mybatis异常： Error querying database. Cause: java.sql.SQLException: Error setting driver on UnpooledD

刚学mybatis遇到异常
Exception in thread “main” org.apache.ibatis.exceptions.PersistenceException:

### Error querying database.  Cause: java.sql.SQLException: Error setting driver on UnpooledDataSource. Cause: java.lang.ClassNotFoundException: Cannot find class: com.mysql.jdbc.driver
### The error may exist in com/chenx/dao/StudentDao.xml
### The error may involve com.chenx.dao.StudentDao.selectStudents
### The error occurred while executing a query

百度查看后面发现是

应当改为

但是改完之后仍然报错，查找了很久没有找到解决方案
最后发现，是我的maven本地仓库没有mysql相关的包
在maven的pom.xml的dependencies标签里加上

    
    
      mysql
      mysql-connector-java
      5.1.37
    

重新加载maven再编译即可