一、获取所有分类上下级信息

/*** 获取所有分类上下级信息*/
public R<List<ResearchTypeTreeVO>> getTypeTreeList(){//获取所有分类数据List<ResearchTypeVO> list = ibResearchTypeService.getSuperList(null);List<ResearchTypeTreeVO> researchTypeTreeVOList = null;if(CollectionUtil.isNotEmpty(list)){researchTypeTreeVOList = buildMenuTrees(list);}return R.data(researchTypeTreeVOList);
}

二、构建数据

 public static List<ResearchTypeTreeVO> buildMenuTrees(List<ResearchTypeVO> list) {if(CollectionUtils.isEmpty(list)){return new ArrayList<>();}Map<Long, ResearchTypeVO> researchTypeVOMap = list.stream().collect((Collectors.toMap(ResearchTypeVO::getId, item -> item, (o, n) -> o)));//上级数据List<ResearchTypeTreeVO> parentList = new ArrayList<>();List<ResearchTypeTreeVO> childList = new ArrayList<>();for (ResearchTypeVO vo : list) {long parentId = vo.getSuperId();ResearchTypeTreeVO option = new ResearchTypeTreeVO();option.setId(vo.getId());option.setSuperId(parentId);option.setSuperName(vo.getSuperName());option.setLabel(vo.getTypeName());option.setValue(vo.getTypeCode());// 尝试查找父菜单项，如果不存在则dictBiz是顶级菜单项ResearchTypeVO researchTypeVO = researchTypeVOMap.get(parentId);if(Objects.isNull(researchTypeVO)){parentList.add(option);}else {childList.add(option);}}//对查询出来的菜单进行整理 整理为树状sortMenu(parentList, childList);return parentList;
}

三、递归

private static void sortMenu(List<ResearchTypeTreeVO> parentList, List<ResearchTypeTreeVO> childMenus) {for (ResearchTypeTreeVO parent : parentList) {List<ResearchTypeTreeVO> children = childMenus.stream().filter(child -> child.getSuperId().equals(parent.getId()) ).collect(Collectors.toList());// 设置父节点的子节点列表parent.setChildren(children);// 如果子节点列表不为空，则递归地对子节点进行排序if (!children.isEmpty()) {sortMenu(children, childMenus);}}
}