测试类

 @Test
    public void testMyBatis() throws IOException {
        //加载核心配置文件
        InputStream is = Resources.getResourceAsStream("mybatis-config.xml");
        //获取SqlSessionFactoryBuilder
        SqlSessionFactoryBuilder sqlSessionFactoryBuilder = new SqlSessionFactoryBuilder();
        //获取sqlSessionFactory
        SqlSessionFactory sqlSessionFactory = sqlSessionFactoryBuilder.build(is);
        //获取SqlSession
        SqlSession sqlSession = sqlSessionFactory.openSession(true);
        //获取mapper接口对象,帮助创建这个UserMapper的实现类，返回实现类对象
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        //测试功能
        int result = mapper.insertUser();
        //提交事务
        //sqlSession.commit();
        System.out.println("result:"+result);
    }

MyBatis框架在底层基于mapper接口动态创建实现类

        //获取mapper接口对象,帮助创建这个UserMapper的实现类，返回实现类对象
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);