在搭建eureka服务端时，配置依赖都没问题，结果报了StandardEngine[Tomcat].StandardHost[localhost].TomcatEmbeddedContext[] failed to start
详细如下：

org.springframework.context.ApplicationContextException: Unable to start web server; nested exception is org.springframework.boot.web.server.WebServerException: Unable to start embedded Tomcat
	at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.onRefresh(ServletWebServerApplicationContext.java:155) ~[spring-boot-2.1.0.RELEASE.jar:2.1.0.RELEASE]
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:540) ~[spring-context-5.1.2.RELEASE.jar:5.1.2.RELEASE]
	at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:140) ~[spring-boot-2.1.0.RELEASE.jar:2.1.0.RELEASE]
	at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:775) ~[spring-boot-2.1.0.RELEASE.jar:2.1.0.RELEASE]
	at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397) ~[spring-boot-2.1.0.RELEASE.jar:2.1.0.RELEASE]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:316) ~[spring-boot-2.1.0.RELEASE.jar:2.1.0.RELEASE]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1260) ~[spring-boot-2.1.0.RELEASE.jar:2.1.0.RELEASE]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1248) ~[spring-boot-2.1.0.RELEASE.jar:2.1.0.RELEASE]
	at com.itheima.eureka.EurekaApp.main(EurekaApp.java:16) ~[classes/:na]
Caused by: org.springframework.boot.web.server.WebServerException: Unable to start embedded Tomcat
	at org.springframework.boot.web.embedded.tomcat.TomcatWebServer.initialize(TomcatWebServer.java:125) ~[spring-boot-2.1.0.RELEASE.jar:2.1.0.RELEASE]
	at org.springframework.boot.web.embedded.tomcat.TomcatWebServer.<init>(TomcatWebServer.java:86) ~[spring-boot-2.1.0.RELEASE.jar:2.1.0.RELEASE]
	at org.springframework.boot.web.embedded.tomcat.TomcatServletWebServerFactory.getTomcatWebServer(TomcatServletWebServerFactory.java:414) ~[spring-boot-2.1.0.RELEASE.jar:2.1.0.RELEASE]
	at org.springframework.boot.web.embedded.tomcat.TomcatServletWebServerFactory.getWebServer(TomcatServletWebServerFactory.java:174) ~[spring-boot-2.1.0.RELEASE.jar:2.1.0.RELEASE]
	at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.createWebServer(ServletWebServerApplicationContext.java:179) ~[spring-boot-2.1.0.RELEASE.jar:2.1.0.RELEASE]
	at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.onRefresh(ServletWebServerApplicationContext.java:152) ~[spring-boot-2.1.0.RELEASE.jar:2.1.0.RELEASE]
	... 8 common frames omitted
Caused by: java.lang.IllegalStateException: StandardEngine[Tomcat].StandardHost[localhost].TomcatEmbeddedContext[] failed to start
	at org.springframework.boot.web.embedded.tomcat.TomcatWebServer.rethrowDeferredStartupExceptions(TomcatWebServer.java:171) ~[spring-boot-2.1.0.RELEASE.jar:2.1.0.RELEASE]
	at org.springframework.boot.web.embedded.tomcat.TomcatWebServer.initialize(TomcatWebServer.java:109) ~[spring-boot-2.1.0.RELEASE.jar:2.1.0.RELEASE]
	... 13 common frames omitted

我用的 springboot 版本是：2.1.0.RELEASE ； springcloud 版本是：Greenwich.RELEASE
jdk是12。
在网上找了很久都不行，试着换了springboot和springcloud版本，springboot 用 2.3.1.RELEASE；springcloud 用 Hoxton.SR1，结果就成了

所以我认为是springboot和springcloud版本对不上造成了，我是照着视频搬的版本号，视频里可以，我却运行不了，这到底是什么原因，希望遇到同样问题并解决的小伙伴留言点醒我，谢谢！