Mybatis关联关系（一对多配置）-优快云博客

本文链接：https://blog.youkuaiyun.com/XiaoZJun/article/details/109435288

本文详细介绍了Mybatis中的一对多关系配置，包括实体类的VO设计、一对多关联关系的配置、SQL语句编写、Mapper接口及XML文件的实现，以及Service层和测试类的实现。通过示例代码展示了如何在OrderMapper和OrderItemMapper中设置一对多关系。

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Mybatis关联关系（一对多配置）

- 一对多

一对多

1.给两个实体类都定义一个vo类

package com.zhoujun.model.vo;

import com.zhoujun.model.Order;
import com.zhoujun.model.OrderItem;

import java.util.ArrayList;
import java.util.List;

/**
 * @author 小俊
 * @company 流弊公司董事长
 * @create  2020-10-28 16:01
 */
public class OrderVo extends Order {
    private List<OrderItem> orderItems=new ArrayList<>();

    public List<OrderItem> getOrderItems() {
        return orderItems;
    }

    public void setOrderItems(List<OrderItem> orderItems) {
        this.orderItems = orderItems;
    }
}

package com.zhoujun.model.vo;

import com.zhoujun.model.Order;
import com.zhoujun.model.OrderItem;

/**
 * @author 小俊
 * @company 流弊公司董事长
 * @create  2020-10-28 16:04
 */
public class OrderItemVo extends OrderItem {
    private Order order;

    public Order getOrder() {
        return order;
    }

    public void setOrder(Order order) {
        this.order = order;
    }
}

2.配对一对多关联关系

一的一方
在这里插入图片描述
sql语句

多的一方
在这里插入图片描述
sql语句

一方的源代码（OrderMapper.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.zhoujun.mapper.OrderMapper" >
  <resultMap id="BaseResultMap" type="com.zhoujun.model.Order" >
    <constructor >
      <idArg column="order_id" jdbcType="INTEGER" javaType="java.lang.Integer" />
      <arg column="order_no" jdbcType="VARCHAR" javaType="java.lang.String" />
    </constructor>
  </resultMap>

  <resultMap id="OrderVoMap" type="com.zhoujun.model.vo.OrderVo">
    <result property="orderId" column="order_id"></result>
    <result property="orderNo" column="order_no"></result>
<!--    <result property="orderItems" column="order_id"></result>-->
    <collection property="orderItems" ofType="com.zhoujun.model.OrderItem">
      <result property="orderItemId" column="order_item_id"></result>
      <result property="productId" column="product_id"></result>
      <result property="quantity" column="quantity"></result>
      <result property="oid" column="oid"></result>
    </collection>
  </resultMap>





  <sql id="Base_Column_List" >
    order_id, order_no
  </sql>
  <select id="selectByPrimaryKey" resultMap="BaseResultMap" parameterType="java.lang.Integer" >
    select 
    <include refid="Base_Column_List" />
    from t_hibernate_order
    where order_id = #{orderId,jdbcType=INTEGER}
  </select>
  <delete id="deleteByPrimaryKey" parameterType="java.lang.Integer" >
    delete from t_hibernate_order
    where order_id = #{orderId,jdbcType=INTEGER}
  </delete>
  <insert id="insert" parameterType="com.zhoujun.model.Order" >
    insert into t_hibernate_order (order_id, order_no)
    values (#{orderId,jdbcType=INTEGER}, #{orderNo,jdbcType=VARCHAR})
  </insert>
  <insert id="insertSelective" parameterType="com.zhoujun.model.Order" >
    insert into t_hibernate_order
    <trim prefix="(" suffix=")" suffixOverrides="," >
      <if test="orderId != null" >
        order_id,
      </if>
      <if test="orderNo != null" >
        order_no,
      </if>
    </trim>
    <trim prefix="values (" suffix=")" suffixOverrides="," >
      <if test="orderId != null" >
        #{orderId,jdbcType=INTEGER},
      </if>
      <if test="orderNo != null" >
        #{orderNo,jdbcType=VARCHAR},
      </if>
    </trim>
  </insert>
  <update id="updateByPrimaryKeySelective" parameterType="com.zhoujun.model.Order" >
    update t_hibernate_order
    <set >
      <if test="orderNo != null" >
        order_no = #{orderNo,jdbcType=VARCHAR},
      </if>
    </set>
    where order_id = #{orderId,jdbcType=INTEGER}
  </update>
  <update id="updateByPrimaryKey" parameterType="com.zhoujun.model.Order" >
    update t_hibernate_order
    set order_no = #{orderNo,jdbcType=VARCHAR}
    where order_id = #{orderId,jdbcType=INTEGER}
  </update>



