mybatis使用注解的时候，找不到映射：Type interface com.dao.UserDao is not known to the MapperRegistry.

最新推荐文章于 2023-10-18 15:48:58 发布

原创最新推荐文章于 2023-10-18 15:48:58 发布 · 940 阅读

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在使用 MyBatis 注解时遇到错误：找不到映射 Type interface com.dao.UserDao is not known to the MapperRegistry。尽管已在核心配置文件中指定接口路径，问题依旧存在。解决方案是在测试类启动代码中添加 factory.getConfiguration().addMapper(UserDao.class) 这一行，以注册注解文件，从而成功运行程序。

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今天按照视频来一步一步敲完之后，发现程序没有办法识别注解文件在哪个位置
但是我在mybatis核心配置文件中，已经说明了接口文件所在位置了，困扰了很久，最后终于找到答案；

<!--    指定接口所在位置-->
    <mappers>
        <package name="com.dao.UserDao"/>
    </mappers>

在核心配置文件中已经声明；

再看测试类中的启动代码

    public static void main(String[] args) throws IOException {
        InputStream inputStream = Resources.getResourceAsStream("SqlMapConfig.xml");
        SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(inputStream);

		//非常需要注意下面这一行代码，用来注册注解文件
       // factory.getConfiguration().addMapper(UserDao.class);
        SqlSession sqlSession = factory.openSession();
        UserDao userDao = sqlSession.getMapper(UserDao.class);
        List<User> users = userDao.findAll();
        for ( User user : users){
            System.out.println(user);
        }
        sqlSession.close();
        inputStream.close();

    }

这是原来的启动文件，使用它就会爆出错误：

log4j:WARN No appenders could be found for logger (org.apache.ibatis.logging.LogFactory).
log4j:WARN Please initialize the log4j system properly.
Exception in thread "main" org.apache.ibatis.binding.BindingException: Type interface com.dao.UserDao is not known to the MapperRegistry.
	at org.apache.ibatis.binding.MapperRegistry.getMapper(MapperRegistry.java:47)
	at org.apache.ibatis.session.Configuration.getMapper(Configuration.java:745)
	at org.apache.ibatis.session.defaults.DefaultSqlSession.getMapper(DefaultSqlSession.java:292)
	at com.MybatisTest.main(MybatisTest.java:29)

Process finished with exit code 1

原来必须要添加上这一行代码：！！！！！！！！！
factory.getConfiguration().addMapper(UserDao.class);
用来注册注解文件

即：

    public static void main(String[] args) throws IOException {
        InputStream inputStream = Resources.getResourceAsStream("SqlMapConfig.xml");
        SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(inputStream);


        factory.getConfiguration().addMapper(UserDao.class);
        SqlSession sqlSession = factory.openSession();
        UserDao userDao = sqlSession.getMapper(UserDao.class);
        List<User> users = userDao.findAll();
        for ( User user : users){
            System.out.println(user);
        }
        sqlSession.close();
        inputStream.close();

    }

最终成功运行：

log4j:WARN No appenders could be found for logger (org.apache.ibatis.logging.LogFactory).
log4j:WARN Please initialize the log4j system properly.
User{id=41, username='老王', birthday=Tue Feb 27 17:47:08 CST 2018, sex='男', address='北京'}
User{id=42, username='小二王', birthday=Fri Mar 02 15:09:37 CST 2018, sex='女', address='北京金燕龙'}
User{id=43, username='小san王', birthday=Sun Mar 04 11:34:34 CST 2018, sex='女', address='北京金燕龙'}
User{id=45, username='传智播客', birthday=Sun Mar 04 12:04:06 CST 2018, sex='男', address='北京金燕龙'}
User{id=46, username='老王', birthday=Wed Mar 07 17:37:26 CST 2018, sex='男', address='北京'}
User{id=48, username='小马宝莉', birthday=Thu Mar 08 11:44:00 CST 2018, sex='女', address='北京修正'}
User{id=54, username='nananna', birthday=Sat Aug 21 18:29:06 CST 2021, sex='n', address='666'}
User{id=55, username='nananna', birthday=Sun Aug 29 12:40:45 CST 2021, sex='n', address='666'}

Process finished with exit code 0