Mybatis有四个核心组件:
SqlSessionFactoryBuilder(构造器):根据代码或者配置生成SqlSessionFactory.
来看我们第一个项目的工具类中的一段代码,getSessionFactory()方法用于返回一个SqlSessionFactory对象,而且是通过SqlSessionFactoryBuilder().build(inputStream)方式构建的.

public static SqlSessionFactory getSessionFactory() throws IOException {
        String resource ="mybatis.cfg.xml";//配置文件
        InputStream inputStream=Resources.getResourceAsStream(resource);
        SqlSessionFactory sessionFactory=new SqlSessionFactoryBuilder().build(inputStream);
        return sessionFactory;
    }

SqlSessionFactory(工厂接口):依靠其来生成SqlSession,使用的是工厂模式.通过openSession()方法生成一个sqlSession对象.

public static SqlSession getSession() throws IOException {
        SqlSessionFactory sessionFactory=getSessionFactory();
        return sessionFactory.openSession();
    }

SqlSession(会话):一个既可以发送SQL执行返回结果,也可以获取Mapper的接口.
顺便这几天刚好学了JUnit写几个测试.

public class TestMybatis {
    SqlSession sqlSession;
    UserMapper mapper;
    @Before
    public void getMapper() throws IOException {
        sqlSession=MybatisUtil.getSession();
        mapper=sqlSession.getMapper(UserMapper.class);
    }
    @Test
    public void getUserTest() {
        User user=mapper.getUser(1);
        System.out.println(user.getId()+"    "+user.getName());
    }
    @Test
    public void addUserTest() {
        User user=new User();
        user.setName("saber");
        mapper.insertUser(user);

    }
    @Test
    public void updateUserTest() {
        User user=new User();
        user.setName("lance");
        user.setId(2);
        mapper.updateUser(user);

    }
    @Test
    public void deleteUserTest() {
        mapper.deleteUser(3);

    }
    @After
    public void close() {
        sqlSession.commit();//不要忘记提交  
        sqlSession.close();
    }
}

来看运行结果

测试结果

public interface UserMapper2 {
    @Select("select * from user where id = #{id}")
    public User getUser(int id);

    @Insert("insert into user(id,name) values(#{id},#{name})")
    public User insertUser(User user);
    
    @Delete("delete from user where id = #{id}")
    public int deleteUser(Integer id);
    
    @Update("update user set name=#{name} where id = #{id}")
    public int updateUser(User user);
}