XML方式的配置实现插入数据是自动获取插入数据的ID值并封装到Bean对象中

 <insert id="add" parameterType="com.itheima.domain.User">
        <selectKey keyProperty="id" keyColumn="id"  order="AFTER" resultType="int">
            select last_insert_id()
        </selectKey>
        insert into user(username,birthday,sex,address)values (#{username},null,'男','xian')
    </insert>

test测试

Bean对象的id属性就不需要手动去set了 配置了上面的代码就会自动从数据库获取并封装到Bean的id属性中

public static void main(String[] args) throws Exception {

        InputStream in = Resources.getResourceAsStream("mybatis.xml");
        SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
        SqlSessionFactory s = builder.build(in);
        SqlSession sqlSession = s.openSession();

        //通过SqlSession创建Dao接口的代理对象
        IUserDao userdao = sqlSession.getMapper(IUserDao.class);

        User uu = new User();
        uu.setUsername("hhaaaah2");
        System.out.println(uu+"保存前");
        userdao.add(uu);
        sqlSession.commit();

        System.out.println(uu+"保存后");