  <select id="selectByOrderId" resultMap="OrderVoMap" parameterType="java.lang.Integer" >
 select *  from t_hibernate_order o,t_hibernate_order_item oi where o.order_id =oi.oid
and oi.oid= # {orderId}
  </select>
</mapper>

多的一方源代码（OrderItemMapper.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.zhoujun.mapper.OrderItemMapper" >
  <resultMap id="BaseResultMap" type="com.zhoujun.model.OrderItem" >
    <constructor >
      <idArg column="order_item_id" jdbcType="INTEGER" javaType="java.lang.Integer" />
      <arg column="product_id" jdbcType="INTEGER" javaType="java.lang.Integer" />
      <arg column="quantity" jdbcType="INTEGER" javaType="java.lang.Integer" />
      <arg column="oid" jdbcType="INTEGER" javaType="java.lang.Integer" />
    </constructor>
  </resultMap>


  <resultMap id="OrderItemVoMap" type="com.zhoujun.model.vo.OrderItemVo">

    <result property="orderItemId" column="order_item_id"></result>
    <result property="productId" column="product_id"></result>
    <result property="quantity" column="quantity"></result>
    <result property="oid" column="oid"></result>
    <!--    <result property="orderItems" column="order_id"></result>-->
    <association  property="order" javaType="com.zhoujun.model.Order">
      <result property="orderId" column="order_id"></result>
      <result property="orderNo" column="order_no"></result>
    </association>
  </resultMap>







  <sql id="Base_Column_List" >
    order_item_id, product_id, quantity, oid
  </sql>
  <select id="selectByPrimaryKey" resultMap="BaseResultMap" parameterType="java.lang.Integer" >
    select 
    <include refid="Base_Column_List" />
    from t_hibernate_order_item
    where order_item_id = #{orderItemId,jdbcType=INTEGER}
  </select>
  <delete id="deleteByPrimaryKey" parameterType="java.lang.Integer" >
    delete from t_hibernate_order_item
    where order_item_id = #{orderItemId,jdbcType=INTEGER}
  </delete>
  <insert id="insert" parameterType="com.zhoujun.model.OrderItem" >
    insert into t_hibernate_order_item (order_item_id, product_id, quantity, 
      oid)
    values (#{orderItemId,jdbcType=INTEGER}, #{productId,jdbcType=INTEGER}, #{quantity,jdbcType=INTEGER}, 
      #{oid,jdbcType=INTEGER})
  </insert>
  <insert id="insertSelective" parameterType="com.zhoujun.model.OrderItem" >
    insert into t_hibernate_order_item
    <trim prefix="(" suffix=")" suffixOverrides="," >
      <if test="orderItemId != null" >
        order_item_id,
      </if>
      <if test="productId != null" >
        product_id,
      </if>
      <if test="quantity != null" >
        quantity,
      </if>
      <if test="oid != null" >
        oid,
      </if>
    </trim>
    <trim prefix="values (" suffix=")" suffixOverrides="," >
      <if test="orderItemId != null" >
        #{orderItemId,jdbcType=INTEGER},
      </if>
      <if test="productId != null" >
        #{productId,jdbcType=INTEGER},
      </if>
      <if test="quantity != null" >
        #{quantity,jdbcType=INTEGER},
      </if>
      <if test="oid != null" >
        #{oid,jdbcType=INTEGER},
      </if>
    </trim>
  </insert>
  <update id="updateByPrimaryKeySelective" parameterType="com.zhoujun.model.OrderItem" >
    update t_hibernate_order_item
    <set >
      <if test="productId != null" >
        product_id = #{productId,jdbcType=INTEGER},
      </if>
      <if test="quantity != null" >
        quantity = #{quantity,jdbcType=INTEGER},
      </if>
      <if test="oid != null" >
        oid = #{oid,jdbcType=INTEGER},
      </if>
    </set>
    where order_item_id = #{orderItemId,jdbcType=INTEGER}
  </update>
  <update id="updateByPrimaryKey" parameterType="com.zhoujun.model.OrderItem" >
    update t_hibernate_order_item
    set product_id = #{productId,jdbcType=INTEGER},
      quantity = #{quantity,jdbcType=INTEGER},
      oid = #{oid,jdbcType=INTEGER}
    where order_item_id = #{orderItemId,jdbcType=INTEGER}
  </update>


