场景：当添加一个菜品时，还需要记录菜品的口味信息，因此需要对菜品表（dish）和口味表（dish_flavor）同时进行插入操作。
两个表的字段：
代码思路：由DishController将前端的请求派发给相应的业务层(DishService)，业务层随后通过调用持久层（DishMapper，DishFlavorMapper）进行数据的增删改。
细节：
- 由于要操作两张表，所以需要在业务层的对应方法上添加@Transactional，保证该事务的原子性，见DishServiceImpl；
- 插入口味数据时，需要获取刚插入的dish_id值，通过设置useGeneratedKeys实现，见DishMapper.xml；
代码（由上至下）：
控制层：
DishController
package com.sky.controller.admin;
import com.sky.dto.DishDTO;
import com.sky.result.Result;
import com.sky.service.DishService;
import io.swagger.annotations.Api;
import io.swagger.annotations.ApiModel;
import io.swagger.annotations.ApiOperation;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;
/**
* ClassName: DishController
* PackageName: com.sky.controller.admin
* Description: 菜品管理
*
* @Author Xiyan Zhong
* @Create 2023/12/20 下午2:19
* @Version 1.0
*/
@RestController
@RequestMapping("/admin/dish")
@Api(tags = "菜品相关接口")
@Slf4j
public class DishController {
@Autowired
private DishService dishService;
/**
* 新增菜品
* @param dishDTO
* @return
*/
@PostMapping
@ApiOperation("新增菜品")
public Result save(@RequestBody DishDTO dishDTO){
log.info("新增菜品：{}",dishDTO);
dishService.saveWithFlavor(dishDTO);
return Result.success();
}
}
业务层：
DishService：
package com.sky.service;
import com.sky.dto.DishDTO;
/**
* ClassName: DishService
* PackageName: com.sky.service
* Description:
*
* @Author Xiyan Zhong
* @Create 2023/12/20 下午2:23
* @Version 1.0
*/
public interface DishService {
/**
* 新增菜品和对应的口味
* @param dishDTO
*/
public void saveWithFlavor(DishDTO dishDTO);
}
DishServiceImpl：
package com.sky.service.impl;
import com.sky.dto.DishDTO;
import com.sky.entity.Dish;
import com.sky.entity.DishFlavor;
import com.sky.mapper.DishFlavorMapper;
import com.sky.mapper.DishMapper;
import com.sky.service.DishService;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.BeanUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import java.util.List;
/**
* ClassName: DishServiceImpl
* PackageName: com.sky.service.impl
* Description:
*
* @Author Xiyan Zhong
* @Create 2023/12/20 下午2:25
* @Version 1.0
*/
@Service
@Slf4j
public class DishServiceImpl implements DishService {
@Autowired
private DishMapper dishMapper;
@Autowired
private DishFlavorMapper dishFlavorMapper;
/**
* 新增菜品和对应的口味
* @param dishDTO
*/
@Transactional // 操作多张表的时候，添加@Transactional注解，保证该事件是原子性的，要么全成功，要么全失败
@Override
public void saveWithFlavor(DishDTO dishDTO) {
Dish dish = new Dish();
// 在属性拷贝时，注意属性命名要保持一致
BeanUtils.copyProperties(dishDTO, dish);
// 向菜品表插入1条数据
dishMapper.insert(dish);
// 获取insert语句生成的主键值
Long dishId = dish.getId();
List<DishFlavor> flavors = dishDTO.getFlavors();
if(flavors != null && flavors.size() > 0){
//遍历flavors，为每个口味附上相关的dishId
flavors.forEach(dishFlavor -> {
dishFlavor.setDishId(dishId);
});
// 向口味表插入n条数据
dishFlavorMapper.insertBatch(flavors);
}
}
}
需要注意的是，为了保证@Transactional有效，需要在当前项目的入口类添加@EnableTransactionManagement，启动注解方式的事务管理，如：
package com.sky;
import lombok.extern.slf4j.Slf4j;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.transaction.annotation.EnableTransactionManagement;
@SpringBootApplication
@EnableTransactionManagement //开启注解方式的事务管理
@Slf4j
public class SkyApplication {
public static void main(String[] args) {
SpringApplication.run(SkyApplication.class, args);
log.info("server started");
}
}
持久层：
DishMapper 接口
package com.sky.mapper;
import com.sky.annotation.AutoFill;
import com.sky.entity.Dish;
import com.sky.enumeration.OperationType;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Select;
/**
* ClassName: DishMapper
* PackageName: com.sky.mapper
* Description:
*
* @Author Xiyan Zhong
* @Create 2023/12/15 下午2:52
* @Version 1.0
*/
@Mapper
public interface DishMapper {
/**
* 根据分类id查询菜品数量
* @param categoryId
* @return
*/
@Select("select count(id) from dish where category_id = ${categoryId}")
Integer countByCategoryId(Long categoryId);
/**
* 插入菜品数据
* @param dish
*/
@AutoFill(value = OperationType.INSERT)
void insert(Dish dish);
}
DishMapper.xml
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd" >
<mapper namespace="com.sky.mapper.DishMapper">
<!--设置useGeneratedKeys="true" 表示需要获得插入数据后生成的主键值，返回到keyProperty="id"，即Dish对象中的id属性-->
<insert id="insert" parameterType="Dish" useGeneratedKeys="true" keyProperty="id">
insert into dish (name, category_id, price, image, description, create_time, update_time, create_user, update_user, status)
values
(#{name}, #{categoryId}, #{price}, #{image}, #{description}, #{createTime}, #{updateTime}, #{createUser}, #{updateUser},
#{status})
</insert>
</mapper>
DishFlavorMapper 接口
package com.sky.mapper;
import com.sky.entity.DishFlavor;
import org.apache.ibatis.annotations.Mapper;
import java.util.List;
/**
* ClassName: DishFlavorMapper
* PackageName: com.sky.mapper
* Description:
*
* @Author Xiyan Zhong
* @Create 2023/12/20 下午2:42
* @Version 1.0
*/
@Mapper
public interface DishFlavorMapper {
/**
* 批量插入口味数据
* @param flavors
*/
void insertBatch(List<DishFlavor> flavors);
}
DishFlavorMapper.xml
遍历插入多条数据
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd" >
<mapper namespace="com.sky.mapper.DishFlavorMapper">
<!--通过遍历插入多条数据-->
<insert id="insertBatch" parameterType="DishFlavor">
insert into dish_flavor (dish_id, name, value)
values
<foreach collection="flavors" item="df" separator=",">
(#{df.dishId},#{df.name},#{df.value})
</foreach>
</insert>
</mapper>
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