Mybatis关联关系

1.一对多关联关系

2. 多对多关联关系

首先最经典的案例体现一对多就是一个订单对应多个订单项
所以我们先用逆向生成工具生成订单表和订单项两张表的mapper和model
涉及表：t_hibernate_book、t_hibernate_book_category、t_hibernate_category

OrderVo

package com.liuxia.ssm.model.vo;import com.liuxia.ssm.model.Order;
import com.liuxia.ssm.model.OrderItem;import java.util.ArrayList;
import java.util.List;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.liuxia.ssm.model.vo;import com.liuxia.ssm.model.Order;
import com.liuxia.ssm.model.OrderItem;public class OrderItemVo extends OrderItem {private Order order;public Order getOrder() {return order;}public void setOrder(Order order) {this.order = order;}
}

然后再Mapper中写一个查询订单的方法

OrderMapper

package com.liuxia.ssm.mapper;import com.liuxia.ssm.model.Order;
import com.liuxia.ssm.model.vo.OrderVo;
import org.apache.ibatis.annotations.Param;import java.util.List;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);
}

然后在OrderMapper.xml中配置好一对多关联关系的映射

<?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.liuxia.ssm.mapper.OrderMapper" ><resultMap id="BaseResultMap" type="com.liuxia.ssm.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.liuxia.ssm.model.vo.OrderVo"><result property="orderId" column="order_id"></result><result property="orderNo" column="order_no"></result><!--<result property="orderItems"></result>--><collection property="orderItems" ofType="com.liuxia.ssm.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_orderwhere order_id = #{orderId,jdbcType=INTEGER}</select><delete id="deleteByPrimaryKey" parameterType="java.lang.Integer" >delete from t_hibernate_orderwhere order_id = #{orderId,jdbcType=INTEGER}</delete><insert id="insert" parameterType="com.liuxia.ssm.model.Order" >insert into t_hibernate_order (order_id, order_no)values (#{orderId,jdbcType=INTEGER}, #{orderNo,jdbcType=VARCHAR})</insert><insert id="insertSelective" parameterType="com.liuxia.ssm.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.liuxia.ssm.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.liuxia.ssm.model.Order" >update t_hibernate_orderset 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>

然后在OrderItemMapper.xml中配置好多个订单项对应一个订单的关系

<?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.liuxia.ssm.mapper.OrderItemMapper" ><resultMap id="BaseResultMap" type="com.liuxia.ssm.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.liuxia.ssm.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.liuxia.ssm.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_itemwhere order_item_id = #{orderItemId,jdbcType=INTEGER}</select><delete id="deleteByPrimaryKey" parameterType="java.lang.Integer" >delete from t_hibernate_order_itemwhere order_item_id = #{orderItemId,jdbcType=INTEGER}</delete><insert id="insert" parameterType="com.liuxia.ssm.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.liuxia.ssm.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.liuxia.ssm.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.liuxia.ssm.model.OrderItem" >update t_hibernate_order_itemset 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.oidand oi.order_item_id = #{orderItemId}</select>
</mapper>

OneToManyService

package com.liuxia.ssm.service;import com.liuxia.ssm.model.vo.OrderItemVo;
import com.liuxia.ssm.model.vo.OrderVo;import java.util.List;public interface OneToManyService {List<OrderVo> selectByOrderId(Integer orderId);List<OrderItemVo> selectByOrderItemId(Integer orderItemId);}

OneToManyServiceImpl

package com.liuxia.ssm.service.impl;import com.liuxia.ssm.mapper.OrderItemMapper;
import com.liuxia.ssm.mapper.OrderMapper;
import com.liuxia.ssm.model.vo.OrderItemVo;
import com.liuxia.ssm.model.vo.OrderVo;
import com.liuxia.ssm.service.OneToManyService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;import java.util.List;@Service
public class OneToManyServiceImpl implements OneToManyService {@Autowiredprivate OrderMapper orderMapper;@Autowiredprivate OrderItemMapper orderItemMapper;@Overridepublic List<OrderVo> selectByOrderId(Integer orderId) {return orderMapper.selectByOrderId(orderId);}@Overridepublic List<OrderItemVo> selectByOrderItemId(Integer orderItemId) {return orderItemMapper.selectByOrderItemId(orderItemId);}
}

OneToManyServiceImplTest

package com.liuxia.ssm.service.impl;import com.liuxia.ssm.model.OrderItem;
import com.liuxia.ssm.model.vo.OrderItemVo;
import com.liuxia.ssm.model.vo.OrderVo;
import com.liuxia.ssm.service.OneToManyService;
import com.liuxia.ssm.test.SpringJunitBaseTest;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;
import org.springframework.beans.factory.annotation.Autowired;import java.util.List;import static org.junit.Assert.*;public class OneToManyServiceImplTest extends SpringJunitBaseTest {@Autowiredprivate OneToManyService oneToManyService;@Beforepublic void setUp() throws Exception {}@Afterpublic void tearDown() throws Exception {}@Testpublic 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);}}@Testpublic void selectByOrderItemId() {List<OrderItemVo> orderItemVos = oneToManyService.selectByOrderItemId(36);OrderItemVo orderItemVo = orderItemVos.get(0);System.out.println(orderItemVo);System.out.println(orderItemVo.getOrder());}
}

