Detailed explanation of resultType and resultMap query operation examples in Mybatis

Only one of the resultType and resultMap can be true. resultType directly represents the return type, while resultMap is a reference to the external ResultMap. resultMap solves the mapping problem of complex queries. For example: if the column name and object attribute name are inconsistent, you can use resultMap to configure it; and the query object contains other objects, etc.

MyBatisConfig.xml

 <?xml version="1.0" encoding="UTF-8" ?><!DOCTYPE configurationPUBLIC "-//mybatis.org//DTD Config 3.0//EN""http://mybatis.org/dtd/mybatis-3-config.dtd"><configuration><!--Defining alias note that typeAlias ​​must be before environments--><typeAliases><typeAlias ​​type="jike.book.pojo.JiKeUser" alias="JiKeUser"/></typeAliases><environments default="development"><environment id="development"><transactionManager type="JDBC"></transactionManager><dataSource type="POOLED"><property name="driver" value="com.mysql.jdbc.Driver"/><property name="url" value="jdbc:mysql://localhost:3306/jikebook"/><property name="username" value="root"/><property name="password" value="****"/></dataSource></environment></environments><mappers><mapper resource="jike/book/map/jikeUser.xml"/><mapper/></mappers></configuration>

jikeUser.xml

 <?xml version="1.0" encoding="UTF-8" ?><!DOCTYPE mapperPUBLIC "-//mybatis.org//DTD Mapper 3.0//EN""http://mybatis.org/dtd/mybatis-3-mapper.dtd"><mapper namespace="/"><resultMap id="JiKeUserMap" type="JiKeUser"><id property="id" column="id"/><result property="userName" column="userName"/><result property="password" column="password"/></resultMap><select id="selectUserMap" resultMap="JiKeUserMap">select * from jikeUser;</select><select id="selectUserList" resultType="JiKeUser" parameterType="JiKeUser">select * from jikebook.jikeuser;</select></mapper>

TestSelect.java

 package jike.book.test;import jike.book.pojo.JiKeUser;import org.apache.ibatis.io.Resources;import org.apache.ibatis.session.SqlSession;import org.apache.ibatis.session.SqlSessionFactory;import org.apache.ibatis.session.SqlSessionFactory;import org.apache.ibatis.session.SqlSessionFactoryBuilder;import java.io.IOException;import java.io.Reader;import java.util.List;/*** DateTime: 2016/9/5 21:45* Function: * Idea: */public class TestSelect {public static void main(String[] args) {// resource path String resource="jike/book/map/MyBatisConfig.xml";Reader reader=null;SqlSession session;try {reader= Resources.getResourceAsReader(resource);} catch ( IOException e ) {e.printStackTrace();}SqlSessionFactory sqlMapper=new SqlSessionFactoryBuilder().build(reader);session=sqlMapper.openSession();List<JiKeUser> list=session.selectList("selectUserMap");// List<JiKeUser> list=session.selectList("selectUserList");for(JiKeUser jiKeUser:list){System.out.println(jiKeUser.getUserName());}session.close();}}

run

 List<JiKeUser> list=session.selectList("selectUserMap");

or

 List<JiKeUser> list=session.selectList("selectUserList");

The results are all the same

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