对应的代码文件如下
src/main/java/com/imooc/bilibili/dao/DemoDao.java

package com.imooc.bilibili.dao;


import org.apache.ibatis.annotations.Mapper;

@Mapper
public interface DemoDao {

    public Long query(Long id);
}

src/main/java/com/imooc/bilibili/api/DemoApi.java

package com.imooc.bilibili.api;

import com.imooc.bilibili.service.DemoService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class DemoApi {

    @Autowired
    private DemoService demoService;

    @GetMapping("/query")
    public Long query(Long id){
        return demoService.query(id);
    }
}

src/main/java/com/imooc/bilibili/service/DemoService.java

package com.imooc.bilibili.service;

import com.imooc.bilibili.dao.DemoDao;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.Map;

@Service
public class DemoService {

    @Autowired
    private DemoDao demoDao;

    public Long query(Long id){
        return demoDao.query(id);
    }
}

感觉自己没有写错，或者是需要配置哪些文件吗？