
    private final CategoryCustomMapper categoryMapperCustom;
    @Override
    public List<Category> queryAllRootLevelCats() {
        Example categoryExample = new Example(Category.class);
        Example.Criteria categoryCriteria = categoryExample.createCriteria();
        categoryCriteria.andEqualTo("fatherId", 0);
        return categoryMapper.selectByExample(categoryExample);
    }

    /**
     * @param rootCatId father id