錯誤描述：啟動沒問題無報錯
訪問URL信息如下：
Whitelabel Error Page
This application has no explicit mapping for /error, so you are seeing this as a fallback.
Tue Oct 26 09:40:52 CST 2021
There was an unexpected error (type=Not Found, status=404).
控制台信息：
2021-10-26 09:40:51.965 INFO 644 --- [nio-8080-exec-1] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring DispatcherServlet 'dispatcherServlet'
2021-10-26 09:40:51.965 INFO 644 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet : Initializing Servlet 'dispatcherServlet'
2021-10-26 09:40:51.965 INFO 644 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet : Completed initialization in 0 ms
錯誤原因：
SpringBoot的啟動類路徑問題
SpringBoot的啟動類要和Controller同級或在Controller上級