在spring boot启动时，报如下错误
[org.apache.catalina.core.ContainerBase::log(181)] ：A child container failed during start java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Tomcat].StandardHost[localhost].TomcatEmbeddedContext[/middleware]]
at java.util.concurrent.FutureTask.report(FutureTask.java:122) ~[?:1.8.0_144]
at java.util.concurrent.FutureTask.get(FutureTask.java:192) ~[?:1.8.0_144]
at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:939) [tomcat-embed-core-8.5.11.jar:8.5.11]
at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:872) [tomcat-embed-core-8.5.11.jar:8.5.11]
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150) [tomcat-embed-core-8.5.11.jar:8.5.11]
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1419) [tomcat-embed-core-8.5.11.jar:8.5.11]
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1409) [tomcat-embed-core-8.5.11.jar:8.5.11]
at java.util.concurrent.FutureTask.run(FutureTask.java:266) [?:1.8.0_144]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [?:1.8.0_144]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [?:1.8.0_144]
这个原因是在pom.xml文件中配置了servlet-api的包配置，与spring boot本身自带的冲突，导致报这错。解决办法就是把servlet-api在pom.xml文件中删除。