mybatis关联映射一对一

在项目开发中，会存在一对一的关系，比如一个人只有一个身份证，一个身份证只能给一个人使用，这就是一对一关系。一对一关系使用主外键关联。

table.sql,在数据库中创建如下两个表并插入数据

CREATE TABLE T_CARD(
	ID INT PRIMARY KEY AUTO_INCREMENT,
	CODE VARCHAR(20)
);
INSERT INTO T_CARD(CODE)VALUES('130113198701274657');

CREATE TABLE T_PERSON(
	ID INT PRIMARY KEY AUTO_INCREMENT,
	NAME VARCHAR(20) DEFAULT NULL,
	SEX CHAR(20) DEFAULT NULL,
	AGE INT(11) DEFAULT NULL,
	CARD_ID INT UNIQUE,
 FOREIGN KEY(CARD_ID) REFERENCES T_CARD(ID)
);
INSERT INTO T_PERSON(NAME,SEX,AGE,CARD_ID) VALUES('张三','男','23',1);

mybatis-config.xml

<?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">
  <!--  XML 配置文件包含对 MyBatis 系统的核心设置 -->
<configuration>
	<!-- 指定 MyBatis 所用日志的具体实现 -->
	<settings>
		<setting name="logImpl" value="LOG4J"/>
	</settings>
	<environments default="mysql">
	<!-- 环境配置，即连接的数据库。 -->
    <environment id="mysql">
    <!--  指定事务管理类型，type="JDBC"指直接简单使用了JDBC的提交和回滚设置 -->
      <transactionManager type="JDBC"/>
      <!--  dataSource指数据源配置，POOLED是JDBC连接对象的数据源连接池的实现。 -->
      <dataSource type="POOLED">
        <property name="driver" value="com.mysql.jdbc.Driver"/>
        <property name="url" value="jdbc:mysql://192.168.47.151:3306/mybatis"/>
        <property name="username" value="root"/>
        <property name="password" value="root"/>
      </dataSource>
    </environment>
  </environments>
  <!-- mappers告诉了MyBatis去哪里找持久化类的映射文件 -->
  <mappers>
  	<mapper resource="mapper/CardMapper.xml"/>
  	<mapper resource="mapper/PersonMapper.xml"/>
  </mappers>
</configuration>

PersonMapper.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">
<!-- namespace指用户自定义的命名空间。 -->
<mapper namespace="com.rookie.bigdata.mapper.PersonMapper">


    <parameterMap type="com.rookie.bigdata.domain.Person" id="parameterPersonMap">
        <parameter property="id"/>
        <parameter property="name"/>
        <parameter property="sex"/>
        <parameter property="age"/>
    </parameterMap>

    <insert id="insertPerson" parameterMap="parameterPersonMap">
        <selectKey keyProperty="id" resultType="int" order="AFTER">
            SELECT LAST_INSERT_ID() AS ID
        </selectKey>
        INSERT INTO t_person(name,sex,age,card_id)
        VALUES(#{name},#{sex},#{age},#{card.id})    <!--记得不要有逗号-->
    </insert>

    <!-- 根据id查询Person，返回resultMap -->
    <select id="selectPersonById" parameterType="int"
            resultMap="personMapper">
  	SELECT * from t_person where id = #{id}
  </select>

    <!-- 映射Peson对象的resultMap -->
    <resultMap type="com.rookie.bigdata.domain.Person" id="personMapper">
        <id property="id" column="id"/>
        <result property="name" column="name"/>
        <result property="sex" column="sex"/>
        <result property="age" column="age"/>
        <!-- 一对一关联映射:association   -->
        <association property="card" column="card_id"
                     select="com.rookie.bigdata.mapper.CardMapper.selectCardById"
                     javaType="com.rookie.bigdata.domain.Card"/>
    </resultMap>

</mapper>

CardMapper.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">
<!-- namespace指用户自定义的命名空间。 -->
<mapper namespace="com.rookie.bigdata.mapper.CardMapper">

