一级缓存（默认开始sqlsession级别）和二级缓存(testTwoCache)

我会带着你远行 2024-04-03 07:21 53阅读 0赞

### 一级缓存（默认开始sqlsession级别） ###

####    一级缓存失效的四种情况：   1.不同的sqlsession对应不同的缓存   2.同一个sqlsession但是查询条件不同   3.同一个sqlsession两次查询期间执行了任何一个增删改的操作(testgetEmpByEid3)   4.同一个sqlsession两次查询期间手动清空了缓存 ####

@Test
        public void getEmpByEmpIdTest(){
            SqlSession sqlSession1 = SqlSessionUtil.getSqlSession();
            CacheMapper mapper1 = sqlSession1.getMapper(CacheMapper.class);
            //此处用的是同一个Sqlsession
            Emp emp1 = mapper1.getEmpByEmpId(1);//第一条emp1
            System.out.println(emp1);
            Emp emp2 = mapper1.getEmpByEmpId(1);//第二条emp2
            System.out.println(emp2);
        }

一级缓存失效情况

@Test
        public void testgetEmpByEid2(){
            SqlSession sqlsession1 = SQLsession.getSqlsession();
            CacheMapper mapper1 = sqlsession1.getMapper(CacheMapper.class);
            Emp empByEid1 = mapper1.getEmpByEid(1);
            System.out.println(empByEid1);
            SqlSession sqlsession2 = SQLsession.getSqlsession();
            CacheMapper mapper2 = sqlsession2.getMapper(CacheMapper.class);
            Emp empByEid2 = mapper2.getEmpByEid(1);
            System.out.println(empByEid2);
        }

@Test
        public void testgetEmpByEid3(){
            SqlSession sqlsession = SQLsession.getSqlsession();
            CacheMapper mapper = sqlsession.getMapper(CacheMapper.class);
            Emp empByEid1 = mapper.getEmpByEid(1);
            System.out.println(empByEid1);
            mapper.insertEmp(new Emp(null,"sdd",12,"1","1",null));
            Emp empByEid2 = mapper.getEmpByEid(1);
            System.out.println(empByEid2);
        }

@Test
        public void testTwoCache(){
            //不能使用工具类的形式创建SQLsession
            try {
               InputStream in = Resources.getResourceAsStream("mybatis-config.xml");
                SqlSessionFactory builder = new SqlSessionFactoryBuilder().build(in);
                SqlSession sqlSession1 = builder.openSession(true);
                CacheMapper mapper1 = sqlSession1.getMapper(CacheMapper.class);
                System.out.println(mapper1.getEmpByEid(1));
                sqlSession1.close();
                SqlSession sqlSession2 = builder.openSession(true);
                CacheMapper mapper2 = sqlSession2.getMapper(CacheMapper.class);
                System.out.println(mapper2.getEmpByEid(1));
                sqlSession2.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
    
    
        }

### 二级缓存(testTwoCache) ###

####    1.在核心配置文件中设置全局配置属性cacheEnabled="ture"，默认为ture不需要设置   2.在映射文件中配置标签<cache/>   3.二级缓存必须在sqlSession关闭或提交后有效   4.查询的数据所转换的实体类类型必须实现序列化的接口(implements Serializable )   二级缓存失效的情况：   两次查询中间执行了任意的增删改查，会使一级缓存和二级缓存同时失效 ####