Mybatis-Dao层实现（通过代理方式）

1.代理方式开发是主流
2.Mapper接口开发方法只需要编写Mapper接口（相当于Dao接口）,然后由Mybatis根据接口创建动态代理对象
Mapper接口开发需要遵循以下规范
一一对应

UserMapper.xml

<!--    根据id查询-->
    <select id="findById" parameterType="int" resultType="user">
        select * from user where id=#{id}
    </select>

UserMapper接口(dao层)

public User findById(int Id);

ServiceTest类

public class ServiceTest {
    public static void main(String[] args) throws IOException {
        InputStream stream = Resources.getResourceAsStream("SqlMapConfig.xml");
        SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(stream);
        SqlSession sqlSession = factory.openSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        User user = mapper.findById(1);
        System.out.println(user);
    }
}