问题：
Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
2019-06-01 15:47:30.708 ERROR 18576 --- [ restartedMain] o.s.boot.SpringApplication : Application run failed
Caused by: org.springframework.context.ApplicationContextException: Unable to start ServletWebServerApplicationContext due to missing ServletWebServerFactory bean.
解决办法：
改为