java.lang.TypeNotPresentException: Type [unknown] not present错误

MapperScan所需要的包导入错误
应该导入org.mybatis.spring.annotation下的MapperScan

这里就要注意 mybatis导入的依赖是

mybatis-spring-boot-starter  

也就是

 <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.1.1</version>
</dependency>