主要原因是bean没有注册上，
推荐方法：主程序 XXXApplication加上@MapperScan(“com.xxx.mapper”)。
其他方法：只要在对应POJP加上 @Component就好
主要错误：
Field newsMapper in com.news.service.NewsService required a bean of type ‘com.news.mapper.NewsMapper’ that could not be found.
- @org.springframework.beans.factory.annotation.Autowired(required=true)
java.lang.Object.wait(Native Method)
java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:143)
com.mysql.jdbc.AbandonedConnectionCleanupThread.run(AbandonedConnectionCleanupThread.java:43)
2020-01-20 14:23:25.528 INFO 10764 --- [ restartedMain] ConditionEvaluationReportLoggingListener :
Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
2020-01-20 14:23:25.691 ERROR 10764 --- [ restartedMain] o.s.b.d.LoggingFailureAnalysisReporter :
***************************
APPLICATION FAILED TO START
***************************
Description:
Field newsMapper in com.news.service.NewsService required a bean of type 'com.news.mapper.NewsMapper' that could not be found.
The injection point has the following annotations:
- @org.springframework.beans.factory.annotation.Autowired(required=true)
Action:
Consider defining a bean of type 'com.news.mapper.NewsMapper' in your configuration.
Process finished with exit code 0