java.lang.IllegalArgumentException: Mapped Statements collection does not contain value for org.fkit

报错信息：

Exception in thread "main" org.apache.ibatis.exceptions.PersistenceException:
### Error querying database. Cause: java.lang.IllegalArgumentException: Mapped Statements collection does not contain value for org.fkit.mapper.StudentMapper.selectStudent
### Cause: java.lang.IllegalArgumentException: Mapped Statements collection does not contain value for org.fkit.mapper.StudentMapper.selectStudent
at org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:26)
at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:111)
at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:102)
at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:98)
at org.fkit.test.SelectStudentTest.main(SelectStudentTest.java:12)
Caused by: java.lang.IllegalArgumentException: Mapped Statements collection does not contain value for org.fkit.mapper.StudentMapper.selectStudent
at org.apache.ibatis.session.Configuration$StrictMap.get(Configuration.java:797)
at org.apache.ibatis.session.Configuration.getMappedStatement(Configuration.java:631)
at org.apache.ibatis.session.Configuration.getMappedStatement(Configuration.java:624)
at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:107)
... 3 more

报错来源：在mybatis中进行查询时，运行代码报错误，错误的意思时：映射语句没有org.fkit.mapper.StudentMapper.selectStudent
在我的mybatis-config.xml中配置信息是： <mappers>
<mapper resource="org/fkit/mapper/UserMapper.xml"/>
</mappers>并没有配置StudentMapper的映射，所以在启动程序时，mybatis不知道去哪里找持久化类的映射文件了
正确的配置是： <mappers>
<mapper resource="org/fkit/mapper/UserMapper.xml"/>
<mapper resource="org/fkit/mapper/StudentMapper.xml"/>
</mappers>遇到这样的错误，不仅仅是映射文件没有配置，总的来说：
1、mapper.xml中没有加入namespace 

2、mapper.xml中的方法和接口mapper的方法不对应 

3、mapper.xml没有加入到mybatis-config.xml中(即总的配置文件)，例外：配置了mapper文件的包路径的除外 

4、mapper.xml文件名和所写的mapper名称不相同。