使用ssm框架实现菜单列表管理

菜单列表：有父级框和子级框，需要将两者关系从数据库这两者是多对多的关系。所以需要从数据库将两者关系获取并封装成List。
1、controller层
直接调用service层方法

@ApiOperation("获取菜单")
    @GetMapping("findNodes")
    public Result findNodes() {
        List<SysMenu> list = sysMenuService.findNodes();
        return Result.ok(list);
    }

2、service层
需要实现的功能：将列表的父级子级关系从数据库中拿出来进行封装成要求的List形式。

service接口

public interface SysMenuService extends IService<SysMenu> {

    List<SysMenu> findNodes();
}

service实现类
调用mapper层数据接口查询到所有的数据。
取封装类的方法将数据封装成树形结构。

@Service
public class SysMenuServiceImpl extends ServiceImpl<SysMenuMapper, SysMenu> implements SysMenuService {

    @Override
    public List<SysMenu> findNodes() {

        // 查询数据
        List<SysMenu> SysMenuList = baseMapper.selectList(null);

        // 构建树形结构
        List<SysMenu> resultList = MenuHelper.buildTree(SysMenuList);
        return resultList;
    }
}

封装类代码：使用递归实现；
递归入口：循环找到最顶层父级id进入到递归过程中 ，找到属于它的子级目录进行封装
注意判空初始化

public class MenuHelper {
    public static List<SysMenu> buildTree(List<SysMenu> sysMenuList) {
        List<SysMenu> trees = new ArrayList<>();
        for (SysMenu sysMenu : sysMenuList) {
        // 递归入口
            if(sysMenu.getParentId().longValue() == 0) {
                trees.add(getChildren(sysMenu, sysMenuList));
            }
        }
        return trees;
    }

    public static SysMenu getChildren(SysMenu sysMenu, List<SysMenu> sysMenuList) {

        sysMenu.setChildren(new ArrayList<SysMenu>());
        for (SysMenu item : sysMenuList) {
        // 找到该父级所对应的自己列表进行加入
            if(sysMenu.getId() == item.getParentId()) {
                if (sysMenu.getChildren() == null) {
                    sysMenu.setChildren(new ArrayList<>());
                }
                sysMenu.getChildren().add(getChildren(item, sysMenuList));
            }
        }
        return sysMenu;
    }
}

运行结果
使用swargger进行测试 有父子级关系，成功！

"children": [
        {
          "id": 3,
          "createTime": "2021-05-31 18:05:37",
          "updateTime": "2022-06-09 09:22:47",
          "isDeleted": 0,
          "param": {},
          "parentId": 2,
          "name": "用户管理",
          "type": 1,
          "path": "sysUser",
          "component": "system/sysUser/list",
          "perms": "",
          "icon": "el-icon-s-custom",
          "sortValue": 1,
          "status": 1,
          "children": [
            {
              "id": 6,
              "createTime": "2021-05-31 18:05:37",
              "updateTime": "2022-06-09 09:22:38",
              "isDeleted": 0,
              "param": {},
              "parentId": 3,
              "name": "查看",
              "type": 2,
              "path": null,
              "component": null,
              "perms": "bnt.sysUser.list",
              "icon": null,
              "sortValue": 1,
              "status": 1,
              "children": [],
              "select": false
            },
            {
              "id": 7,
              "createTime": "2021-05-31 18:05:37",
              "updateTime": "2022-06-09 09:22:38",
              "isDeleted": 0,
              "param": {},
              "parentId": 3,
              "name": "添加",
              "type": 2,
              "path": null,
              "component": null,
              "perms": "bnt.sysUser.add",
              "icon": null,
              "sortValue": 1,
              "status": 1,
              "children": [],
              "select": false
            },
            {
              "id": 8,
              "createTime": "2021-05-31 18:05:37",
              "updateTime": "2022-06-09 09:22:38",
              "isDeleted": 0,
              "param": {},
              "parentId": 3,
              "name": "修改",
              "type": 2,
              "path": null,
              "component": null,
              "perms": "bnt.sysUser.update",
              "icon": null,
              "sortValue": 1,
              "status": 1,
              "children": [],
              "select": false
            },
            {
              "id": 9,
              "createTime": "2021-05-31 18:05:37",
              "updateTime": "2022-06-09 09:22:38",
              "isDeleted": 0,
              "param": {},
              "parentId": 3,
              "name": "删除",
              "type": 2,
              "path": null,
              "component": null,
              "perms": "bnt.sysUser.remove",
              "icon": null,
              "sortValue": 1,
              "status": 1,
              "children": [],
              "select": false
            },
            {
              "id": 18,
              "createTime": "2022-05-23 17:14:32",
              "updateTime": "2022-06-09 09:22:38",
              "isDeleted": 0,
              "param": {},
              "parentId": 3,
              "name": "分配角色",
              "type": 2,
              "path": null,
              "component": null,
              "perms": "bnt.sysUser.assignRole",
              "icon": null,
              "sortValue": 1,
              "status": 1,
              "children": [],
              "select": false
            }
          ],
          "select": false
        },
        {
          "id": 4,
          "createTime": "2021-05-31 18:05:37",
          "updateTime": "2022-06-09 09:37:18",
          "isDeleted": 0,
          "param": {},
          "parentId": 2,
          "name": "角色管理",
          "type": 1,
          "path": "sysRole",
          "component": "system/sysRole/list",
          "perms": "",
          "icon": "el-icon-user-solid",
          "sortValue": 2,
          "status": 1,
          "children": [
            {
              "id": 10,
              "createTime": "2021-05-31 18:05:37",
              "updateTime": "2022-06-09 09:22:38",
              "isDeleted": 0,
              "param": {},
              "parentId": 4,
              "name": "查看",
              "type": 2,
              "path": null,
              "component": null,
              "perms": "bnt.sysRole.list",
              "icon": null,
              "sortValue": 1,
              "status": 1,
              "children": [],
              "select": false
            },
            {
              "id": 11,
              "createTime": "2021-05-31 18:05:37",
              "updateTime": "2022-06-09 09:22:38",
              "isDeleted": 0,
              "param": {},
              "parentId": 4,
              "name": "添加",
              "type": 2,
              "path": null,
              "component": null,
              "perms": "bnt.sysRole.add",
              "icon": null,
              "sortValue": 1,
              "status": 1,
              "children": [],
              "select": false
            },