zoukankan      html  css  js  c++  java
  • 根据根节点查询所有子节点

    package com.atguigu.gulimall.product.service.impl;
    
    import com.sun.org.apache.bcel.internal.generic.RETURN;
    import org.springframework.stereotype.Service;
    
    import java.util.List;
    import java.util.Map;
    import java.util.stream.Collectors;
    
    import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
    import com.baomidou.mybatisplus.core.metadata.IPage;
    import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
    import com.atguigu.common.utils.PageUtils;
    import com.atguigu.common.utils.Query;
    
    import com.atguigu.gulimall.product.dao.CategoryDao;
    import com.atguigu.gulimall.product.entity.CategoryEntity;
    import com.atguigu.gulimall.product.service.CategoryService;
    
    
    @Service("categoryService")
    public class CategoryServiceImpl extends ServiceImpl<CategoryDao, CategoryEntity> implements CategoryService {
    
        @Override
        public PageUtils queryPage(Map<String, Object> params) {
            IPage<CategoryEntity> page = this.page(
                    new Query<CategoryEntity>().getPage(params),
                    new QueryWrapper<CategoryEntity>()
            );
    
            return new PageUtils(page);
        }
    
        @Override
        public List<CategoryEntity> listWithTree() {
            List<CategoryEntity> entities = baseMapper.selectList(null);
            //找到所有一级分类
            List<CategoryEntity> level1Menus = entities.stream().filter((categoryEntity -> {
                return
                        categoryEntity.getParentCid() == 0;
            }
            )).map((menu)->{
                menu.setChildren(getChildrens(menu,entities));
                return menu;
            }).sorted((menu1,menu2)->{
                return menu1.getSort()-menu2.getSort();
            }).collect(Collectors.toList());
            return level1Menus;
        }
    
        //递归查找所有菜单的子菜单
        private List<CategoryEntity> getChildrens(CategoryEntity root,List<CategoryEntity> all){
            List<CategoryEntity> children = all.stream().filter((categoryEntity -> {
                return categoryEntity.getParentCid() == root.getCatId();
            })).map((categoryEntity -> {
                categoryEntity.setChildren(getChildrens(categoryEntity,all));
                return categoryEntity;
            })).sorted((menu1,menu2)->{
                return (menu1.getSort()==null?0:menu1.getSort())-(menu2.getSort()==null?0:menu2.getSort());
            }).collect(Collectors.toList());
            return children;
        }
    
    }
    

      

  • 相关阅读:
    一个例子帮助理解正则表达式
    requestAnimationFrame兼容性扩展
    检测访问网页的浏览器呈现引擎、平台、Windows操作系统、移动设备和游戏系统
    手把手教你如何安装和使用Karma-Jasmine
    cesium随笔 — 隐藏三维场景下方版权信息
    cesium随笔 — 获取当前鼠标的经度、纬度、高度
    Cesium Language (CZML) 入门2 — CZML Content(CZML的内容)
    html初识
    MySQL终章
    MySQL表与表之间的关系详解
  • 原文地址:https://www.cnblogs.com/vincentmax/p/14380907.html
Copyright © 2011-2022 走看看