public interface MemberMapperCache {

    public Members selectMembersById(Integer id);

}

<?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.dao.MemberMapperCache">

    <select id="selectMembersById" resultType="members">

        select * from members where id = #{id}

    </select>

</mapper>

    /**

     * Mybatis的缓存机制

     * 一级缓存(本地缓存)也叫sqlSession级别的缓存:与数据库同一次会话期间查询到的数据会放在本地缓存中,以后再获取相同的数据就没必要再去数据库中拿了

     *         一级缓存失效的4种情况

     *         1.sqlSession不同

     *         2.sqlSession相同但是查询条件不同(很好理解)

     *         3.sqlSession相同但是两次查询之间掺杂了相同数据的增删改操作

     *         4.sqlSession相同但是两次查询之间清除了缓存(session.clearCache();)

     */

    public static void main(String[] args) throws IOException {

        SqlSession session = getSqlSession();

        try {

            // 面向接口方式

            MemberMapperCache mapper = session.getMapper(MemberMapperCache.class);

            Members member1 = mapper.selectMembersById(1);

            Members member2 = mapper.selectMembersById(2);

            System.out.println(member1.toString());

            System.out.println(member2.toString());

            session.commit();

        } finally {

            // 关闭session

            session.close();

        }

    }

    public static SqlSession getSqlSession() throws IOException {

        // 读取全局配置文件

        String resource = "conf/mybatis-config.xml";

        InputStream inputStream = Resources.getResourceAsStream(resource);

        // 获取sqlSessionFactory对象

        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

        // 打开session

        SqlSession session = sqlSessionFactory.openSession();

        return session;

    }

==>  Preparing: select * from members where id = ?

==> Parameters: 1(Integer)

<==    Columns: id, member_name, pass_word, age

<==        Row: 1, 张三, 123456, 25

<==      Total: 1

Member [id=1, member_name=张三, password=123456, age=25]

Member [id=1, member_name=张三, password=123456, age=25]

            MemberMapperCache mapper = session.getMapper(MemberMapperCache.class);

            Members member1 = mapper.selectMembersById(1);

            session.clearCache();

            Members member2 = mapper.selectMembersById(1);

            System.out.println(member1.toString());

            System.out.println(member2.toString());

==>  Preparing: select * from members where id = ?

==> Parameters: 1(Integer)

<==    Columns: id, member_name, pass_word, age

<==        Row: 1, 张三, 123456, 25

<==      Total: 1

==>  Preparing: select * from members where id = ?

==> Parameters: 1(Integer)

<==    Columns: id, member_name, pass_word, age

<==        Row: 1, 张三, 123456, 25

<==      Total: 1

Member [id=1, member_name=张三, password=123456, age=25]

Member [id=1, member_name=张三, password=123456, age=25]