MyBatis的一级缓存

什么是缓存？

把当前查询出来的数据进行记录，下一次查询相同数据时，从缓存中去取，就不会重新访问数据库了

MyBatis的缓存分为一级缓存和二级缓存

一级缓存默认是开启的

缓存只针对查询功能有效

CacheMapper

CacheMapper.xml

测试

package com.baidu.mybatis;importcom.baidu.mybatis.mapper.CacheMapper;importcom.baidu.mybatis.pojo.Emp;importcom.baidu.mybatis.utils.SqlSessionUtils;importorg.apache.ibatis.session.SqlSession;importorg.junit.Test;publicclassCacheMapperTest{@TestpublicvoidtestCache(){SqlSessionsqlSession=SqlSessionUtils.getSqlSession();SqlSessionsqlSession2=SqlSessionUtils.getSqlSession();CacheMappermapper=sqlSession.getMapper(CacheMapper.class);Empemp=mapper.getEmpByEid(1);Empemp2=mapper.getEmpByEid(1);System.out.println("emp = "+emp);System.out.println("emp2 = "+emp2);System.out.println("--------------------");CacheMappermapper1=sqlSession.getMapper(CacheMapper.class);Empemp3=mapper1.getEmpByEid(1);Empemp4=mapper1.getEmpByEid(1);System.out.println("emp3 = "+emp3);System.out.println("emp4 = "+emp4);System.out.println("------------------------");CacheMappermapper2=sqlSession2.getMapper(CacheMapper.class);Empemp5=mapper2.getEmpByEid(1);Empemp6=mapper2.getEmpByEid(1);System.out.println("emp5 = "+emp5);System.out.println("emp6 = "+emp6);}}

可以看到不同sqlsession，才会输出sql语句