MyBatis框架基于Annotation注解的一对一关联映射

忘是亡心i 2022-06-18 08:27 241阅读 0赞

代码：

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">
      
    <configuration>
    	<properties resource="db.properties"/>
    	
    	<settings>
    		<setting name="logImpl" value="LOG4J"/>
    	</settings>
    	
    	<environments default="mysql">
    	
        <environment id="mysql">
        
          <transactionManager type="JDBC"/>
          
          <dataSource type="POOLED">
            <property name="driver" value="${driver}"/>
            <property name="url" value="${url}"/>
            <property name="username" value="${username}"/>
            <property name="password" value="${password}"/>
          </dataSource>
        </environment>
      </environments> 
      
      
      <mappers>
      	<mapper class="com.mapper.PersonMapper"/> 
      	<mapper class="com.mapper.CardMapper"/> 
      </mappers>
    </configuration>

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;  // 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;
    
    	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 + "]";
    	} 
    	
    }

FKSqlSessionFactory.java

package com.factory;
    
    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;
    
    public class FKSqlSessionFactory {
    	
    	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;
    	}
    
    }

CardMapper.xml

package com.mapper;
    
    import org.apache.ibatis.annotations.Select;
    
    import com.bean.Card;
    
    public interface CardMapper {
    	@Select("select * from tb_card where id = #{id} ")
    	Card selectCardById(Integer id);
    }

PersonMapper.xml

package com.mapper;
    
    import org.apache.ibatis.annotations.One;
    import org.apache.ibatis.annotations.Result;
    import org.apache.ibatis.annotations.Results;
    import org.apache.ibatis.annotations.Select;
    import org.apache.ibatis.mapping.FetchType;
    
    import com.bean.Person;
    
    public interface PersonMapper {
    	@Select("select * from tb_person where id = #{id}")
    	@Results({
    		@Result(id=true,column="id",property="id"),
    		@Result(column="name",property="name"),
    		@Result(column="sex",property="sex"),
    		@Result(column="age",property="age"),
    		@Result(column="card_id",property="card",one=@One(
    				select="com.mapper.CardMapper.selectCardById",fetchType=FetchType.EAGER))
    	})
    	Person selectPersonById(Integer id);
    }

OneToOneTest.java

package com.test;
    
    import org.apache.ibatis.session.SqlSession;
    
    import com.bean.Person;
    import com.factory.FKSqlSessionFactory;
    import com.mapper.PersonMapper;
    
    public class OneToOneTest {
    
    	public static void main(String[] args) {
    		// TODO Auto-generated method stub
           SqlSession session=FKSqlSessionFactory.getSqlSession();
           // 获取PersonMapper实例
           PersonMapper pm = session.getMapper(PersonMapper.class);
           // 根据id查询Person对象，同时需要获得关联的Card对象
           Person p = pm.selectPersonById(1);
           System.out.println(p);
    	   // 查看查询到的关联的Card对象
    	   System.out.println(p.getCard());
    	   session.commit();
    	   session.close();
    	}
    
    }

截图：

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[Center]: /images/20220618/92dff6c99d9d40e9a58ceeb70be326fb.png