然后可以看到查询出订单为8的订单并把它所有订单项也查出来了

多对多关联关系

我们多对多的配置和一对多是差不多的，多对多：多个一对多
这里是以一个书籍类别对应多本书，而一本书又对应多个书籍类别，通过一个中间表来实现多对多

涉及表：t_hibernate_book、t_hibernate_book_category、t_hibernate_category

HbookVo


package com.liuxia.ssm.model.vo;import com.liuxia.ssm.model.Category;
import com.liuxia.ssm.model.Hbook;import java.util.ArrayList;
import java.util.List;public class HbookVo extends Hbook {private List<Category> categories = new ArrayList();public List<Category> getCategories() {return categories;}public void setCategories(List<Category> categories) {this.categories = categories;}
}

CategoryVo

package com.liuxia.ssm.model.vo;import com.liuxia.ssm.model.Category;
import com.liuxia.ssm.model.Hbook;
import org.springframework.stereotype.Repository;import java.util.ArrayList;
import java.util.List;@Repository
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;}
}

中间表配置文件，HbookCategoryMapper.xml,基本配置都在里面了


<?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.liuxia.ssm.mapper.HbookCategoryMapper" ><resultMap id="BaseResultMap" type="com.liuxia.ssm.model.HbookCategory" ><constructor ><idArg column="bcid" jdbcType="INTEGER" javaType="java.lang.Integer" /><arg column="bid" jdbcType="INTEGER" javaType="java.lang.Integer" /><arg column="cid" jdbcType="INTEGER" javaType="java.lang.Integer" /></constructor></resultMap><sql id="Base_Column_List" >bcid, bid, cid</sql><select id="selectByPrimaryKey" resultMap="BaseResultMap" parameterType="java.lang.Integer" >select <include refid="Base_Column_List" />from t_hibernate_book_categorywhere bcid = #{bcid,jdbcType=INTEGER}</select><delete id="deleteByPrimaryKey" parameterType="java.lang.Integer" >delete from t_hibernate_book_categorywhere bcid = #{bcid,jdbcType=INTEGER}</delete><insert id="insert" parameterType="com.liuxia.ssm.model.HbookCategory" >insert into t_hibernate_book_category (bcid, bid, cid)values (#{bcid,jdbcType=INTEGER}, #{bid,jdbcType=INTEGER}, #{cid,jdbcType=INTEGER})</insert><insert id="insertSelective" parameterType="com.liuxia.ssm.model.HbookCategory" >insert into t_hibernate_book_category<trim prefix="(" suffix=")" suffixOverrides="," ><if test="bcid != null" >bcid,</if><if test="bid != null" >bid,</if><if test="cid != null" >cid,</if></trim><trim prefix="values (" suffix=")" suffixOverrides="," ><if test="bcid != null" >#{bcid,jdbcType=INTEGER},</if><if test="bid != null" >#{bid,jdbcType=INTEGER},</if><if test="cid != null" >#{cid,jdbcType=INTEGER},</if></trim></insert><update id="updateByPrimaryKeySelective" parameterType="com.liuxia.ssm.model.HbookCategory" >update t_hibernate_book_category<set ><if test="bid != null" >bid = #{bid,jdbcType=INTEGER},</if><if test="cid != null" >cid = #{cid,jdbcType=INTEGER},</if></set>where bcid = #{bcid,jdbcType=INTEGER}</update><update id="updateByPrimaryKey" parameterType="com.liuxia.ssm.model.HbookCategory" >update t_hibernate_book_categoryset bid = #{bid,jdbcType=INTEGER},cid = #{cid,jdbcType=INTEGER}where bcid = #{bcid,jdbcType=INTEGER}</update>
</mapper>

HbookCategoryMapper


package com.liuxia.ssm.mapper;import com.liuxia.ssm.model.HbookCategory;public interface HbookCategoryMapper {int deleteByPrimaryKey(Integer bcid);int insert(HbookCategory record);int insertSelective(HbookCategory record);HbookCategory selectByPrimaryKey(Integer bcid);int updateByPrimaryKeySelective(HbookCategory record);int updateByPrimaryKey(HbookCategory record);
}

ManyToManyServiceImplTest

package com.liuxia.ssm.service.impl;import com.liuxia.ssm.model.Category;
import com.liuxia.ssm.model.Hbook;
import com.liuxia.ssm.model.vo.CategoryVo;
import com.liuxia.ssm.model.vo.HbookVo;
import com.liuxia.ssm.service.ManyToManyService;
import com.liuxia.ssm.test.SpringJunitBaseTest;
import org.junit.Test;
import org.springframework.beans.factory.annotation.Autowired;import static org.junit.Assert.*;public class ManyToManyServiceImplTest extends SpringJunitBaseTest {@Autowiredprivate ManyToManyService manyToManyService;@Testpublic void selectByBid() {HbookVo hbookVo = manyToManyService.selectByBid(8);System.out.println(hbookVo);for (Category category : hbookVo.getCategories()) {System.out.println(category);}}@Testpublic void selectByCid() {CategoryVo categoryVo = this.manyToManyService.selectByCid(8);System.out.println(categoryVo);for (Hbook hbook : categoryVo.getHbooks()) {System.out.println(hbook);}}
}

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