mybatis之关联关系 | 关联关系

前言：
在我们之前的hibernate中我们是学过了关联关系的，
所以我们在本章给讲一讲mybatis的关联关系。

mybatis的关联关系
一对多的测试
1.通过逆向工程生成Hbook,HbookCategory,Category
如何生成，可以参考之前的
这次我们要用到五张数据库表

<table schema="" tableName="t_hibernate_order" domainObjectName="Order"

               enableCountByExample="false" enableDeleteByExample="false"

               enableSelectByExample="false" enableUpdateByExample="false">

        </table>

        <table schema="" tableName="t_hibernate_order_item" domainObjectName="OrderItem"

               enableCountByExample="false" enableDeleteByExample="false"

               enableSelectByExample="false" enableUpdateByExample="false">

        </table>

        <table schema="" tableName="t_hibernate_book" domainObjectName="Hbook"

               enableCountByExample="false" enableDeleteByExample="false"

               enableSelectByExample="false" enableUpdateByExample="false">

        </table>

        <table schema="" tableName="t_hibernate_category" domainObjectName="Category"

               enableCountByExample="false" enableDeleteByExample="false"

               enableSelectByExample="false" enableUpdateByExample="false">

        </table>

        <table schema="" tableName="t_hibernate_book_category" domainObjectName="HbookCategory"

               enableCountByExample="false" enableDeleteByExample="false"

               enableSelectByExample="false" enableUpdateByExample="false">

        </table>

生成之后目录

mybatis之关联关系-LMLPHP

OrderVo

package com.jt.model.vo;

import com.jt.model.Orde;

import com.jt.model.OrdeItem;

import java.util.ArrayList;

import java.util.List;

/**

 * @author jt

 * @site www.xiaomage.com

 * @company xxx公司

 * @create  2019-10-23 18:59

 */

public class OrderVo extends Orde {

    private List<OrdeItem> orderItems=new ArrayList<>();

    public List<OrdeItem> getOrderItems() {

        return orderItems;

    }

    public void setOrderItems(List<OrdeItem> orderItems) {

        this.orderItems = orderItems;

    }

}

OrderItemVo

package com.jt.model.vo;

import com.jt.model.Orde;

import com.jt.model.OrdeItem;

/**

 * @author jt

 * @site www.xiaomage.com

 * @company xxx公司

 * @create  2019-10-23 19:01

 */

public class OrderItemVo extends OrdeItem {

    private Orde orde;

    public Orde getOrde() {

        return orde;

    }

    public void setOrde(Orde orde) {

        this.orde = orde;

    }

}

CategoryVo

package com.jt.model.vo;

import com.jt.model.Category;

import com.jt.model.Hbook;

import java.util.ArrayList;

import java.util.List;

/**

 * @author jt

 * @site www.xiaomage.com

 * @company xxx公司

 * @create  2019-10-23 20:08

 */

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;

    }

}

HbookVo

package com.jt.model.vo;

import com.jt.model.Category;

import com.jt.model.Hbook;

import java.util.ArrayList;

import java.util.List;

/**

 * @author jt

 * @site www.xiaomage.com

 * @company xxx公司

 * @create  2019-10-23 20:06

 */

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;

//    }

    public List<Category> getCategories() {

        return categories;

    }

    public void setCategories(List<Category> categories) {

        this.categories = categories;

    }

}

4.做一个测试（根据id来查询）

 @Test

    public void selectByOrderItemId() {

        List<OrderItemVo> orderItemVos = oneToManyService.selectByOrderItemId();

        OrderItemVo orderItemVo=orderItemVos.get();

        System.out.println(orderItemVo);

        System.out.println(orderItemVo.getOrde());

    }

    @Test

    public void selectByOrderId() {

        List<OrderVo> orderVos = oneToManyService.selectByOrderId();

        OrderVo orderVo=orderVos.get();

//        System.out.println(orderVos.size());

        System.out.println(orderVo);

        for (OrdeItem orderItem : orderVo.getOrderItems()) {

            System.out.println(orderItem);

