mybatis二级缓存案例

<mapper namespace="com.cn.dao.GoodsDao">
    <!--开启二级缓存-->
    <cache></cache>

    //二级缓存
    @Test
    public void testSelGoodsByGid2(){
        //通过工具类获取第一个sqlSession对象
        SqlSession session1 = SessionUtils.getSession();
        GoodsDao mapper1 = session1.getMapper(GoodsDao.class);
        Goods goods1 = mapper1.selGoodsByGid(4);
        System.out.println(goods1);
        //关闭或提交第一个会话，第一个会话的数据就会被保存到二级缓存中去
//        session1.close();
        session1.commit();
        System.out.println("------------");
        //通过工具类获取第二个sqlSession对象
        SqlSession session2 = SessionUtils.getSession();
        GoodsDao mapper2 = session2.getMapper(GoodsDao.class);
        //因为开启了二级缓存，会从二级缓存中查询数据，查询到了数据，就不会执行sql语句
        Goods goods2 = mapper2.selGoodsByGid(4);
        System.out.println(goods2);
    }

DEBUG [main] - ==>  Preparing: select * from t_goods WHERE gid = ? 
DEBUG [main] - ==> Parameters: 4(Integer)
DEBUG [main] - <==      Total: 1
Goods{gid=4, gname='冰箱', gprice=3155.55, gcount=30, gdate=Sat Aug 15 00:00:00 CST 2020}
DEBUG [main] - Resetting autocommit to true on JDBC Connection [com.mysql.jdbc.JDBC4Connection@2d2e5f00]
DEBUG [main] - Closing JDBC Connection [com.mysql.jdbc.JDBC4Connection@2d2e5f00]
DEBUG [main] - Returned connection 758013696 to pool.
------------
DEBUG [main] - Cache Hit Ratio [com.cn.dao.GoodsDao]: 0.5
Goods{gid=4, gname='冰箱', gprice=3155.55, gcount=30, gdate=Sat Aug 15 00:00:00 CST 2020}