使用HutoolUtil工具包之树结构工具TreeUtil 快速处理数据树形结构数据，很好很强大！
【摘要】 数据准备
CREATE TABLE `content_file_category` ( `id` bigint(20) NOT NULL AUTO_INCREMENT, `name` varchar(255) DEFAULT NULL COMMENT '名称', `parent_id` bigint(20) DEFAULT NULL COMMENT '所属分类', ...
数据准备
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CREATE TABLE `content_file_category` (
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`id` bigint(20) NOT NULL AUTO_INCREMENT,
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`name` varchar(255) DEFAULT NULL COMMENT '名称',
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`parent_id` bigint(20) DEFAULT NULL COMMENT '所属分类',
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`order_num` int(11) DEFAULT NULL COMMENT '排序序号',
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`level` int(11) DEFAULT NULL COMMENT '第几分类，从1开始',
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`gmt_create` datetime DEFAULT CURRENT_TIMESTAMP COMMENT '创建时间',
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`gmt_modify` datetime DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP COMMENT '最近更新时间',
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PRIMARY KEY (`id`),
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KEY `level_idx` (`level`),
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KEY `parent_id_idx` (`parent_id`),
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KEY `name_idx` (`name`)
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) ENGINE=InnoDB AUTO_INCREMENT=68 DEFAULT CHARSET=utf8 COMMENT='文件分类管理'
方案一：
一般情况下，我们自己写递归代码的方式
(1)获取树形结构数据接口
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/**
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* 获取文件分类树形结构
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*
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* @return
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*/
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@Override
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public FileCategoryListResponse queryFileCategoryTree(Integer levelDeep) {
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//查询一级分类
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List<FileCategoryDO> fileCategoryLevel1 = this.list(new LambdaQueryWrapper<FileCategoryDO>()
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.eq(FileCategoryDO::getLevel, FileCategoryLevelEnum.LEVEL_1.getCode())
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.orderByAsc(FileCategoryDO::getSort));
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//最终响应实体
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FileCategoryListResponse response = new FileCategoryListResponse();
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List<FileCategoryResponse> fileCategoryResponseList = new ArrayList<FileCategoryResponse>();
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if (!CollectionUtils.isEmpty(fileCategoryLevel1)) {
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for (FileCategoryDO fileCategoryDO : fileCategoryLevel1) {
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FileCategoryResponse fileCategoryResponse = new FileCategoryResponse().setChildren(new ArrayList<>());
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BeanUtils.copyProperties(fileCategoryDO, fileCategoryResponse);
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//循环遍历一级分类并进行递归操作，组装子分类
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getChildrenFileCategory(fileCategoryResponse, levelDeep);
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fileCategoryResponseList.add(fileCategoryResponse);
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}
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}
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response.setList(fileCategoryResponseList);
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return response;
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}
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/**
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* 递归获取下层级的文件分类
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*
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* @param fileCategoryResponse
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*/
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private void getChildrenFileCategory(FileCategoryResponse fileCategoryResponse, Integer levelDeep) {
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//获取id
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if (fileCategoryResponse != null) {
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Long id = fileCategoryResponse.getId();
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List<FileCategoryDO> list = this.list(new LambdaQueryWrapper<FileCategoryDO>()
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.eq(FileCategoryDO::getPid, id).le(FileCategoryDO::getLevel, levelDeep)
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.orderByAsc(FileCategoryDO::getSort));
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if (!CollectionUtils.isEmpty(list)) {
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List<FileCategoryResponse> childrens = list.stream().map(x -> {
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FileCategoryResponse dto = new FileCategoryResponse().setChildren(new ArrayList<>());
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BeanUtils.copyProperties(x, dto);
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return dto;
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}).collect(Collectors.toList());
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fileCategoryResponse.getChildren().addAll(childrens);
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for (FileCategoryResponse categoryResponse : childrens) {
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getChildrenFileCategory(categoryResponse, levelDeep);
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}
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}
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}
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}
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（2）根据父级id 递归获取子节点id集合
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/**
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* 根据文件分类id获取最下级文件分类id
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*
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* @param id
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* @return
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*/
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@Override
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public List<Long> recurQueryCatehoryId(Long id) {
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List<FileCategoryResponse> categoryResponses = new CopyOnWriteArrayList<>();
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FileCategoryDO fileCategory = this.getById(id);
