/*测试一级缓存(本地缓存):sqlSession的缓存级别。一级缓存是一直开启的 * 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。 * 以后如果需要获取相同的数据,直接从缓存中拿,不需要再去查数据库; * * 一级缓存失效情况: * 1、sqlSession不同 * 2、sqlSession相同,查询条件不同(当前一级缓存中还没有这个数据) * 3、sqlSession相同,两次查询之间执行了增删改操作(这次增删改可能对当前的数据有影响) * 4、sqlSession相同,手动清除了一级缓存(缓存清空)*/ @Test public void testFirstLevelCache1() throws IOException { String resource = "mybatis-config.xml"; InputStream inputStream = Resources.getResourceAsStream(resource); SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream); SqlSession sqlSession = sqlSessionFactory.openSession(); StudentMapper studentMapper = sqlSession.getMapper(StudentMapper.class); Student stu1 = studentMapper.getStuById(1); Student stu2 = studentMapper.getStuById(1); //此时stu2是直接从一级缓存中取出的,不会发出sql语句 System.out.println(stu1==stu2); sqlSession.close(); } @Test public void testFirstLevelCache2() throws IOException { String resource = "mybatis-config.xml"; InputStream inputStream = Resources.getResourceAsStream(resource); SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream); SqlSession sqlSession = sqlSessionFactory.openSession(); StudentMapper studentMapper = sqlSession.getMapper(StudentMapper.class); Student stu1 = studentMapper.getStuById(1); studentMapper.updateStu(new Student(2, "李四", new College(1))); Student stu2 = studentMapper.getStuById(1); //此时中间有增删改操作,会再次发出sql语句 System.out.println(stu1==stu2); sqlSession.close(); }