MyBatis框架的一对一关联映射

逃离我推掉我的手 2022-06-18 00:58 164阅读 0赞

代码：

Card.java

package com.bean;
    
    import java.io.Serializable;
    
    public class Card implements Serializable {
    	private Integer id;  // 主键id
    	private String code; // 身份证编号
    	public Card() {
    		super();
    		// TODO Auto-generated constructor stub
    	}
    	public Integer getId() {
    		return id;
    	}
    	public void setId(Integer id) {
    		this.id = id;
    	}
    	public String getCode() {
    		return code;
    	}
    	public void setCode(String code) {
    		this.code = code;
    	}
    	@Override
    	public String toString() {
    		// TODO Auto-generated method stub
    		return "Card [id=" + id + ", code=" + code + "]";
    	}
    	
    }

Person.java

package com.bean;
    
    import java.io.Serializable;
    
    public class Person implements Serializable {
    	private Integer id;  
    	private String name; 
    	private String sex;  
    	private Integer age; 
    	
    	// 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;
    
    	public Person() {
    		super();
    		// TODO Auto-generated constructor stub
    	}
    
    	public Integer getId() {
    		return id;
    	}
    
    	public void setId(Integer id) {
    		this.id = id;
    	}
    
    	public String getName() {
    		return name;
    	}
    
    	public void setName(String name) {
    		this.name = name;
    	}
    
    	public String getSex() {
    		return sex;
    	}
    
    	public void setSex(String sex) {
    		this.sex = sex;
    	}
    
    	public Integer getAge() {
    		return age;
    	}
    
    	public void setAge(Integer age) {
    		this.age = age;
    	}
    
    	public Card getCard() {
    		return card;
    	}
    
    	public void setCard(Card card) {
    		this.card = card;
    	}
    
    	@Override
    	public String toString() {
    		// TODO Auto-generated method stub
    		return "Person [id=" + id + ", name=" + name + ", sex=" + sex + ", age=" + age + "]";
    	}
    	
    }

PersonMapper.java

package com.mapper;
    
    import com.bean.Person;
    
    public interface PersonMapper {
       Person selectPersonById(Integer id);
    }

CardMapper.xml

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">
    
    <mapper namespace="com.mapper.PersonMapper">
    	
        <select id="selectPersonById" parameterType="int" resultMap="personMapper">
      	      SELECT * from tb_person where id = #{id} 
        </select>
    
        
    	<resultMap type="com.bean.Person" id="personMapper">
    		<id property="id" column="id"/>
    		<result property="name" column="name"/>
    		<result property="sex" column="sex"/>
    		<result property="age" column="age"/>
    		
    		<association property="card" column="card_id" select="com.mapper.CardMapper.selectCardById" 
    		javaType="com.bean.Card"/>
    	</resultMap>
    
    </mapper>

OneToOneTest.java

package com.test;
    
    import java.io.InputStream;
    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 com.bean.*;
    import com.mapper.PersonMapper;
    
    public class OneToOneTest {
    	public static void main(String[] args) throws Exception {
    		// 读取mybatis-config.xml文件
    		InputStream inputStream = Resources.getResourceAsStream("mybatis-config.xml");
    		// 初始化mybatis，创建SqlSessionFactory类的实例
    		SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
    		// 创建Session实例
    		SqlSession session = sqlSessionFactory.openSession();
    		// 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);
    		System.out.println(p);
    		// 打印Person对象关联的Card对象
    		System.out.println(p.getCard());
    		session.commit();
    		session.close();
    	}
    
    }

截图：

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[Center]: /images/20220618/c7a2ee4bab794b45830834bbc3bbfabf.png