mybatis使用注解开发时报错：Type interface com.dao.UserMapper is not known to the MapperRegistry.

第二次编辑：

离大谱就，出现这个错的根本原因是我的加载映射文件写错了包的位置，本来加载映射已经在sqlMapConfig.xml文件中配置完了，但因为我配置的路径错误，导致我下一个查询时也出了很多错误，检查了一个早上，都没找到错误在哪，刚刚不知道咋又看了一遍，突然发现包路径错误

 之前写的包一直是com.mapper，但是基本的查询也能查询出来，是因为之前其他模块内都写了，直到使用复杂的就查不出来了，一直找不到原因

劝诫：一定要看对自己的包位置！！！

报错内容：

org.apache.ibatis.binding.BindingException: Type interface com.dao.UserMapper 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:779)
    at org.apache.ibatis.session.defaults.DefaultSqlSession.getMapper(DefaultSqlSession.java:291)
    at com.test.MapperTest.before(MapperTest.java:32)

项目目录：

 UserMapper接口：

public interface UserMapper {

    @Insert("insert into user values (#{id},#{username},#{password},#{birthday})")
    public void save(User user);

    @Update("update user set username = #{username} ,password = #{password} where id = #{id}")
    public void update(User user);

    @Delete("delete from user where id = #{id}")
    public void delete(int id);

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

    @Select("select * from user")
    public List<User> findAll();
}

测试代码：

public class MapperTest {

    private UserMapper mapper = null;

    private SqlSession sqlSession = null;

    @Before
    public void before() throws IOException {
        InputStream resourceAsStream = Resources.getResourceAsStream("sqlMapConfig.xml");
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(resourceAsStream);
//        sqlSessionFactory.getConfiguration().addMapper(UserMapper.class);
        sqlSession = sqlSessionFactory.openSession(true);
        mapper = sqlSession.getMapper(UserMapper.class);


    }

    @Test
    public void save() throws IOException {
        User user = new User();
        user.setUsername("nihao");
        user.setPassword("123456");
        mapper.save(user);
    }

    @Test
    public void update(){
        User user = new User();
        user.setId(1);
        user.setUsername("zhanzhan");
        user.setPassword("fhg");
        mapper.update(user);
    }

    @Test
    public void delete(){
        mapper.delete(2);
    }

    @Test
    public void findById(){
        User user = mapper.findById(1);
        System.out.println(user);
    }

    @Test
    public void findAll(){
        List<User> userList = mapper.findAll();
        for (User user : userList) {
            System.out.println(user);
        }
    }


    @After
    public void after(){
        sqlSession.close();
    }

}

报错原因：

　　写完接口类之后没有让mybatis注册这个类

解决办法：

　　在生成sqlSession工厂之后加入如下代码：

sqlSessionFactory.getConfiguration().addMapper(UserMapper.class);