public interface MemberMapperCache {

    public Members selectMembersById(Integer id);

}

public class Members implements Serializable {

    private static final long serialVersionUID = 1L;

    private Integer id;

    private String member_name;

    private Integer age;

    private Integer gender;

    private String email;

    public Members() {}

    public Members(Integer id, String member_name, Integer age, Integer gender, String email) {

        super();

        this.id = id;

        this.member_name = member_name;

        this.age = age;

        this.gender = gender;

        this.email = email;

    }

    public Integer getId() {

        return id;

    }

    public String getMember_name() {

        return member_name;

    }

    public Integer getAge() {

        return age;

    }

    public Integer getGender() {

        return gender;

    }

    public String getEmail() {

        return email;

    }

    public void setId(Integer id) {

        this.id = id;

    }

    public void setMember_name(String member_name) {

        this.member_name = member_name;

    }

    public void setAge(Integer age) {

        this.age = age;

    }

    public void setGender(Integer gender) {

        this.gender = gender;

    }

    public void setEmail(String email) {

        this.email = email;

    }

    @Override

    public String toString() {

        return "Members [id=" + id + ", member_name=" + member_name + ", age=" + age + ", gender=" + gender + ", email=" + email + "]";

    }

}

<?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">

    <!--

        eviction:缓存的回收策略

            LRU:最近最少使用的,移除最长时间不被使用的对象

            FIFO:先进先出,按对象进入缓存的顺序来移除他们

            SOFT:软引用,移除基于垃圾回收器状态和软引用规则的对象

            WEAK:弱引用,更积极的移除基于垃圾收集器状态和弱引用规则的对象

            默认是LRU

        flushInterval:缓存刷新间隔

            默认不清空

        readOnly:是否只读

            true:只读:mybatis认为所有从缓存中获取数据的操作都是只读操作,不会修改数据

                mybatis为了加快获取速度,直接将数据在缓存中的引用交给用户,不安全,但是速度快

            false:非只读:mybatis觉得获取的数据可能会被修改,并会用序列化和反序列化技术克隆一份新的数据

                再给用户,这样安全,但是速度相对慢

                默认false,非只读

        size:缓存中存放多少个元素

        type:自定义缓存,实现Cache接口集合,type="全类名"

        ===>POJO必须实现序列化接口

     -->

    <cache eviction="LRU" flushInterval="60000" readOnly="false" size="1024"></cache>

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

        select * from members where id = #{id}

    </select>

</mapper>

    <settings>

        <!-- 打印log日志 -->

        <setting name="logImpl" value="STDOUT_LOGGING"/>

        <!-- 开启二级缓存 -->

        <setting name="cacheEnabled" value="true"/>

    </settings>

    /**

     * Mybatis的缓存机制

     * 二级缓存:

     *         1.在全局配置文件中开启二级缓存

     *         2.在mapper.xml文件中加入<cache><cache/>标签

     *         3.POJO实现序列化接口

     */

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

        // 获取两个不同的session

        SqlSession session1 = getSqlSession();

        SqlSession session2 = getSqlSession();

        try {

            // 获取两个不同的mapper

            MemberMapperCache mapper1 = session1.getMapper(MemberMapperCache.class);

            MemberMapperCache mapper2 = session2.getMapper(MemberMapperCache.class);

            // 获取id为1的对象

            Members member1 = mapper1.selectMembersById(1);

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

            session1.close();

            // 获取id为1的对象

            Members member2 = mapper2.selectMembersById(1);

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

            session2.close();

        } finally {

        }

    }

    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;

    }