递归方法响应展示前端多级目录菜单（路由）权限功能

递归实现前端多层级路由

实现用户管理模块时，用户有不同角色和权限，根据用户所有的权限，实现前端多层级路由的实现，这里用循环嵌套调用方法，并封装了多个子级类，但当有更多子级时，就需要循环更多次，还要封装更多子级类，造成代码冗余。

@Data
public class OneMenu {
    private String id;
    private String title;
    private String icon;
    private String path;
    private String name;
    private List children;
}

@Data
public class TwoMenu {
    private String id;
    private String title;
    private String icon;
    private String path;
    private String name;
    
    //private List children;
}

        //2.1查询权限表数据
        //1.查询所有一级分类
        QueryWrapper wrapper = new QueryWrapper<>();
        wrapper.eq("pid", "0");
        List fatherList = sysPermissionService.list(wrapper);
        //2.查询所有二级分类
        QueryWrapper wrapper1 = new QueryWrapper<>();
        wrapper1.ne("pid", "0");
        List sonList = sysPermissionService.list(wrapper1);
        //创建list集合，用于封装最终封装数据
        List finalFatherList = new ArrayList<>();
        //封装一级分类
        for (SysPermission father : fatherList) {
            OneMenu oneMenu = new OneMenu();
            BeanUtils.copyProperties(father, oneMenu);
            finalFatherList.add(oneMenu);
            List finalSonList = new ArrayList<>();
            for (SysPermission son : sonList) {
                //判断二级分类pid和一级分类的id是否一样
                if (son.getPid().equals(father.getId())) {
                    TwoMenu twoMenu = new TwoMenu();
                    BeanUtils.copyProperties(son, twoMenu);
                    finalSonList.add(twoMenu);
                }
            }
            oneMenu.setChildren(finalSonList);
        }

在业务层新建一个getTree方法， 使用递归来实现子级路由的获得，组装权限目录树。在主业务层调用getTree方法，然后封装给响应对象响应给前端。

@Data
@NoArgsConstructor
@AllArgsConstructor
@Builder
public class PermissionRespNodeVo {
    
    private String id;
    
    private String title;
    
    private String icon;
    
    private String path;
    
    private String name;
    
    private List children;
}

@Data
@NoArgsConstructor
@AllArgsConstructor
@Builder
public class LoginRespVo {
    
    private String id;
    
    private String username;
    
    private String phone;
    
    private String nickName;
    
    private String realName;
    
    private Integer sex;
    
    private Integer status;
    
    private String email;
    
    private List menus;
    
    private List permissions;
}

    
    @Override
    public List getTree(List permissions, String pid, boolean isOnlyMenuType) {
        //构建权限树集合
        if (CollectionUtils.isEmpty(permissions)) {
            return null;
        }
        //组装权限树
        List infos = permissions.stream()
                .filter(p -> p.getPid().equals(pid) && (p.getType() != 3 || !isOnlyMenuType))
                .map(p -> {
                    PermissionRespNodeVo prnv = PermissionRespNodeVo.builder().id(p.getId()).title(p.getTitle())
                            .icon(p.getIcon()).path(p.getUrl()).name(p.getName())
                            //这里使用递归！！！
                            .children(getTree(permissions, p.getId(), isOnlyMenuType))
                            .build();
                    return prnv;
                }).collect(Collectors.toList());
        return infos;
    }

最后将得到的数据封装好返回给前端

        //添加权限树和权限按钮集合
        //获取当前用户拥有的权限集合
        List permissions = sysPermissionService.getPermissionByUserId(userInfo.getId());
        //组装权限树 顶级权限的pid约定为0
        List tree = sysPermissionService.getTree(permissions, "0", true);
        //获取菜单按钮集合
        List authBtnPerms = permissions.stream().filter(p -> p.getType() == 3).map(SysPermission::getCode).collect(Collectors.toList());
        loginRespVo.setMenus(tree);
        loginRespVo.setPermissions(authBtnPerms);
        //5.组装响应对象来响应前端
        return R.ok(loginRespVo);