    <!-- 根据id查询Card，返回Card对象 -->
    <select id="selectCardById" parameterType="int" resultType="com.rookie.bigdata.domain.Card">
  	SELECT * from t_card where id = #{id}
  </select>

    <parameterMap type="com.rookie.bigdata.domain.Card" id="cardMap">
        <parameter property="id"/>
        <parameter property="code"/>
    </parameterMap>

    <insert id="insertCard" parameterMap="cardMap">
        <selectKey keyProperty="id" resultType="int" order="AFTER">
            SELECT LAST_INSERT_ID() AS ID
        </selectKey>
        INSERT INTO T_CARD(id,code)
        VALUES(?,?)
    </insert>


</mapper>

Card.java

public class Card implements Serializable {
	
	private Integer id;  // 主键id
	private String code; // 身份证编号
}

Person.java

public class Person implements Serializable {

	private Integer id;  // 主键id
	private String name; // 姓名
	private String sex;  // 性别
	private Integer age; // 年龄
	
	// 人和身份证是一对一的关系，即一个人只有一个身份证
	private Card card; 

CardMapper.java

public interface CardMapper {

    void insertCard(Card card);

}

PersonMapper.java

public interface PersonMapper {

    /**
     * 根据id查询Person
     */
    Person selectPersonById(Integer id);


    /**
     * 插入数据
     * @param person
     */
    void insertPerson(Person person);

}

SqlSessionFactoryUtil.java

package com.rookie.bigdata.utils;

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.InputStream;

public class SqlSessionFactoryUtil {
	
	private static SqlSessionFactory sqlSessionFactory = null;
	
	// 初始化创建SqlSessionFactory对象
	static{
		try {
			// 读取mybatis-config.xml文件
			InputStream inputStream = Resources.getResourceAsStream("mybatis-config.xml");
			sqlSessionFactory = new SqlSessionFactoryBuilder()
					.build(inputStream);
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
	
	// 获取SqlSession对象的静态方法
	public static SqlSession getSqlSession(){
		return sqlSessionFactory.openSession();
	}

	// 获取SqlSessionFactory的静态方法
	public static SqlSessionFactory getSqlSessionFactory() {
		return sqlSessionFactory;
	}

}

测试代码进行增查操作

package com.rookie.bigdata.test;


import com.rookie.bigdata.domain.Card;
import com.rookie.bigdata.domain.Person;
import com.rookie.bigdata.mapper.CardMapper;
import com.rookie.bigdata.mapper.PersonMapper;
import com.rookie.bigdata.utils.SqlSessionFactoryUtil;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.transaction.Transaction;
import org.apache.ibatis.transaction.TransactionFactory;
import org.apache.ibatis.transaction.jdbc.JdbcTransactionFactory;
import org.junit.Test;


public class OneToOneTest {

    @Test
    public  void test() throws Exception {
        // 创建Session实例
        SqlSession session = SqlSessionFactoryUtil.getSqlSession();

        // 获得mapper接口的代理对象
        PersonMapper pm = session.getMapper(PersonMapper.class);
        // 直接调用接口的方法，查询id为1的Peson数据
        Person p = pm.selectPersonById(1);
        // 打印Peson对象
        System.out.println(p);
        // 打印Person对象关联的Card对象
        System.out.println(p.getCard());

        // 提交事务
        session.commit();
        // 关闭Session
        session.close();
    }

    @Test
    public void test1() throws Exception {
        SqlSession sqlSession = SqlSessionFactoryUtil.getSqlSession();
        TransactionFactory transactionFactory = new JdbcTransactionFactory();
        Transaction tx = transactionFactory.newTransaction(sqlSession
                .getConnection());

        Card card = new Card();
        card.setCode("130442154542048521");

        Person person = new Person();
        person.setName("lisi");
        person.setSex("男");
        person.setAge(30);
        person.setCard(card);


        PersonMapper personMapper = sqlSession.getMapper(PersonMapper.class);
        CardMapper cardMapper = sqlSession.getMapper(CardMapper.class);

        cardMapper.insertCard(card);
        personMapper.insertPerson(person);

        System.out.println(card.getId());

       tx.commit();


    }


}

进行测试完美解决