        }

    }

通过一个订单项的id，查询出订单项信息的同时，查询出所属的订单 mybatis之关联关系-LMLPHP

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 mybatis之关联关系-LMLPHP

2、多对多关联关系

首先先用逆向生成工具生成t_hibernate_book、t_hibernate_book_category（可生成可不生成）、t_hibernate_category，这两张表对应的model与mapper
generatorConfig.xml

<?xml version="1.0" encoding="UTF-8" ?>

<!DOCTYPE generatorConfiguration PUBLIC "-//mybatis.org//DTD MyBatis Generator Configuration 1.0//EN"

        "http://mybatis.org/dtd/mybatis-generator-config_1_0.dtd" >

<generatorConfiguration>

    <!-- 引入配置文件 -->

    <properties resource="jdbc.properties"/>

    <!--指定数据库jdbc驱动jar包的位置-->

    <classPathEntry location="D:\\initpath\\mvn_repository\\mysql\\mysql-connector-java\\5.1.44\\mysql-connector-java-5.1.44.jar"/>

    <!-- 一个数据库一个context -->

    <context id="infoGuardian">

        <!-- 注释 -->

        <commentGenerator>

            <property name="suppressAllComments" value="true"/><!-- 是否取消注释 -->

            <property name="suppressDate" value="true"/> <!-- 是否生成注释代时间戳 -->

        </commentGenerator>

        <!-- jdbc连接 -->

        <jdbcConnection driverClass="${jdbc.driver}"

                        connectionURL="${jdbc.url}" userId="${jdbc.username}" password="${jdbc.password}"/>

        <!-- 类型转换 -->

        <javaTypeResolver>

            <!-- 是否使用bigDecimal， false可自动转化以下类型（Long, Integer, Short, etc.） -->

            <property name="forceBigDecimals" value="false"/>

        </javaTypeResolver>

        <!--  指定javaBean生成的位置 -->

        <!-- targetPackage：指定生成的model生成所在的包名 -->

        <!-- targetProject：指定在该项目下所在的路径  -->

        <javaModelGenerator targetPackage="com.jt.model"

                            targetProject="src/main/java">

            <!-- 是否允许子包，即targetPackage.schemaName.tableName -->

            <property name="enableSubPackages" value="false"/>

            <!-- 是否对model添加构造函数 -->

            <property name="constructorBased" value="true"/>

            <!-- 是否针对string类型的字段在set的时候进行trim调用 -->

            <property name="trimStrings" value="false"/>

            <!-- 建立的Model对象是否 不可改变  即生成的Model对象不会有 setter方法，只有构造方法 -->

            <property name="immutable" value="false"/>

        </javaModelGenerator>

        <!--  指定sql映射文件生成的位置 -->

        <sqlMapGenerator targetPackage="com.jt.mapper"

                         targetProject="src/main/java">

            <!-- 是否允许子包，即targetPackage.schemaName.tableName -->

            <property name="enableSubPackages" value="false"/>

        </sqlMapGenerator>

        <!--  生成XxxMapper接口 -->

        <!-- type="ANNOTATEDMAPPER",生成Java Model 和基于注解的Mapper对象 -->

        <!-- type="MIXEDMAPPER",生成基于注解的Java Model 和相应的Mapper对象 -->

        <!-- type="XMLMAPPER",生成SQLMap XML文件和独立的Mapper接口 -->

        <javaClientGenerator targetPackage="com.jt.mapper"

                             targetProject="src/main/java" type="XMLMAPPER">

            <!-- 是否在当前路径下新加一层schema,false路径com.oop.eksp.user.model， true:com.oop.eksp.user.model.[schemaName] -->

            <property name="enableSubPackages" value="false"/>

        </javaClientGenerator>

        <!-- 配置表信息 -->

        <!-- schema即为数据库名 -->

        <!-- tableName为对应的数据库表 -->

        <!-- domainObjectName是要生成的实体类 -->

        <!-- enable*ByExample是否生成 example类 -->

        <!--<table schema="" tableName="t_book" domainObjectName="Book"-->

        <!--enableCountByExample="false" enableDeleteByExample="false"-->

        <!--enableSelectByExample="false" enableUpdateByExample="false">-->

        <!--&lt;!&ndash; 忽略列，不生成bean 字段 &ndash;&gt;-->

        <!--&lt;!&ndash; <ignoreColumn column="FRED" /> &ndash;&gt;-->

        <!--&lt;!&ndash; 指定列的java数据类型 &ndash;&gt;-->

        <!--&lt;!&ndash; <columnOverride column="LONG_VARCHAR_FIELD" jdbcType="VARCHAR" /> &ndash;&gt;-->

