Spring Boot 2.0 新人会踩的坑--启动报404错误

转载自：http://www.javaman.cn/channels/sb2

启动程序，验证效果

根据图示，点击按钮，来启动 Spring Boot Web 程序, 查看控制台输出：

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v2.1.4.RELEASE)

2019-04-14 19:57:59.795  INFO 3680 --- [           main] com.example.demo.DemoApplication         : Starting DemoApplication on 192.168.0.100 with PID 3680 (/Users/a123123/Work/IdeaProjects/demo/target/classes started by allen-jiang in /Users/a123123/Work/IdeaProjects/demo)
2019-04-14 19:57:59.798  INFO 3680 --- [           main] com.example.demo.DemoApplication         : No active profile set, falling back to default profiles: default
2019-04-14 19:58:00.666  INFO 3680 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8080 (http)
2019-04-14 19:58:00.689  INFO 3680 --- [           main] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2019-04-14 19:58:00.689  INFO 3680 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet engine: [Apache Tomcat/9.0.17]
2019-04-14 19:58:00.756  INFO 3680 --- [           main] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2019-04-14 19:58:00.757  INFO 3680 --- [           main] o.s.web.context.ContextLoader            : Root WebApplicationContext: initialization completed in 920 ms
2019-04-14 19:58:00.978  INFO 3680 --- [           main] o.s.s.concurrent.ThreadPoolTaskExecutor  : Initializing ExecutorService 'applicationTaskExecutor'
2019-04-14 19:58:01.183  INFO 3680 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8080 (http) with context path ''
2019-04-14 19:58:01.186  INFO 3680 --- [           main] com.example.demo.DemoApplication         : Started DemoApplication in 1.678 seconds (JVM running for 2.176)
当控制台日志中输出了 Tomcat started on port(s): 8888 (http) with context path ''时，表示内嵌的 Tomcat 容器已经启动成功了，端口为 8080 ！

接下来，我们在浏览器上访问 http://localhost:8888/hello 接口，验证一下，接口是否能够正常访问：

返回了我们想要的 Hello, Spring Boot ! 字符串，接口访问正常，大工告成！

SpringbootApplication.png

注意！！！: @SpringBootApplication注解的类必须要放在包扫描的最外层才可以。

否则页面会报404错误。

四、总结
本文中，我们首先了解了什么是 Spring Boot, 以及Spring Boot 的相关特性，最后我们手把手学习了如何搭建一个 Spring Boot 项目，并编写了第一个接口且访问成功。

通过实际操作，真切地感受到了 Spring Boot 的魅力所在！老铁，双击 666！