java中树形菜单获取（map方式）

雨点打透心脏的1/2处 2023-10-03 10:13 20阅读 0赞

## 流程分析： ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzgxMTA1Nw_size_16_color_FFFFFF_t_70]

## 一：返回的树形对象 ##

@Data
    @Builder
    @AllArgsConstructor
    @NoArgsConstructor
    public class TreeVo {
        
        /**
         * 节点id
         */
        private int id;
        /**
         * 节点名称
         */
        private String name;
        /**
         * 父节点id
         */
        private int parent;
    
        /**
         * 子节点集合
         */
        private List<TreeVo> children;
    
        public static List<TreeVo> allTreeVoList() {
        
    
            List<TreeVo> list = new ArrayList<>();
    
            TreeVo heFeiTreeVo = TreeVo.builder().id(2).name("合肥市").parent(0).build();
            list.add(heFeiTreeVo);
            TreeVo bengBuTreeVo = TreeVo.builder().id(3).name("蚌埠市").parent(0).build();
            list.add(bengBuTreeVo);
            TreeVo wuHuTreeVo = TreeVo.builder().id(4).name("芜湖市").parent(0).build();
            list.add(wuHuTreeVo);
            TreeVo shuShanTreeVo = TreeVo.builder().id(5).name("蜀山区").parent(2).build();
            list.add(shuShanTreeVo);
            TreeVo yaoHaiTreeVo = TreeVo.builder().id(6).name("瑶海区").parent(2).build();
            list.add(yaoHaiTreeVo);
    
            TreeVo bengShanTreeVo = TreeVo.builder().id(7).name("蚌山区").parent(3).build();
            list.add(bengShanTreeVo);
            TreeVo huaiShangTreeVo = TreeVo.builder().id(8).name("淮上区").parent(3).build();
            list.add(huaiShangTreeVo);
    
            list.add(TreeVo.builder().id(9).name("镜湖区").parent(4).build());
    
            list.add(TreeVo.builder().id(10).name("鸠江区").parent(4).build());
    
    
            return list;
        }
    
    
    }

## 二：树形结构处理 ##

/**
         * @return ListResult<List < TreeVo>>
         * @Author WXL
         * @Description 获取树形结构，不论有几层树都支持
         * @Date 2021/7/15
         * @Param
         **/
        @GetMapping(value = "/getCommonWordsTree", consumes = {
        "application/json"})
        public ListResult<List<TreeVo>> getCommonWordsTree() {
        
            ListResult<List<TreeVo>> listListResult = new ListResult<>();
            try {
        
                
                List<TreeVo> list = TreeVo.allTreeVoList();
                if (!CollectionUtils.isEmpty(list)) {
        
    
                    //1、将根节点放入临时List中
                    List<TreeVo> tempList = list.stream().filter(vo -> vo.getParent() == 0).collect(Collectors.toList());
    
                    //2、将所有数据放入Treemap中,遍历所有节点
                    Map<Integer, TreeVo> treeVoMap = list.stream().collect(Collectors.toMap(TreeVo::getId, e -> e));
                    for (Map.Entry<Integer, TreeVo> integerTreeVoEntry : treeVoMap.entrySet()) {
        
                        //2.1获取当前节点
                        TreeVo treeVo = integerTreeVoEntry.getValue();
                        int parentId = treeVo.getParent();
                        //2.2获取当前节点的父节点
                        TreeVo treeVoParent = treeVoMap.get(parentId);
                        //跳过根节点
                        if (ObjectUtils.isEmpty(treeVoParent)) {
        
                            continue;
                        }
                        //2.3将当前节点放入父节点的Children集合中
                        if (ObjectUtils.isEmpty(treeVoParent.getChildren())) {
        
                            //2.3.1每新增一层，都要new ArrayList<>()
                            List<TreeVo> treeVoList = new ArrayList<>();
                            treeVoList.add(treeVo);
                            treeVoParent.setChildren(treeVoList);
                        } else {
        
                            //2.3.2同层之间，在一个list中新增
                            treeVoParent.getChildren().add(treeVo);
                        }
                    }
                    //3 最后返回tempList即可
                    String treeString = JSONObject.toJSONString(tempList);
                    System.out.println("treeString = " + treeString);
                    listListResult.setStatus(200);
                    listListResult.setData(tempList);
                    listListResult.setMessage("查询树形结构成功");
                }
    
                return listListResult;
            } catch (Exception e) {
        
                log.error(e.getMessage(), e);
                listListResult.setStatus(HttpStatus.INTERNAL_SERVER_ERROR.value());
                listListResult.setMessage("查询树形结构失败");
                return listListResult;
            }
        }

## 三、返回结果 ##

{
        
        "status": 200,
        "data": [
            {
        
                "id": 2,
                "name": "合肥市",
                "parent": 0,
                "children": [
                    {
        
                        "id": 5,
                        "name": "蜀山区",
                        "parent": 2,
                        "children": null
                    },
                    {
        
                        "id": 6,
                        "name": "瑶海区",
                        "parent": 2,
                        "children": null
                    }
                ]
            },
            {
        
                "id": 3,
                "name": "蚌埠市",
                "parent": 0,
                "children": [
                    {
        
                        "id": 7,
                        "name": "蚌山区",
                        "parent": 3,
                        "children": null
                    },
                    {
        
                        "id": 8,
                        "name": "淮上区",
                        "parent": 3,
                        "children": null
                    }
                ]
            },
            {
        
                "id": 4,
                "name": "芜湖市",
                "parent": 0,
                "children": [
                    {
        
                        "id": 9,
                        "name": "镜湖区",
                        "parent": 4,
                        "children": null
                    },
                    {
        
                        "id": 10,
                        "name": "鸠江区",
                        "parent": 4,
                        "children": null
                    }
                ]
            }
        ],
        "message": "查询树形结构成功"
    }

## 四、代码demo ##

[github地址][github]

## 五、拓展 ##

[树型菜单获取][Link 1]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzgxMTA1Nw_size_16_color_FFFFFF_t_70]: https://img-blog.csdnimg.cn/20210716110522707.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzgxMTA1Nw==,size_16,color_FFFFFF,t_70
[github]: https://github.com/wxl52d41/GetTree.git
[Link 1]: https://blog.csdn.net/weixin_43811057/article/details/118468067