MyBatis @Result注解基于一对一关联

我就是我 2022-05-14 05:29 200阅读 0赞

### 示例：测试一对一关联 ###

**程序清单：com.mapper.PersonMapper.java**

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.po.Person;
    public interface PersonMapper {
    	@Select("select * from t_person where id=#{id}")
    	@Results({
    		@Result(id=true,column="id",property="id"),
    		@Result(column="name",property="name"),
    		@Result(column="cid",property="card",
    		one=@One(select="com.mapper.CardMapper.getCardById",
    		fetchType=FetchType.EAGER))
    	})
    	Person getPersonById(Integer id);
    }

**程序清单：com.mapper.CardMapper.java**

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

**程序清单：com.po.Person.java**

package com.po;
    public class Person {
    	private Integer id;
    	private String name;
    	private Card card;
    	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 Card getCard() {
    		return card;
    	}
    	public void setCard(Card card) {
    		this.card = card;
    	}
    	@Override
    	public String toString() {
    		return "Person [id=" + id + ", name=" + name + ", card=" + card + "]";
    	}
    }

**程序清单：com.po.Card.java**

package com.po;
    public class Card {
    	private Integer id;
    	private String code;
    	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() {
    		return "Card [id=" + id + ", code=" + code + "]";
    	}
    }

**程序清单：/mybatis/src/mybatis-config.xml**

<mappers>
    		<mapper class="com.mapper.PersonMapper"/>	
    		<mapper class="com.mapper.CardMapper"/>			
    	</mappers>

**程序清单：com.dao.PersonDao.java**

@Test
    	public void getPersonById() throws IOException {
    		session=getSqlSession();
    		PersonMapper pm=session.getMapper(PersonMapper.class);
    		Person person=pm.getPersonById(1);
    		System.out.println(person);
    	}

**运行PersonDao的getPersonById()方法，控制台显示如下：**

![70][]

[70]: /images/20220514/ecb2d04e9ea549cf8ab2358ae4de9d20.png