初学SpringBoot，此过程中遇到各种问题，这里做记录，以防后面忘记了
1.要运行的application类启动时报：
org.springframework.context.ApplicationContextException: Unable to start web server; nested exception is org.springframework.context.ApplicationContextException: Unable to start ServletWebServerApplicationContext due to missing ServletWebServerFactory bean.
at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.onRefresh(ServletWebServerApplicationContext.java:155) ~[spring-boot-2.0.3.RELEASE.jar:2.0.3.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:544) ~[spring-context-5.0.7.RELEASE.jar:5.0.7.RELEASE]
at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:140) ~[spring-boot-2.0.3.RELEASE.jar:2.0.3.RELEASE]
解决方案：
未给要运行的application class添加注解 @EnableAutoConfiguration，再次启动没有该错误
2.访问 http://localhost:8080/hello 页面报错：
Whitelabel Error Page
This application has no explicit mapping for /error, so you are seeing this as a fallback.
Thu Jun 28 10:42:48 CST 2018
There was an unexpected error (type=Internal Server Error, status=500).
Error resolving template "hello springboot", template might not exist or might not be accessible by any of the configured Template Resolvers
错误原因：由于application类使用了注解@Controller，而使用@Controller注解时需要有对应的页面存在，如jsp/html等，所以解决方式有如下两种：
a.将注解@Controller换成 @RestController，再次访问没有该错误
b.在templates下添加一页面，如下图
