JAVA查询树结构数据（省市区）使用hutool工具实现

    @PostMapping("/getTree")
    public Object getTree() {
        // 查询数据
        List<LxhpArea> areaList = areaService.list();
        // 构建的整个树数据
        List<TreeNode<String>> treeNodeList = areaList.stream().map(area -> {
            // 扩展字段赋值，下面要取这里的值
            Map<String, Object> extraMap = new HashMap<>();
            extraMap.put("domain", area.getDomain());
            extraMap.put("isOpen", area.getIsOpen());
            extraMap.put("bigArea", area.getBigArea());
            // 单个树数据构建
            TreeNode<String> treeNode = new TreeNode<String>()
                    .setId(String.valueOf(area.getId())) // 主键
                    .setParentId(String.valueOf(area.getReid())) // 父节点ID
                    .setName(area.getName()) // 省份名称
                    .setWeight(area.getSortOrder()) //权重，排序
                    .setExtra(extraMap); // 扩展字段
            return treeNode;
        }).collect(Collectors.toList());

        // 配置
        TreeNodeConfig treeNodeConfig = new TreeNodeConfig();
        // 自定义属性名（修改默认名称）
        treeNodeConfig.setWeightKey("sortOrder");
        treeNodeConfig.setChildrenKey("childrenNode");
        // 最大递归深度
        treeNodeConfig.setDeep(1);

        //转换器
        List<Tree<String>> treeNodes = TreeUtil.build(treeNodeList, "1", treeNodeConfig,
                (treeNode, tree) -> {
                    // 给树节点赋值（还能set 父 或子节点树）
                    tree.setId(treeNode.getId());
                    tree.setParentId(treeNode.getParentId());
                    tree.setWeight(treeNode.getWeight());
                    tree.setName(treeNode.getName());
                    // 扩展属性值赋值
                    // treeNode.getExtra().getOrDefault("domain", null) 是获取上面Map放进去的值，没有就是 null
                    tree.putExtra("domain", treeNode.getExtra().getOrDefault("domain", null));
                    tree.putExtra("isOpen", treeNode.getExtra().getOrDefault("isOpen", null));
                    tree.putExtra("bigArea", treeNode.getExtra().getOrDefault("bigArea", null));
                });
        return JSONUtil.parse(treeNodes);
    }

CREATE TABLE `lxhp_area` (
  `id` smallint(5) unsigned NOT NULL AUTO_INCREMENT,
  `reid` smallint(5) unsigned NOT NULL DEFAULT '0',
  `name` varchar(120) NOT NULL DEFAULT '',
  `sort_order` smallint(5) unsigned NOT NULL DEFAULT '0',
  `is_open` tinyint(3) unsigned NOT NULL DEFAULT '0',
  `domain` varchar(10) NOT NULL,
  `big_area` int(4) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=MyISAM AUTO_INCREMENT=3433 DEFAULT CHARSET=utf8;