在resource包下面的两个配置文件

mybatis-config.xml:

<!--
数据库的信息
-->
<?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>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql:///student?useSSL=false"/>
                <property name="username" value="root"/>
                <property name="password" value="a1b2c3"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="usermapper.xml"/>
    </mappers>
</configuration>


usermapper.xml:

<!--
写sql语句的
-->
<?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="test">
    <select id="selectAll" resultType="it.student">
        select * from student;
    </select>
</mapper>






test:

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 java.io.IOException;
import java.io.InputStream;
import java.util.List;

public class test {
    public static void main(String[] args) throws IOException {
        //加载mybatis核心配置文件，获取sqlSession
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

        //获取对象
        SqlSession sqlSession = sqlSessionFactory.openSession();

        //执行sql
        List<Object> objects = sqlSession.selectList("test.selectAll");
   System.out.println(objects);
   sqlSession.close();
    }
}