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

多对多

首先先用逆向生成工具生成t_hibernate_book、t_hibernate_book_category、t_hibernate_category，

这两张表对应的model与mapper

实体类

HbookVo 

package com.huang.model.vo;

import com.huang.model.Category;
import com.huang.model.Hbook;

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

/**
 * @auther 宇晨
 * @company
 * @create 2019-10-23-19:47
 */
public class HbookVo extends Hbook {
    private List<Category> categories=new ArrayList<>();
    
    public List<Category> getCategories(){
        return categories;
    }
    public void setcagegories(List<Category> categories){
        this.categories=categories;
    }
    
}

CategoryVo 

package com.huang.model.vo;

import com.huang.model.Category;
import com.huang.model.Hbook;

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

/**
 * @auther 宇晨
 * @company
 * @create 2019-10-23-20:04
 */
public class CategoryVo extends Category {
    private List<Hbook> hbooks=new ArrayList<>();

    public List<Hbook> getHbooks() {
        return hbooks;
    }

    public void setHbooks(List<Hbook> hbooks) {
        this.hbooks = hbooks;
    }
}

HbookMapper.xml

通过一个书籍类别id，查询出书籍的信息的同时，还查询出这本书对应的类别

<resultMap id="HbookVoMap" type="com.huang.model.vo.HbookVo">
    <result property="bookId" column="book_id"></result>
    <result property="bookName" column="book_name"></result>
    <result property="price" column="price"></result>
    <!--<result property="orderItems"></result>-->
    <collection property="categories" ofType="com.huang.model.Category">
      <result property="categoryId" column="category_id"></result>
      <result property="categoryName" column="category_name"></result>
    </collection>
  </resultMap>

 <select id="selectByBid" resultMap="HbookVoMap" parameterType="java.lang.Integer" >
   select * from t_hibernate_book b,t_hibernate_book_category bc,t_hibernate_category c where b.book_id=bc.bid and bc.cid=c.category_id and
   b.book_id=#{bid}
  </select>

HbookMapper.java

package com.huang.mapper;

import com.huang.model.Hbook;
import com.huang.model.vo.HbookVo;
import org.apache.ibatis.annotations.Param;
import org.springframework.stereotype.Repository;

@Repository
public interface HbookMapper {
    int deleteByPrimaryKey(Integer bookId);

    int insert(Hbook record);

    int insertSelective(Hbook record);

    Hbook selectByPrimaryKey(Integer bookId);

    int updateByPrimaryKeySelective(Hbook record);

    int updateByPrimaryKey(Hbook record);

    HbookVo selectByBid(@Param("bid") Integer bid);
}

CategoryMapper.xml

<resultMap id="CategoryVoMap" type="com.huang.model.vo.CategoryVo">
    <result property="categoryId" column="category_id"></result>
    <result property="categoryName" column="category_name"></result>
    <!--<result property="orderItems"></result>-->
    <collection property="hbooks" ofType="com.huang.model.Hbook">
      <result property="bookId" column="book_id"></result>
      <result property="bookName" column="book_name"></result>
      <result property="price" column="price"></result>
    </collection>
  </resultMap>

<!--通过一个类别id，查询出类别的信息的同时，还查询出这个类别对应的书籍-->
  <select id="selectByCid" resultMap="CategoryVoMap" parameterType="java.lang.Integer" >
   select * from t_hibernate_book b,t_hibernate_book_category bc,t_hibernate_category c where b.book_id=bc.bid and bc.cid=c.category_id and
   c.category_id=#{cid}
  </select>

CategoryMapper.java

package com.huang.mapper;

import com.huang.model.Category;
import com.huang.model.vo.CategoryVo;
import org.apache.ibatis.annotations.Param;
import org.springframework.stereotype.Repository;

@Repository
public interface CategoryMapper {
    int deleteByPrimaryKey(Integer categoryId);

    int insert(Category record);

    int insertSelective(Category record);

    Category selectByPrimaryKey(Integer categoryId);

    int updateByPrimaryKeySelective(Category record);

    int updateByPrimaryKey(Category record);

    CategoryVo selectByCid(@Param("cid") Integer cid);
}

ManyToManyService.java

package com.huang.service;

import com.huang.model.vo.CategoryVo;
import com.huang.model.vo.HbookVo;

/**
 * @auther 宇晨
 * @company
 * @create 2019-10-24-11:08
 */
public interface ManyToManyService {
    HbookVo selectByBid(Integer bid);
    CategoryVo selectByCid(Integer cid);
}

ManyToManyServiceImpl.java

package com.huang.service.impl;

import com.huang.mapper.CategoryMapper;
import com.huang.mapper.HbookMapper;
import com.huang.model.vo.CategoryVo;
import com.huang.model.vo.HbookVo;
import com.huang.service.ManyToManyService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

/**
 * @auther 宇晨
 * @company
 * @create 2019-10-24-11:11
 */
@Service
public class ManyToManyServiceImpl implements ManyToManyService {
    @Autowired
    private HbookMapper hbookMapper;
    @Autowired
    private CategoryMapper categoryMapper;
    @Override
    public HbookVo selectByBid(Integer bid) {
        return hbookMapper.selectByBid(bid);
    }

    @Override
    public CategoryVo selectByCid(Integer cid) {
        return categoryMapper.selectByCid(cid);
    }
}

测试
ManyToManyServiceImplTest.java

package com.huang.service.impl;

import com.huang.SpringBaseTest;
import com.huang.model.Category;
import com.huang.model.Hbook;
import com.huang.model.vo.CategoryVo;
import com.huang.model.vo.HbookVo;
import com.huang.service.ManyToManyService;
import org.junit.Test;
import org.springframework.beans.factory.annotation.Autowired;

/**
 * @auther 宇晨
 * @company
 * @create 2019-10-24-11:13
 */
public class ManyToManyServiceImplTest extends SpringBaseTest {

    @Autowired
    private ManyToManyService manyToManyService;
    @Test
    public void selectByBid() {
        HbookVo hbookVo=manyToManyService.selectByBid(8);
        System.out.println(hbookVo);
        for (Category category : hbookVo.getCategories()) {
            System.out.println(category);
        }
    }

    @Test
    public void selectByCid() {
        CategoryVo categoryVo = this.manyToManyService.selectByCid(8);
        System.out.println(categoryVo);
        for (Hbook hbook : categoryVo.getHbooks()) {
            System.out.println(hbook);
        }

    }
}

测试结果

selectByBid

selectByCid