mybatis源碼深度解析，mybatis resultType解析

resultType是sql映射文件中定義返回值類型，返回值有基本類型，對象類型，List類型，Map類型等。現總結一下再解釋

總結：

resultType:

1、基本類型 ?：resultType=基本類型

2、List類型： ? resultType=List中元素的類型

mybatis源碼深度解析，3、Map類型 ? ?單條記錄：resultType =map

? ? ? ? ? ? ? ? ? ? ? ? ? 多條記錄：resultType =Map中value的類型

1、對象類型

對于對象類型resultType直接寫對象的全類名就可以了

實例：

hotelMapper接口

MyBatis、

package com.pjf.mybatis.dao;import com.pjf.mybatis.po.Hotel;public interface HotelMapper {//返回值類型為Hotelpublic Hotel getHotel(Integer i);}

HotelMapper.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.pjf.mybatis.dao.HotelMapper"><!--resultType直接寫對象的全類名 --><select id="getHotel" resultType="com.pjf.mybatis.po.Hotel">select * from hotelwhereid=#{id}</select>
</mapper>

result？測試類：

package com.pjf.mybatis;import java.io.IOException;
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 org.junit.Test;import com.pjf.mybatis.dao.HotelMapper;
import com.pjf.mybatis.po.Hotel;public class TestHotel {public SqlSessionFactory sqlSessionFactory() throws IOException {// mybatis的配置文件String resource = "mybatis_config.xml";// 使用類加載器加載mybatis的配置文件（它也加載關聯的映射文件）TestHotel.class.getClassLoader()InputStream is = Resources.getResourceAsStream(resource);// 構建sqlSession的工廠SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(is);return sessionFactory;}// 查@Testpublic void getHotel() throws IOException {SqlSessionFactory sessionFactory = sqlSessionFactory();SqlSession session = sessionFactory.openSession();HotelMapper hotelMapper = session.getMapper(HotelMapper.class);System.out.println(hotelMapper.getClass());//直接返回Hotel對象，打印出來        Hotel hotel = hotelMapper.getHotel(1001);System.out.println(hotel);session.close();}}

2、List類型

返回值為List類型，resultType為List中對象的類型，如List<Hotel>，resultType為Hotel

實例：

resultType？hotelMapper接口

package com.pjf.mybatis.dao;import java.util.List;import com.pjf.mybatis.po.Hotel;public interface HotelMapper {// 返回值為Listpublic List<Hotel> getHotel(Integer i);
}

hotelMapper.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.pjf.mybatis.dao.HotelMapper"><!-- 返回值為List，resultType為List中元素的全類名 --><select id="getHotel" resultType="com.pjf.mybatis.po.Hotel">select * from hotelwhereprice>#{price}</select>
</mapper>

parameterType、

測試類

package com.pjf.mybatis;import java.io.IOException;
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 org.junit.Test;import com.pjf.mybatis.dao.HotelMapper;
import com.pjf.mybatis.po.Hotel;public class TestHotel {public SqlSessionFactory sqlSessionFactory() throws IOException {// mybatis的配置文件String resource = "mybatis_config.xml";// 使用類加載器加載mybatis的配置文件（它也加載關聯的映射文件）TestHotel.class.getClassLoader()InputStream is = Resources.getResourceAsStream(resource);// 構建sqlSession的工廠SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(is);return sessionFactory;}// 查@Testpublic void getHotel() throws IOException {SqlSessionFactory sessionFactory = sqlSessionFactory();SqlSession session = sessionFactory.openSession();HotelMapper hotelMapper = session.getMapper(HotelMapper.class);System.out.println(hotelMapper.getClass());// 返回值為ListList<Hotel> list = hotelMapper.getHotel(1000);for (Hotel hotel : list) {System.out.println(hotel);}session.close();}
}

3、Map類型

a、返回單條記錄的map，key為屬性，值為屬性值。resultType為map

the type list is not generic？hotelMapper接口

package com.pjf.mybatis.dao;import java.util.Map;
import com.pjf.mybatis.po.Hotel;public interface HotelMapper {// 返回值為Map，key為屬性名，value為屬性值public Map<String, Object> getHotel(Integer i);
}

hotelMapper.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.pjf.mybatis.dao.HotelMapper"><!-- 返回值為map，resultType為map --><select id="getHotel" resultType="map">select * from hotelwhereid=#{id}</select>
</mapper>

resulttype爆紅，

測試類，返回id=1001的酒店

package com.pjf.mybatis;import java.io.IOException;
import java.io.InputStream;
import java.util.Map;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 org.junit.Test;import com.pjf.mybatis.dao.HotelMapper;
import com.pjf.mybatis.po.Hotel;public class TestHotel {public SqlSessionFactory sqlSessionFactory() throws IOException {// mybatis的配置文件String resource = "mybatis_config.xml";// 使用類加載器加載mybatis的配置文件（它也加載關聯的映射文件）TestHotel.class.getClassLoader()InputStream is = Resources.getResourceAsStream(resource);// 構建sqlSession的工廠SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(is);return sessionFactory;}// 查@Testpublic void getHotel() throws IOException {SqlSessionFactory sessionFactory = sqlSessionFactory();SqlSession session = sessionFactory.openSession();HotelMapper hotelMapper = session.getMapper(HotelMapper.class);System.out.println(hotelMapper.getClass());// 返回值為mapMap<String, Object> map = hotelMapper.getHotel(1001);System.out.println(map);session.close();}
}

b、返回多條記錄的map，key為任意一屬性，值為對象類型。如Map<String,Hotel>,resultType為Hotel

resulttype為list、返回多條記錄的map時，key為任意一屬性，值為對象類型，不過key需要通過@MapKey("hotelName")指定對象中一個屬性名為key

實例：

hotelMapper接口

package com.pjf.mybatis.dao;import java.util.Map;
import org.apache.ibatis.annotations.MapKey;import com.pjf.mybatis.po.Hotel;public interface HotelMapper {// 返回值為Map，key需要通過@MapKey("屬性名")來指定javaBean中的一個屬性名為key，value為對象@MapKey("hotelName")public Map<String, Hotel> getHotel(Integer i);
}

resulttype int。hotelMapper.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.pjf.mybatis.dao.HotelMapper"><!-- 返回值為map，resultType為對象的全類名 --><select id="getHotel" resultType="com.pjf.mybatis.po.Hotel">select * from hotelwhereprice>#{price}</select>
</mapper>

測試類：返回價格>1000以上的酒店

package com.pjf.mybatis;import java.io.IOException;
import java.io.InputStream;
import java.util.Map;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 org.junit.Test;import com.pjf.mybatis.dao.HotelMapper;
import com.pjf.mybatis.po.Hotel;public class TestHotel {public SqlSessionFactory sqlSessionFactory() throws IOException {// mybatis的配置文件String resource = "mybatis_config.xml";// 使用類加載器加載mybatis的配置文件（它也加載關聯的映射文件）TestHotel.class.getClassLoader()InputStream is = Resources.getResourceAsStream(resource);// 構建sqlSession的工廠SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(is);return sessionFactory;}// 查@Testpublic void getHotel() throws IOException {SqlSessionFactory sessionFactory = sqlSessionFactory();SqlSession session = sessionFactory.openSession();HotelMapper hotelMapper = session.getMapper(HotelMapper.class);System.out.println(hotelMapper.getClass());// 返回值為mapMap<String, Hotel> map = hotelMapper.getHotel(1000);System.out.println(map);session.close();}
}

resulttype返回list、?

本文轉載于博客園?https://www.cnblogs.com/pjfmeng/p/7688172.html

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