MyBatis框架中嵌套结果（一对一查询）

IdCard类

package com.hkd.pojo;

public class IdCard {
    int id;
    String code;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getCode() {
        return code;
    }

    public void setCode(String code) {
        this.code = code;
    }

    @Override
    public String toString() {
        return "IdCard{" +
                "id=" + id +
                ", code='" + code + '\'' +
                '}';
    }
}

Person类

package com.hkd.pojo;

public class Person {
    int id;
    String name;
    int age;
    String sex;
    IdCard card;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    public IdCard getCard() {
        return card;
    }

    public void setCard(IdCard card) {
        this.card = card;
    }
    @Override
    public String toString() {
        return "Person{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", age=" + age +
                ", sex='" + sex + '\'' +
                ", card=" + card +
                '}';
    }
}

IdCardMapper.xml文件

<?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.hkd.pojo.IdCard">
<select id="findCodeById" resultType="IdCard" parameterType="int">
    select * from tb_idcard where id=#{id}
</select>
</mapper>

PersonMapper.xml文件

<?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.hkd.pojo.Person">
<select id="findPersonById" parameterType="int" resultMap="IdCardWithPersonResult">
    select * from tb_person where id=#{id}
</select>
    <resultMap id="IdCardWithPersonResult" type="Person">
        <id property="id" column="id"></id>
        <result property="name" column="name"/>
        <result property="age" column="age"/>
        <result property="sex" column="sex"/>
       <association property="card" column="card_id" javaType="IdCard">
           <id property="id" column="card_id"/>
           <result property="code" column="code"/>
       </association>
    </resultMap>

</mapper>

db.properties文件

jdbc.driver=com.mysql.cj.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/mybatis
jdbc.username=root
jdbc.password=root

mybatis-config.xml核心配置文件

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
    <properties resource="db.properties"></properties>
    <typeAliases>
        <package name="com.hkd.pojo"/>
    </typeAliases>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"></transactionManager>
            <dataSource type="POOLED">
                <property name="driver" value="${jdbc.driver}"/>
                <property name="url" value="${jdbc.url}"/>
                <property name="username" value="${jdbc.username}"/>
                <property name="password" value="${jdbc.password}"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="mapper/IdCardMapper.xml"/>
        <mapper resource="mapper/PersonMapper.xml"/>
    </mappers>
</configuration>

测试类

import com.hkd.pojo.Person;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import java.io.IOException;
import java.io.Reader;

public class Test {
    @org.junit.Test
    public void findById() throws IOException {
        String resource="mybatis-config.xml";
        Reader reader= Resources.getResourceAsReader(resource);
        SqlSessionFactory sqlSessionFactory=new SqlSessionFactoryBuilder().build(reader);
        SqlSession sqlSession=sqlSessionFactory.openSession();
        Person person=sqlSession.selectOne("findPersonById",1);
        System.out.println(person);
        sqlSession.commit();
        sqlSession.close();
    }
}
pom.xml依赖

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>org.example</groupId>
    <artifactId>homework10</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <maven.compiler.source>17</maven.compiler.source>
        <maven.compiler.target>17</maven.compiler.target>
    </properties>
    <dependencies>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.28</version>
        </dependency>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.11</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.1.20</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>
    </dependencies>
</project>

目录