RENDERER_ALLOWED, true);        ComponentUtil.putClientProperty(tree, AUTO_EXPAND_ALLOWED, false);        ComponentUtil.putClientProperty(tree, SHRINK_LONG_RENDERER, true);    }

JTree事件包装

/**     * @param tree     * @param treeContext 树所属的对象，一般用于树操作时需要数据传递     */    public static void addTreeEvent(JTree tree, TreePanelMark treeContext) {        // 树节点被选中时        tree.addTreeSelectionListener(e -> {            DefaultMutableTreeNode mutableTreeNode = (DefaultMutableTreeNode) tree.getLastSelectedPathComponent();            if (null == mutableTreeNode || !(mutableTreeNode.getUserObject() instanceof MTTreeCell)) {                return;            }            ((MTTreeCell) mutableTreeNode.getUserObject()).treeSelectionListener(tree, mutableTreeNode, treeContext);        });        // 树节被点击，单击、双击        tree.addMouseListener(new MouseAdapter() {            @Override            public void mouseClicked(MouseEvent e) {                if (SwingUtilities.isLeftMouseButton(e)) {                    final int doubleClick = 2;                    if (e.getClickCount() >= doubleClick) {                        DefaultMutableTreeNode mutableTreeNode = (DefaultMutableTreeNode) tree.getLastSelectedPathComponent();                        if (null == mutableTreeNode || !(mutableTreeNode.getUserObject() instanceof MTTreeCell)) {                            return;                        }                        ((MTTreeCell) mutableTreeNode.getUserObject()).doubleClick(tree, mutableTreeNode, treeContext);                    }                }            }            /**             * 右键菜单             */            @Override            public void mouseReleased(MouseEvent e) {                if (SwingUtilities.isRightMouseButton(e)) {                    TreePath path = tree.getPathForLocation(e.getX(), e.getY());                    tree.setSelectionPath(path);                    DefaultMutableTreeNode mutableTreeNode = (DefaultMutableTreeNode) tree.getLastSelectedPathComponent();                    if (null == mutableTreeNode || !(mutableTreeNode.getUserObject() instanceof MTTreeCell)) {                        return;                    }                    ((MTTreeCell) mutableTreeNode.getUserObject()).rightClick(tree, mutableTreeNode, e, treeContext);                }            }        });        // 按回车键跳转到对应方法        tree.addKeyListener(new KeyAdapter() {            @Override            public void keyPressed(KeyEvent e) {                super.keyPressed(e);                if (e.getKeyCode() == KeyEvent.VK_ENTER) {                    DefaultMutableTreeNode mutableTreeNode = (DefaultMutableTreeNode) tree.getLastSelectedPathComponent();                    if (null == mutableTreeNode || !(mutableTreeNode.getUserObject() instanceof MTTreeCell)) {                        return;                    }                    ((MTTreeCell) mutableTreeNode.getUserObject()).keyEnter(tree, mutableTreeNode, treeContext);                }            }        });    }

JTree递归包装成树节点

一般是 一个 userObject 对应一个 DefaultMutableTreeNode，树型关系由 DefaultMutableTreeNode 来维护，后面删除、添加、上移、下移方便处理。

/**     * 渲染遍历树     *     * @param tree     * @param rootTreeCell     */    public static DefaultMutableTreeNode renderRepeaterTree(JTree tree, MTTreeCell rootTreeCell) {        if (null == rootTreeCell) {            return null;        }        DefaultMutableTreeNode root = new DefaultMutableTreeNode(rootTreeCell);        renderRepeaterTreeSub(rootTreeCell.subTreeCell(), root);        DefaultTreeModel model = (DefaultTreeModel) tree.getModel();        model.setRoot(root);        expandOrCollapAll(tree, new TreePath(tree.getModel().getRoot()), true);        return root;    }    /**     * 递归遍历数据结构生成树节点     *     * @param subTreeCells     * @param parentNode     */    public static void renderRepeaterTreeSub(List subTreeCells, DefaultMutableTreeNode parentNode) {        if (CollectionUtils.isEmpty(subTreeCells)) {            return;        }        for (MTTreeCell subTreeCell : subTreeCells) {            DefaultMutableTreeNode treeNode = new DefaultMutableTreeNode(subTreeCell);            parentNode.add(treeNode);            renderRepeaterTreeSub(subTreeCell.subTreeCell(), treeNode);        }    }

JTree展开、收起树节点

/**     * 展开tree视图     *     * @param parent treePath     * @param expand 是否展开     */    public static void expandOrCollapAll(@NotNull JTree tree, @NotNull TreePath parent, boolean expand) {        TreeNode node = (TreeNode) parent.getLastPathComponent();        if (node.getChildCount() >= 0) {            for (Enumeration<?> e = node.children(); e.hasMoreElements(); ) {                TreeNode n = (TreeNode) e.nextElement();                TreePath path = parent.pathByAddingChild(n);                expandOrCollapAll(tree, path, expand);            }        }        // 展开或收起必须自下而上进行        if (expand) {            tree.expandPath(parent);        } else {            tree.collapsePath(parent);        }    }

JTree重新加载

当子节点变化后需要重新加载已经变化的子节点

/**     * 重新加载     *     * @param jTree     * @param node 变化的子节点的父节点     */    public static void reload(JTree jTree, DefaultMutableTreeNode node) {        ((DefaultTreeModel) jTree.getModel()).reload(node);    }

JTree 渲染对象 Renderer

public class MTTreeCellRenderer extends ColoredTreeCellRenderer {    /**     * 渲染每个节点     *     * @param tree     * @param value     * @param selected     * @param expanded     * @param leaf     * @param row     * @param hasFocus     */    @Override    public void customizeCellRenderer(@NotNull JTree tree, Object value, boolean selected, boolean expanded, boolean leaf, int row, boolean hasFocus) {        Object obj = ((DefaultMutableTreeNode) value).getUserObject();        if (obj instanceof MTTreeCell) {            MTTreeCell node = (MTTreeCell) obj;            Icon loadingIcon = node.loadingIcon();            if (null != loadingIcon) {                setIcon(loadingIcon);            } else if (null != node.selfControlSelect()) {                if (node.selfControlSelect()) {                    setIcon(node.iconSelected());                } else {                    setIcon(node.iconUnselected());                }            } else {                if (selected) {                    if (null != node.iconSelected()) {                        setIcon(node.iconSelected());                    }                } else {                    if (null != node.iconUnselected()) {                        setIcon(node.iconUnselected());                    }                }            }            if (null == node.fontAttributes()) {                append(node.cellShow());            } else {                append(node.cellShow(), node.fontAttributes());            }        }    }}