        <!--</table>-->

       <!-- <table schema="" tableName="t_hibernate_order" domainObjectName="Orde"

               enableCountByExample="false" enableDeleteByExample="false"

               enableSelectByExample="false" enableUpdateByExample="false">

            &lt;!&ndash; 忽略列，不生成bean 字段 &ndash;&gt;

            &lt;!&ndash; <ignoreColumn column="FRED" /> &ndash;&gt;

            &lt;!&ndash; 指定列的java数据类型 &ndash;&gt;

            &lt;!&ndash; <columnOverride column="LONG_VARCHAR_FIELD" jdbcType="VARCHAR" /> &ndash;&gt;

        </table>-->

        <!--<table schema="" tableName="t_hibernate_order_item" domainObjectName="OrdeItem"

               enableCountByExample="false" enableDeleteByExample="false"

               enableSelectByExample="false" enableUpdateByExample="false">

            &lt;!&ndash; 忽略列，不生成bean 字段 &ndash;&gt;

            &lt;!&ndash; <ignoreColumn column="FRED" /> &ndash;&gt;

            &lt;!&ndash; 指定列的java数据类型 &ndash;&gt;

            &lt;!&ndash; <  columnOverride column="LONG_VARCHAR_FIELD" jdbcType="VARCHAR" /> &ndash;&gt;

        </table>-->

        <table schema="" tableName="t_hibernate_book`" domainObjectName="Hbook"

               enableCountByExample="false" enableDeleteByExample="false"

               enableSelectByExample="false" enableUpdateByExample="false">

            <!-- 忽略列，不生成bean 字段 -->

            <!-- <ignoreColumn column="FRED" /> -->

            <!-- 指定列的java数据类型 -->

            <!-- <columnOverride column="LONG_VARCHAR_FIELD" jdbcType="VARCHAR" /> -->

        </table>

        <!--<table schema="" tableName="t_hibernate_category" domainObjectName="Category"

               enableCountByExample="false" enableDeleteByExample="false"

               enableSelectByExample="false" enableUpdateByExample="false">

            &lt;!&ndash; 忽略列，不生成bean 字段 &ndash;&gt;

            &lt;!&ndash; <ignoreColumn column="FRED" /> &ndash;&gt;

            &lt;!&ndash; 指定列的java数据类型 &ndash;&gt;

            &lt;!&ndash; <columnOverride column="LONG_VARCHAR_FIELD" jdbcType="VARCHAR" /> &ndash;&gt;

        </table>-->

       <!-- <table schema="" tableName="t_hibernate_book_category" domainObjectName="HbookCategory"

               enableCountByExample="false" enableDeleteByExample="false"

               enableSelectByExample="false" enableUpdateByExample="false">

            &lt;!&ndash; 忽略列，不生成bean 字段 &ndash;&gt;

            &lt;!&ndash; <ignoreColumn column="FRED" /> &ndash;&gt;

            &lt;!&ndash; 指定列的java数据类型 &ndash;&gt;

            &lt;!&ndash; <columnOverride column="LONG_VARCHAR_FIELD" jdbcType="VARCHAR" /> &ndash;&gt;

        </table>-->

    </context>

</generatorConfiguration>

HBookMapper

package com.jt.mapper;

import com.jt.model.Hbook;

import com.jt.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);

}

HBookMapper.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.jt.mapper.HbookMapper" >

  <resultMap id="BaseResultMap" type="com.jt.model.Hbook" >

    <constructor >

      <idArg column="book_id" jdbcType="INTEGER" javaType="java.lang.Integer" />

      <arg column="book_name" jdbcType="VARCHAR" javaType="java.lang.String" />

      <arg column="price" jdbcType="REAL" javaType="java.lang.Float" />

    </constructor>

  </resultMap>

  <resultMap id="HbookVoMap" type="com.jt.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.jt.model.Category">

