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
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(36);
OrderItemVo orderItemVo=orderItemVos.get(0);
System.out.println(orderItemVo);
System.out.println(orderItemVo.getOrde());
}
@Test
public void selectByOrderId() {
List<OrderVo> orderVos = oneToManyService.selectByOrderId(8);
OrderVo orderVo=orderVos.get(0);
// 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
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
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>
<!-- 01 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>
<!-- 02 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>
<!-- 03 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">-->
<!--<!– 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_order" domainObjectName="Orde"
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_order_item" domainObjectName="OrdeItem"
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_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">
<!– 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_book_category" domainObjectName="HbookCategory"
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>-->
</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(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);
}
}