  <select id="selectByOrderItemId" resultMap="OrderItemVoMap" parameterType="java.lang.Integer" >
 select *  from t_hibernate_order o,t_hibernate_order_item oi where o.order_id =oi.oid
and oi.order_item_id =#{orderItemId}
  </select>

</mapper>

3.OrderMapper接口类

package com.zhoujun.mapper;

import com.zhoujun.model.Order;
import com.zhoujun.model.vo.OrderVo;
import org.apache.ibatis.annotations.Param;
import org.springframework.stereotype.Repository;

import java.util.List;
@Repository
public interface OrderMapper {
    int deleteByPrimaryKey(Integer orderId);

    int insert(Order record);

    int insertSelective(Order record);

    Order selectByPrimaryKey(Integer orderId);

    int updateByPrimaryKeySelective(Order record);

    int updateByPrimaryKey(Order record);

    List<OrderVo> selectByOrderId(@Param("orderId") Integer orderId);

}

OrderItemMapper接口类

package com.zhoujun.mapper;

import com.zhoujun.model.OrderItem;
import com.zhoujun.model.vo.OrderItemVo;
import org.apache.ibatis.annotations.Param;
import org.springframework.stereotype.Repository;

import java.util.List;

@Repository
public interface OrderItemMapper {
    int deleteByPrimaryKey(Integer orderItemId);

    int insert(OrderItem record);

    int insertSelective(OrderItem record);

    OrderItem selectByPrimaryKey(Integer orderItemId);

    int updateByPrimaryKeySelective(OrderItem record);

    int updateByPrimaryKey(OrderItem record);

    List<OrderItemVo> selectByOrderItemId(@Param("orderItemId") Integer orderItemId);
}

4.service(实现类)

package com.zhoujun.service;

import com.zhoujun.model.vo.OrderItemVo;
import com.zhoujun.model.vo.OrderVo;
import org.apache.ibatis.annotations.Param;

import java.util.List;

/**
 * @author 小俊
 * @company 流弊公司董事长
 * @create  2020-10-30 10:11
 */
public interface OneToManyService {
    List<OrderVo> selectByOrderId(Integer orderId);
    List<OrderItemVo> selectByOrderItemId(Integer orderItemId);

}

servic(实现类)

package com.zhoujun.service.impl;

import com.zhoujun.mapper.OrderItemMapper;
import com.zhoujun.mapper.OrderMapper;
import com.zhoujun.model.vo.OrderItemVo;
import com.zhoujun.model.vo.OrderVo;
import com.zhoujun.service.OneToManyService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;

/**
 * @author 小俊
 * @company 流弊公司董事长
 * @create  2020-10-30 10:13
 */
@Service
public class OneToManyServiceImpl implements OneToManyService {
    @Autowired
    private OrderMapper orderMapper;
    @Autowired
    private OrderItemMapper orderItemMapper;
    @Override
    public List<OrderVo> selectByOrderId(Integer orderId) {
        return orderMapper.selectByOrderId(orderId);
    }

    @Override
    public List<OrderItemVo> selectByOrderItemId(Integer orderItemId) {

        return orderItemMapper.selectByOrderItemId(orderItemId);
    }
}

测试类

package com.zhoujun.service.impl;

import com.zhoujun.SpringBaseTest;
import com.zhoujun.model.OrderItem;
import com.zhoujun.model.vo.OrderItemVo;
import com.zhoujun.model.vo.OrderVo;
import com.zhoujun.service.OneToManyService;
import org.junit.Test;
import org.springframework.beans.factory.annotation.Autowired;

import java.util.List;

import static org.junit.Assert.*;

/**
 * @author 小俊
 * @company 流弊公司董事长
 * @create  2020-10-30 10:19
 */
public class OneToManyServiceImplTest extends SpringBaseTest {
    @Autowired
    private OneToManyService oneToManyService;

    @Test
    public void selectByOrderId() {
        List<OrderVo> orderVos =oneToManyService.selectByOrderId(8);
        OrderVo orderVo =orderVos.get(0);
        System.out.println(orderVo);
        for (OrderItem orderItem: orderVo.getOrderItems()){
            System.out.println(orderItem);
        }

    }

    @Test
    public void selectByOrderItemId() {
        List<OrderItemVo> orderItemVos=oneToManyService.selectByOrderItemId(36);
        OrderItemVo orderItemVo=orderItemVos.get(0);
        System.out.println(orderItemVo);
        System.out.println(orderItemVo.getOrder());
    }
}