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if (ObjectUtil.isNull(fileCategory)) {
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return null;
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}
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FileCategoryResponse fileCategoryResponse = new FileCategoryResponse().setChildren(new ArrayList<>());
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BeanUtils.copyProperties(fileCategory, fileCategoryResponse);
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categoryResponses.add(fileCategoryResponse);
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//递归获取子节点
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getChildrenFileCategory(fileCategoryResponse, FileCategoryLevelEnum.LEVEL_3.getCode());
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//将子节点加入到list
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categoryResponses = joinChildrenCategoryId(fileCategoryResponse, categoryResponses);
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//获取当前文件分类的非1级分类id
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List<Long> idList = categoryResponses.stream().filter(x -> x.getLevel() != null && Integer.parseInt(x.getLevel()) > FileCategoryLevelEnum.LEVEL_1.getCode())
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.map(FileCategoryResponse::getId).collect(Collectors.toList());
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// //根据层级进行分组，key-》层级，value-》每层级的文件分类列表
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// Map<String, List<FileCategoryResponse>> collect = categoryResponses.stream().collect(
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// Collectors.groupingBy(FileCategoryResponse::getLevel));
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// //根据层级key进行倒序，找到key值最大的层级（即最下级分类）
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// List<Long> idList = collect.entrySet().stream().sorted((o1, o2) -> o2.getKey().compareTo(o1.getKey())).
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// map(x -> x.getValue().stream().map(FileCategoryResponse::getId).collect(Collectors.toList()))
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// .findFirst().orElseGet(ArrayList::new);
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return idList;
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}
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private List<FileCategoryResponse> joinChildrenCategoryId(FileCategoryResponse fileCategoryResponse, List<FileCategoryResponse> categoryResponses) {
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List<FileCategoryResponse> childrens = fileCategoryResponse.getChildren();
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if (!CollectionUtils.isEmpty(childrens)) {
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categoryResponses.addAll(childrens);
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for (FileCategoryResponse children : childrens) {
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joinChildrenCategoryId(children, categoryResponses);
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}
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}
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return categoryResponses;
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}
方案二：
使用 Hutool的 TreeUtil 工具类
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public static void main(String[] args) {
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//模拟的从数据库查询出来的数据
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List<FileCategoryDO> fileCategoryDOS = new ArrayList<>();
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// 构建node列表
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List<TreeNode<String>> nodeList = CollUtil.newArrayList();
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List<TreeNode<Long>> collect = fileCategoryDOS.stream().map(fileCategoryDO -> {
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Map<String, Object> map = new HashMap<>();
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map.put("level", "2");
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map.put("gmt_create", LocalDateTime.now());
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map.put("gmt_modifier", LocalDateTime.now());
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TreeNode<Long> treeNode = new TreeNode<Long>().setId(fileCategoryDO.getId())
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.setName(fileCategoryDO.getCategoryName())
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.setParentId(Long.parseLong(fileCategoryDO.getPid()))
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.setWeight(fileCategoryDO.getSort())
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.setExtra(map);
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return treeNode;
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}).collect(Collectors.toList());
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//配置
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TreeNodeConfig treeNodeConfig = new TreeNodeConfig();
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// 自定义属性名 都要默认值的
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treeNodeConfig.setWeightKey("orderNum");
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treeNodeConfig.setIdKey("id");
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treeNodeConfig.setChildrenKey("childrenNode");
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// 最大递归深度
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treeNodeConfig.setDeep(3);
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//转换器
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List<Tree<String>> treeNodes = TreeUtil.build(nodeList, "0", treeNodeConfig,
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(treeNode, tree) -> {
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tree.setId(treeNode.getId());
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tree.setParentId(treeNode.getParentId());
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tree.setWeight(treeNode.getWeight());
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tree.setName(treeNode.getName());
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// 扩展属性 ...
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tree.putExtra("level", treeNode.getExtra().getOrDefault("level", 2));
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tree.putExtra("gmt_create", treeNode.getExtra().getOrDefault("gmt_create", null));
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});
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System.out.println(JSON.toJSONString(treeNodes));
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}
文章来源: blog.csdn.net，作者：血煞风雨城2018，版权归原作者所有，如需转载，请联系作者。
原文链接：blog.csdn.net/qq_31905135/article/details/110952955
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