主要有两个xml配置文件：sqlmapconfig.xml 、usermapper.xml

sqlmapconfig.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="druid.properties"></properties>
    <environments default="enviroment">
        <environment id="enviroment">
            <transactionManager type="JDBC"></transactionManager>
            <dataSource type="POOLED">
                <property name="driver" value="${jdbc.driver}"></property>
                <property name="url" value="${jdbc.url}"></property>
                <property name="username" value="${jdbc.username}"></property>
                <property name="password" value="${jdbc.password}"></property>
            </dataSource>
        </environment>
    </environments>
<mappers>
    <mapper resource="com/wocnz/dao/mapper/usermapper.xml"/>


</mappers>

</configuration>

usermapper.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.wocnz.dao.mapper.usermapper">

    <select id="getUserByID" resultType="com.wocnz.POJO.userdir" >
        SELECT * from user_dir
    </select>
<select id="selectUser" resultType="com.wocnz.POJO.user">
    select * from  user;
</select>

</mapper>



//测试代码
    @Test
    public void  test() throws Exception{
   
        InputStream in= Resources.getResourceAsStream("sqlmapconfig.xml");

        SqlSessionFactory sqlSessionFactory= new SqlSessionFactoryBuilder().build(in);
        //传入参数true，设置为事务自动提交
        SqlSession sqlSession = sqlSessionFactory.openSession(true);
        //全限定类名
        //List<user> objects = sqlSession.selectList("com.wocnz.dao.mapper.usermapper.selectUser");
        usermapper mapper = sqlSession.getMapper(usermapper.class);
        List<user> users = mapper.selectUser();
        System.out.println(users);
        sqlSession.close();
    }

使用sqlSession.selectList(“com.wocnz.dao.mapper.usermapper.selectUser”);需要传入全限定类名.id,id是mapper文件中的增删查改标签id
不传入全限定类名调用会报错

druid.properties

#mysql jdbc
jdbc.driver=com.mysql.cj.jdbc.Driver
jdbc.url=jdbc:mysql:///space?serverTimezone=UTC
jdbc.username=root
jdbc.password=123456

mybatis 默认的事务管理不是自动进行提交的，以下代码需要传入true

sqlSessionFactory.openSession(true);