最近，在参与某spring boot 为基础的项目框架，前几天还无问题，最近一直在报如下错误。
用外部Tomcat启动或者部署无问题。用Application 主方法启动报错。
Error starting ApplicationContext. To display the auto-configuration report re-run your application with 'debug' enabled.
2019-10-25 17:49:17.091 ERROR 24280 --- [ main] o.s.boot.SpringApplication : Application startup failed
org.springframework.context.ApplicationContextException: Unable to start embedded container; nested exception is org.springframework.context.ApplicationContextException: Unable to start EmbeddedWebApplicationContext due to missing EmbeddedServletContainerFactory bean.
at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.onRefresh(EmbeddedWebApplicationContext.java:137) ~[spring-boot-1.5.7.RELEASE.jar:1.5.7.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:537) ~[spring-context-4.3.9.RELEASE.jar:4.3.9.RELEASE]
at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:122) ~[spring-boot-1.5.7.RELEASE.jar:1.5.7.RELEASE]
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:693) [spring-boot-1.5.7.RELEASE.jar:1.5.7.RELEASE]
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:360) [spring-boot-1.5.7.RELEASE.jar:1.5.7.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:303) [spring-boot-1.5.7.RELEASE.jar:1.5.7.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1118) [spring-boot-1.5.7.RELEASE.jar:1.5.7.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1107) [spring-boot-1.5.7.RELEASE.jar:1.5.7.RELEASE]
at com.Application.main(Application.java:26) [classes/:na]
Caused by: org.springframework.context.ApplicationContextException: Unable to start EmbeddedWebApplicationContext due to missing EmbeddedServletContainerFactory bean.
at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.getEmbeddedServletContainerFactory(EmbeddedWebApplicationContext.java:189) ~[spring-boot-1.5.7.RELEASE.jar:1.5.7.RELEASE]
at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.createEmbeddedServletContainer(EmbeddedWebApplicationContext.java:162) ~[spring-boot-1.5.7.RELEASE.jar:1.5.7.RELEASE]
at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.onRefresh(EmbeddedWebApplicationContext.java:134) ~[spring-boot-1.5.7.RELEASE.jar:1.5.7.RELEASE]
... 8 common frames omitted
解决方法：
①确定POM文件中是否引入spring boot 内置的tomcat 启动器。
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-tomcat</artifactId>
<scope>provided</scope>
</dependency>
②如果有，请确定在创建启动Application程序时，必要的选项是否选择？如下图
③如果以上还出现错误，请 spring boot Application 主程序命令进行启动
