java返回树形结构

结果：

控制层：

@PostMapping("/menuTree")
public Result menuTree() {
    Result result;
    try {
        List<Map> list;
        //获取全部模块
        list = menuService.getTree();
        result = Result.success(list, "获取全部菜单列表成功");
    } catch (Exception e) {
        logger.error("获取全部菜单列表异常", e);
        result = Result.failure("获取全部菜单列表异常" );
    }
    return result;
}

 业务层：

@Override
public List<Map> getTree() {
    List<Map> moduleTreeList = menuMapper.moduleTree("0");
    if (moduleTreeList != null && !moduleTreeList.isEmpty()) {
        moduleTreeList.forEach(moduleTree -> {
            List<Map> moduleTrees = menuMapper.moduleTree((String) moduleTree.get("code"));
            if (moduleTrees != null && !moduleTrees.isEmpty()) {
                moduleTree.put("children", moduleTrees);
                if (moduleTrees != null && !moduleTrees.isEmpty()) {
                    moduleTrees.forEach(map -> {
                        List<Map> maps = menuMapper.moduleTree((String) map.get("code"));
                        if (maps != null && !maps.isEmpty()) {
                            map.put("children", maps);
                        }
                    });
                }
            }
        });
    }
    return moduleTreeList;
}

数据层：

List<Map> moduleTree(String parentCode);

sql语句：

<select id="moduleTree" resultType="map">
    select m.id, m.code, m.parent_code, m.name, m.type
    from menu m where m.parent_code = #{0}
    order by m.order_num desc
</select>

表结构：