两张图彻底搞懂MyBatis的Mapper原理！

1@Test
2public void testSave() throws Exception {
3    //创建sessionFactory对象
4    SqlSessionFactory sf = new SqlSessionFactoryBuilder().
5            build(Resources.getResourceAsStream("mybatis-config.xml"));
6    //获取session对象
7    SqlSession session = sf.openSession();
8    //创建实体对象
9    User user = new User();
10    user.setUsername("toby");
11    user.setPassword("123");
12    user.setAge(23);
13    //保存数据到数据库中
14    session.insert("com.toby.mybatis.domain.UserMapper.add", user);
15    //提交事务,这个是必须要的,否则即使sql发了也保存不到数据库中
16    session.commit();
17    //关闭资源
18    session.close();
19}

1<mapper namespace="com.toby.mybatis.domain.UserMapper">
2    <!--#{}在传入的对象中找对应的属性值-->
3    <!--parameterType传入的参数是什么类型-->
4    <insert id="add" parameterType="com.toby.mybatis.domain.User">
5        INSERT INTO USER (username,password,age) VALUES (#{username},#{password},#{age})
6    </insert>
7</mapper>

1public void testGetObject() throws Exception {
2    SqlSession session = MybatisUtil.openSession();
3
4    UserMapper mapper = session.getMapper(UserMapper.class);
5    User user = mapper.get(5L);
6
7    System.out.println(user);
8    session.close();
9}

1public interface UserMapper {
2
3    public void add(User user);
4    public User get(Long id);
5}