Field adminMapper in com.course.service.impl.AdminServiceImpl required a bean of type 'com.course.mapper.AdminMapper' that could not be found

Field adminMapper in com.course.service.impl.AdminServiceImpl required a bean of type 'com.course.mapper.AdminMapper' that could not be found.

mybatis-plus版本由3.1.2升级至3.4.0后，重新运行就报了错了

2021-10-30 16:47:03.148 ERROR 17576 --- [  restartedMain] o.s.b.d.LoggingFailureAnalysisReporter   : 
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APPLICATION FAILED TO START
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Description:

Field adminMapper in com.course.service.impl.AdminServiceImpl required a bean of type 'com.course.mapper.AdminMapper' that could not be found.

Action:
Consider defining a bean of type 'com.course.mapper.AdminMapper' in your configuration.
Process finished with exit code 0

分析一下： adminMapper是列表中最先的一个mapper, 推测 @Mapper注解失效 ，尝试使用@MapperScan注解，发现正常运行了（PS，加了@MapperScan，@Mapper就没必要了）

@MapperScan("com.course.mapper")