Java之使用递归查询多级树形结构数据(多级菜单)，包括查询父级菜单

绝地灬酷狼 2024-03-23 13:35 81阅读 0赞

### 1:方法一：通过pid查询出全部pid下的菜单信息，包括父菜单 ###

@GetMapping("/menu")
        @ApiOperation(value = "树形查询", notes = "树形查询")
        public Result<?> findMenu(@RequestParam String pid) {
        
            List<DocCategoryManageVo> list = findMenu2(pid);
            List<String> strings = new ArrayList<>();
            List<String> menu2 = findMenu3(strings,list);
            return Result.OK(list);
        }
        
        public List<String> findMenu3(List<String> strings,List<DocCategoryManageVo> list) {
        
            for (DocCategoryManageVo docCategoryManageVo : list) {
        
                strings.add(docCategoryManageVo.getId());
                if (docCategoryManageVo.getChildMenu().size() > 0) {
        
                        findMenu3(strings,docCategoryManageVo.getChildMenu());
                }
            }
            return strings;
        }
    
    	public List<DocCategoryManageVo> findMenu2(String pid) {
        
            List<DocCategoryManageVo> listVo = new ArrayList<>();
            QueryWrapper queryWrapper = new QueryWrapper<>();
            //查询条件
            queryWrapper.eq("pid", pid);
            List<DocCategoryManage> list = docCategoryManageService.list(queryWrapper);
            for (DocCategoryManage doc : list) {
        
                DocCategoryManageVo docVo = new DocCategoryManageVo();
                // 赋值
                BeanUtils.copyProperties(doc, docVo);
                docVo.setTitle(doc.getName());
                docVo.setKey(doc.getId());
                docVo.setValue(doc.getId());
    //			 docVo.setChildren(new JSONArray());
                //递归子类数据
                docVo.setChildMenu(findMenu2(doc.getId()));
                listVo.add(docVo);
    
            }
            return listVo;
        }

### 2：方法二：通过pid查询出全部pid下的菜单信息，包括父菜单 ###

/**
         * 递归获取子节点ID
         * @param pid
         * @param ids
         */
        void pidLoop(String pid, List<String> ids) {
        
            // 记录ID编码
            ids.add(pid);
            List<DocCategoryManage> listByPid = getListByPid(pid);
            if(CollectionUtils.isEmpty(listByPid)) {
        
                return;
            } else {
        
                for(DocCategoryManage doc : listByPid) {
        
                    pidLoop(doc.getId(), ids);
                }
            }
        }

### 3：通过pid查询pid下的全部子菜单，不包括父菜单 ###

@GetMapping("/menu")
        @ApiOperation(value = "树形查询", notes = "树形查询")
        public Result<?> findMenu(@RequestParam String pid) {
        
            List<DocCategoryManageVo> list = findMenu2(pid);
            List<String> flatten = flatten(list);
            return Result.OK(list);
        }
    
    
    	public List<String> flatten(List<DocCategoryManageVo> list) {
        
            System.out.println("=======");
            return list.stream()
                    .flatMap(d -> d.getChildMenu().size() > 0 ? flatten(d.getChildMenu()).stream() : Stream.of(d.getId()))
                    .collect(Collectors.toList());
        }
    
    	
    	public List<DocCategoryManageVo> findMenu2(String pid) {
        
            List<DocCategoryManageVo> listVo = new ArrayList<>();
            QueryWrapper queryWrapper = new QueryWrapper<>();
            //查询条件
            queryWrapper.eq("pid", pid);
            List<DocCategoryManage> list = docCategoryManageService.list(queryWrapper);
            for (DocCategoryManage doc : list) {
        
                DocCategoryManageVo docVo = new DocCategoryManageVo();
                // 赋值
                BeanUtils.copyProperties(doc, docVo);
                docVo.setTitle(doc.getName());
                docVo.setKey(doc.getId());
                docVo.setValue(doc.getId());
    //			 docVo.setChildren(new JSONArray());
                //递归子类数据
                docVo.setChildMenu(findMenu2(doc.getId()));
                listVo.add(docVo);
    
            }
            return listVo;
        }