mybatis关联关系映射

一对多

首先先用逆向生成工具生成t_hibernate_order、t_hibernate_order_item

这两张表对应的model与mapper

实体类

OrderVo 

package com.huang.model.vo;

import com.huang.model.Order;
import com.huang.model.OrderItem;

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

/**
 * @auther 宇晨
 * @company
 * @create 2019-10-23-12:01
 */
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;
    }
}

OrderItemVo 

package com.huang.model.vo;

import com.huang.model.Order;
import com.huang.model.OrderItem;

/**
 * @auther 宇晨
 * @company
 * @create 2019-10-23-12:03
 */
public class OrderItemVo extends OrderItem {
    private Order order;

    public Order getOrder() {
        return order;
    }

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

OrderMapper.xml

通过一个订单id,查询出订单信息的同时，查询出所有的订单项

<!--配置一对多关联关系映射-->
<resultMap id="OrderVoMap" type="com.huang.model.vo.OrderVo">
    <result property="orderId" column="order_id"></result>
    <result property="orderNo" column="order_no"></result>
     <!-- 一对多的关系 -->
　　 <!-- property: 指的是集合属性的值, ofType：指的是集合中元素的类型 -->
    <collection property="orderItems" ofType="com.huang.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>

<!-- 一对多查询语句-->
<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>

OrderMapper.java

package com.huang.mapper;

import com.huang.model.Order;
import com.huang.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.xml

通过一个订单id项，查询出订单id项信息的同时，查询出所属订单

<resultMap id="OrderItemVoMap" type="com.huang.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"></result>-->
  <association property="order" javaType="com.huang.model.Order">
  <result property="orderId" column="order_id"></result>
  <result property="orderNo" column="order_no"></result>
  </association>
  </resultMap>

<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>

OrderItemMapper.java

package com.huang.mapper;

import com.huang.model.OrderItem;
import com.huang.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);
}

OneToManyService

package com.huang.service;

import com.huang.model.vo.OrderItemVo;
import com.huang.model.vo.OrderVo;

import java.util.List;

/**
 * @auther 宇晨
 * @company
 * @create 2019-10-23-18:19
 */
public interface OneToManyService {
    List<OrderVo> selectByOrderId(Integer orderId);
    List<OrderItemVo> selectByOrderItemId(Integer orderItemId);

}

OneToManyServiceImpl 

package com.huang.service.impl;

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

import java.util.List;

/**
 * @auther 宇晨
 * @company
 * @create 2019-10-23-18:38
 */
@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

OneToManyServiceImplTest 

package com.huang.service.impl;

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

import java.util.List;

/**
 * @auther 宇晨
 * @company
 * @create 2019-10-23-18:43
 */
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(orderVos);
        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());
    }
}

运行结果
selectByOrderId

selectByOrderItemId