查询mysql数据部分，部分数据查不出来.求救

Question

具体描述：有三级分类菜单，单独查询每级菜单分类都能查到，现在就是第三级分类的菜单有部分的分类查询不出来（navicat能查出来，java出不出来）。

这是单独查询的第三级分类，下面的红框部分用过二级分类查询不到（navicat能查出来）

private List<CategoryEntity> getChildrenList(CategoryEntity root,List<CategoryEntity> all){
    List<CategoryEntity> list = new ArrayList<CategoryEntity>();
    for (CategoryEntity categoryEntity:all) {
        if (categoryEntity.getParentCid() == root.getCatId()){
            list.add(categoryEntity);
        }
    }
    //这里是是使用匿名内部类来完成的
    Collections.sort(list, new Comparator<CategoryEntity>() {
        @Override
        public int compare(CategoryEntity o1, CategoryEntity o2) {
            //指定比较规则，按照首字母降序来排列
            return o2.getSort()-o1.getSort();
        }
    });
    return list;
}

@Override
public List<CategoryEntity> listCategory() {
    List<CategoryEntity> categoryEntityList = new ArrayList<>();
    List<CategoryEntity> scendCategoryEntityList = categoryList(2);
    List<CategoryEntity> thirdCategoryEntityList = categoryList(3);
    //1、查出所有分类
    List<CategoryEntity> entities = baseMapper.selectList(null);
    System.out.println("获取到的三级分类---》" + thirdCategoryEntityList);
    for (CategoryEntity categoryEntity:entities) {
        if (categoryEntity.getParentCid() == 0){//找到一级菜单
            List<CategoryEntity> scendChildrenList = getChildrenList(categoryEntity, scendCategoryEntityList);
            for (CategoryEntity scendChildre:scendChildrenList) {
                scendChildre.setChildren(getChildrenList(scendChildre,thirdCategoryEntityList));
            }
            categoryEntity.setChildren(scendChildrenList);
            categoryEntityList.add(categoryEntity);
        }
    }
    return categoryEntityList;
}

上面是一种方法

下面又是一种：

//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 -> {
        //1、找到子菜单
        categoryEntity.setChildren(getChildrens(categoryEntity,all));
        return categoryEntity;
    }).sorted((menu1,menu2)->{
        //2、菜单的排序
        return (menu1.getSort()==null?0:menu1.getSort()) - (menu2.getSort()==null?0:menu2.getSort());
    }).collect(Collectors.toList());
    return children;
}

@Override
public List<CategoryEntity> listWithTree() {
    //1、查出所有分类
    List<CategoryEntity> entities = baseMapper.selectList(null);
    //2、组装成父子的树形结构
    //找到所有的一级分类
    List<CategoryEntity> level1Menus = entities.stream().filter(categoryEntity ->
            categoryEntity.getParentCid() == 0
    ).map((menu)->{
        menu.setChildren(getChildrens(menu,entities));
        return menu;
    }).sorted((menu1,menu2)->{
        return (menu1.getSort()==null?0:menu1.getSort()) - (menu2.getSort()==null?0:menu2.getSort());
    }).collect(Collectors.toList());
    return level1Menus;
}

Answer 1

hao