Mybatis出现：org.apache.ibatis.binding.BindingException: Type interface com.niuyun.dao.UserDao is not known to the MapperRegistry.的错误，如何解决？
错误如下：
类型接口dao不知道mapper注册中心点的问题
org.apache.ibatis.binding.BindingException: Type interface com.niuyun.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.haroro.test.AccountTest.init(AccountTest.java:40)
! 很明显是没有注册映射的路径
- 查看MyBatis中xml配置文件，其中系统的核心设置
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
<environments default="development">
<environment id="development">
<transactionManager type="JDBC"/>
<dataSource type="POOLED">
<property name="driver" value="${driver}"/>
<property name="url" value="${url}"/>
<property name="username" value="${username}"/>
<property name="password" value="${password}"/>
</dataSource>
</environment>
</environments>
</configuration>
- 发现确实少了映射的路径配置，将其加上
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
<environments default="development">
<environment id="development">
<transactionManager type="JDBC"/>
<dataSource type="POOLED">
<property name="driver" value="${driver}"/>
<property name="url" value="${url}"/>
<property name="username" value="${username}"/>
<property name="password" value="${password}"/>
</dataSource>
</environment>
</environments>
<!--映射的路径-->
<mappers>
<mapper resource="org/mybatis/example/BlogMapper.xml"/>
</mappers>
</configuration>
- 如果改正后还是出现同样的问题，那么要去看映射路径的.xml文件，其中查看"namespace"的类名是否正确，不正确就改正
<!--名字命名空间--><!--如果使用的是mapper接口的形式， 则namespace 写的就是接口的全类名-->
<mapper namespace="com.qianfeng.dao.UserDao">
<!--resultType 返回值的结果的类型--><!--#{id} 占位符，相当于 ？-->
<select id="getOne" resultType="com.qianfeng.entity.User">
select * from user where id = #{id}
</select>
</mapper>
- 问题解决，可以运行
~希望可以帮助到您，解决问题