      <result property="categoryId" column="category_id"></result>

      <result property="categoryName" column="category_name"></result>

    </collection>

  </resultMap>

  <sql id="Base_Column_List" >

    book_id, book_name, price

  </sql>

  <select id="selectByPrimaryKey" resultMap="BaseResultMap" parameterType="java.lang.Integer" >

    select

    <include refid="Base_Column_List" />

    from t_hibernate_book

    where book_id = #{bookId,jdbcType=INTEGER}

  </select>

  <delete id="deleteByPrimaryKey" parameterType="java.lang.Integer" >

    delete from t_hibernate_book

    where book_id = #{bookId,jdbcType=INTEGER}

  </delete>

  <insert id="insert" parameterType="com.jt.model.Hbook" >

    insert into t_hibernate_book (book_id, book_name, price

      )

    values (#{bookId,jdbcType=INTEGER}, #{bookName,jdbcType=VARCHAR}, #{price,jdbcType=REAL}

      )

  </insert>

  <insert id="insertSelective" parameterType="com.jt.model.Hbook" >

    insert into t_hibernate_book

    <trim prefix="(" suffix=")" suffixOverrides="," >

      <if test="bookId != null" >

        book_id,

      </if>

      <if test="bookName != null" >

        book_name,

      </if>

      <if test="price != null" >

        price,

      </if>

    </trim>

    <trim prefix="values (" suffix=")" suffixOverrides="," >

      <if test="bookId != null" >

        #{bookId,jdbcType=INTEGER},

      </if>

      <if test="bookName != null" >

        #{bookName,jdbcType=VARCHAR},

      </if>

      <if test="price != null" >

        #{price,jdbcType=REAL},

      </if>

    </trim>

  </insert>

  <update id="updateByPrimaryKeySelective" parameterType="com.jt.model.Hbook" >

    update t_hibernate_book

    <set >

      <if test="bookName != null" >

        book_name = #{bookName,jdbcType=VARCHAR},

      </if>

      <if test="price != null" >

        price = #{price,jdbcType=REAL},

      </if>

    </set>

    where book_id = #{bookId,jdbcType=INTEGER}

  </update>

  <update id="updateByPrimaryKey" parameterType="com.jt.model.Hbook" >

    update t_hibernate_book

    set book_name = #{bookName,jdbcType=VARCHAR},

      price = #{price,jdbcType=REAL}

    where book_id = #{bookId,jdbcType=INTEGER}

  </update>

  <select id="selectByBid" resultMap="HbookVoMap" >

    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>

</mapper>

HBookCategoryMapper

package com.jt.mapper;

import com.jt.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);

}

HBookCategoryMapper.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.jt.mapper.HbookCategoryMapper" >

  <resultMap id="BaseResultMap" type="com.jt.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_category

    where bcid = #{bcid,jdbcType=INTEGER}

  </select>

  <delete id="deleteByPrimaryKey" parameterType="java.lang.Integer" >

    delete from t_hibernate_book_category

    where bcid = #{bcid,jdbcType=INTEGER}

  </delete>

  <insert id="insert" parameterType="com.jt.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.jt.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.jt.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.jt.model.HbookCategory" >

    update t_hibernate_book_category

    set bid = #{bid,jdbcType=INTEGER},

      cid = #{cid,jdbcType=INTEGER}

    where bcid = #{bcid,jdbcType=INTEGER}

  </update>

</mapper>

测试方法

   @Autowired

    private ManyToManyService manyToManyService;

    @Test

    public void selectByBid() {

        HbookVo hbookVo = manyToManyService.selectByBid();

        System.out.println(hbookVo);

        for (Category category : hbookVo.getCategories()) {

            System.out.println(category);

        }

    }

    @Test

    public void selectByCid() {

        CategoryVo categoryVo=this.manyToManyService.selectByCid();

        System.out.println(categoryVo);

        for (Hbook hbook : categoryVo.getHbooks()) {

            System.out.println(hbook);

        }

    }

mybatis之关联关系-LMLPHP