子父级菜单查询

1、表结构数据

2、实体类定义

public class ParentHMClassify {

    private Integer id;

    private String classifyName;

    private Integer parentId;

    private Integer sort;
    /**
     * 子集合
     */
    List<ParentHMClassify> childList;
}

3、查询方法

    @Autowired
    private HMClassifyMapperCustom classifyMapperCustom;

    @Test
    public void query() {
        // 查询 db
        List<ParentHMClassify> classifyList1 = classifyMapperCustom.getClassifyList1();
        // 存放根节点信息
        List<ParentHMClassify> rootList = new ArrayList<>();
        for (ParentHMClassify parent : classifyList1) {
            if (parent.getParentId() == 0) {
                // 添加根节点
                rootList.add(parent);
                // 找到根节点下面的子节点菜单
                findChilds(parent, classifyList1);
            }
        }
        System.out.println("result:" + JSONObject.toJSONString(rootList));
    }

    /**
     * 递归查询子节点
     *
     * @param root
     * @param list
     */
    public void findChilds(ParentHMClassify root, List<ParentHMClassify> list) {
        System.out.println("查找子节点...");
        List<ParentHMClassify> childList = new ArrayList<>();
        for (ParentHMClassify menu : list) {
            if (root.getId() == menu.getParentId()) {
                childList.add(menu);
            }
        }
        // 子节点不存在，就不需要在遍历子节点中的节点了 直接返回
        if (childList.size() == 0) return;
        // 设置父节点的子节点列表
        root.setChildList(childList);
        // 若子节点存在，接着递归调用该方法，查询子节点的子节点
        for (ParentHMClassify childs : childList) {
            findChilds(childs, list);
        }
    }

4、子父级菜单数据结构为：

[
    {
        "classifyName":"VIP相关模板",
        "id":4,
        "parentId":0,
        "sort":1
    },
    {
        "childList":[
            {
                "childList":[
                    {
                        "classifyName":"材料遗失声明模板",
                        "id":9,
                        "parentId":6,
                        "sort":1
                    },
                    {
                        "classifyName":"345345",
                        "id":36,
                        "parentId":6,
                        "sort":2
                    }
                ],
                "classifyName":"档案科",
                "id":6,
                "parentId":5,
                "sort":1
            },
            {
                "childList":[
                    {
                        "childList":[
                            {
                                "classifyName":"公正委托书模板",
                                "id":13,
                                "parentId":10,
                                "sort":1
                            },
                            {
                                "classifyName":"交房委托书",
                                "id":14,
                                "parentId":10,
                                "sort":2
                            },
                            {
                                "classifyName":"未到场补充协议",
                                "id":15,
                                "parentId":10,
                                "sort":3
                            },
                            {
                                "classifyName":"未到场授权委托书",
                                "id":16,
                                "parentId":10,
                                "sort":4
                            }
                        ],
                        "classifyName":"买卖材料模板",
                        "id":10,
                        "parentId":7,
                        "sort":1
                    },
                    {
                        "classifyName":"租赁材料模板",
                        "id":11,
                        "parentId":7,
                        "sort":2
                    }
                ],
                "classifyName":"签约部",
                "id":7,
                "parentId":5,
                "sort":2
            },
            {
                "childList":[
                    {
                        "classifyName":"收入证明模板",
                        "id":12,
                        "parentId":8,
                        "sort":1
                    }
                ],
                "classifyName":"贷款部",
                "id":8,
                "parentId":5,
                "sort":3
            }
        ],
        "classifyName":"交易服务中心",
        "id":5,
        "parentId":0,
        "sort":2
    },
    {
        "childList":[
            {
                "childList":[
                    {
                        "childList":[
                            {
                                "classifyName":"四级菜单",
                                "id":41,
                                "parentId":40,
                                "sort":1
                            }
                        ],
                        "classifyName":"三级菜单",
                        "id":40,
                        "parentId":39,
                        "sort":2
                    }
                ],
                "classifyName":"二级菜单",
                "id":39,
                "parentId":38,
                "sort":1
            },
            {
                "childList":[
                    {
                        "childList":[
                            {
                                "classifyName":"四级菜单-1",
                                "id":44,
                                "parentId":43,
                                "sort":1
                            }
                        ],
                        "classifyName":"三级菜单-1",
                        "id":43,
                        "parentId":42,
                        "sort":1
                    }
                ],
                "classifyName":"二级菜单-1",
                "id":42,
                "parentId":38,
                "sort":2
            }
        ],
        "classifyName":"一级菜单",
        "id":38,
        "parentId":0,
        "sort":3
    }
]

5、总结

先查询所有菜单集合数据，然后遍历菜单集合获取根节点集合，然后调用查询子节点方法并在子节点方法中进行递归查询。如果当前节点没有子节点，直接return 不需要在进行递归查询。相反如果当前节点有子节点则一直进行递归查询。