CategoryController

    @GetMapping("/detail")public Result<Category> detail(Integer id){Category c = categoryService.findById(id);return Result.success(c);}

CategoryService

    //根据id查询分类信息Category findById(Integer id);

CategoryServiceImpl

    @Overridepublic Category findById(Integer id) {Category c = categoryMapper.findById(id);return c;}

CategoryMapper

    //根据id查询@Select("select * from category where id = #{id}")Category findById(Integer id);

完成：