Spring Boot常见问题（二）Unable to start embedded container; nested exception is java.lang.NoSuchMethodError: org.apache.tomcat.util.scan.StandardJarScanner.setJarScanFilter(Lorg/apache/tomcat/JarScanFilter;
问题描述：通过Spring Boot官方提供的方式，写出如下HelloWorld代码。
@Controller @EnableAutoConfiguration public class HelloWorld { @RequestMapping("/wu") @ResponseBody String home() { return "Hello World!"; } public static void main(String[] args) throws Exception { SpringApplication.run(HelloWorld.class, args); } }
在运行main()方法时，抛出如下异常。
org.springframework.context.ApplicationContextException: Unable to start embedded container; nested exception is java.lang.NoSuchMethodError: org.apache.tomcat.util.scan.StandardJarScanner.setJarScanFilter(Lorg/apache/tomcat/JarScanFilter;)V at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.onRefresh(EmbeddedWebApplicationContext.java:137) ~[spring-boot-1.5.6.RELEASE.jar:1.5.6.RELEASE] at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:537) ~[spring-context-4.3.10.RELEASE.jar:4.3.10.RELEASE] at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:122) ~[spring-boot-1.5.6.RELEASE.jar:1.5.6.RELEASE] at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:693) [spring-boot-1.5.6.RELEASE.jar:1.5.6.RELEASE] at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:360) [spring-boot-1.5.6.RELEASE.jar:1.5.6.RELEASE] at org.springframework.boot.SpringApplication.run(SpringApplication.java:303) [spring-boot-1.5.6.RELEASE.jar:1.5.6.RELEASE] at org.springframework.boot.SpringApplication.run(SpringApplication.java:1118) [spring-boot-1.5.6.RELEASE.jar:1.5.6.RELEASE] at org.springframework.boot.SpringApplication.run(SpringApplication.java:1107) [spring-boot-1.5.6.RELEASE.jar:1.5.6.RELEASE] at dolphin.springboot.controller.HelloWorld.main(HelloWorld.java:30) [classes/:na] Caused by: java.lang.NoSuchMethodError: org.apache.tomcat.util.scan.StandardJarScanner.setJarScanFilter(Lorg/apache/tomcat/JarScanFilter;)V at org.springframework.boot.context.embedded.tomcat.SkipPatternJarScanner$Tomcat8TldSkipSetter.setSkipPattern(SkipPatternJarScanner.java:106) ~[spring-boot-1.5.6.RELEASE.jar:1.5.6.RELEASE] at org.springframework.boot.context.embedded.tomcat.SkipPatternJarScanner.setPatternToTomcat8SkipFilter(SkipPatternJarScanner.java:61) ~[spring-boot-1.5.6.RELEASE.jar:1.5.6.RELEASE] at org.springframework.boot.context.embedded.tomcat.SkipPatternJarScanner.<init>(SkipPatternJarScanner.java:56) ~[spring-boot-1.5.6.RELEASE.jar:1.5.6.RELEASE] at org.springframework.boot.context.embedded.tomcat.SkipPatternJarScanner.apply(SkipPatternJarScanner.java:87) ~[spring-boot-1.5.6.RELEASE.jar:1.5.6.RELEASE] at org.springframework.boot.context.embedded.tomcat.TomcatEmbeddedServletContainerFactory.prepareContext(TomcatEmbeddedServletContainerFactory.java:209) ~[spring-boot-1.5.6.RELEASE.jar:1.5.6.RELEASE] at org.springframework.boot.context.embedded.tomcat.TomcatEmbeddedServletContainerFactory.getEmbeddedServletContainer(TomcatEmbeddedServletContainerFactory.java:178) ~[spring-boot-1.5.6.RELEASE.jar:1.5.6.RELEASE] at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.createEmbeddedServletContainer(EmbeddedWebApplicationContext.java:164) ~[spring-boot-1.5.6.RELEASE.jar:1.5.6.RELEASE] at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.onRefresh(EmbeddedWebApplicationContext.java:134) ~[spring-boot-1.5.6.RELEASE.jar:1.5.6.RELEASE] ... 8 common frames omitted
经检查，在org.apache.tomcat.util.scan.StandardJarScanner类中存在setJarScanFilter(Lorg/apache/tomcat/JarScanFilter;)方法，并且亲自测试，可以正常使用。而抛出异常却说没有此方法。
分析原因：1.存在重复的jar包。2.版本调整带来的影响。
经排查，发现MyEclipse Tomcat v7.0 Runtime Libraries包，和Maven Dependencies包中均包含org.apache.tomcat.util.scan.StandardJarScanner类。
于是，取消MyEclipse Tomcat v7.0 Runtime Libraries包，运行正常。
. ____ _ __ _ _ /\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \ ( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \ \\/ ___)| |_)| | | | | || (_| | ) ) ) ) ' |____| .__|_| |_|_| |_\__, | / / / / =========|_|==============|___/=/_/_/_/ :: Spring Boot :: (v1.5.6.RELEASE) 2017-09-09 09:27:03.646 INFO 6400 --- [ main] d.springboot.controller.HelloWorld : Starting HelloWorld on DESKTOP-N8HPR69 with PID 6400 (started by wushuai in C:\Users\wushuai\Workspaces\MyEclipse for Spring 2014\springboot Maven Webapp) 2017-09-09 09:27:03.648 INFO 6400 --- [ main] d.springboot.controller.HelloWorld : No active profile set, falling back to default profiles: default 2017-09-09 09:27:03.679 INFO 6400 --- [ main] ationConfigEmbeddedWebApplicationContext : Refreshing org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@5680a576: startup date [Sat Sep 09 09:27:03 CST 2017]; root of context hierarchy 2017-09-09 09:27:04.734 INFO 6400 --- [ main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat initialized with port(s): 8080 (http) 2017-09-09 09:27:04.743 INFO 6400 --- [ main] o.apache.catalina.core.StandardService : Starting service [Tomcat] 2017-09-09 09:27:04.744 INFO 6400 --- [ main] org.apache.catalina.core.StandardEngine : Starting Servlet Engine: Apache Tomcat/8.5.16 2017-09-09 09:27:04.820 INFO 6400 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring embedded WebApplicationContext 2017-09-09 09:27:04.820 INFO 6400 --- [ost-startStop-1] o.s.web.context.ContextLoader : Root WebApplicationContext: initialization completed in 1143 ms 2017-09-09 09:27:04.952 INFO 6400 --- [ost-startStop-1] o.s.b.w.servlet.ServletRegistrationBean : Mapping servlet: 'dispatcherServlet' to [/] 2017-09-09 09:27:04.956 INFO 6400 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'characterEncodingFilter' to: [/*] 2017-09-09 09:27:04.956 INFO 6400 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'hiddenHttpMethodFilter' to: [/*] 2017-09-09 09:27:04.956 INFO 6400 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'httpPutFormContentFilter' to: [/*] 2017-09-09 09:27:04.956 INFO 6400 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'requestContextFilter' to: [/*] 2017-09-09 09:27:05.266 INFO 6400 --- [ main] s.w.s.m.m.a.RequestMappingHandlerAdapter : Looking for @ControllerAdvice: org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@5680a576: startup date [Sat Sep 09 09:27:03 CST 2017]; root of context hierarchy 2017-09-09 09:27:05.324 INFO 6400 --- [ main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/wu]}" onto java.lang.String dolphin.springboot.controller.HelloWorld.home() 2017-09-09 09:27:05.327 INFO 6400 --- [ main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error]}" onto public org.springframework.http.ResponseEntity<java.util.Map<java.lang.String, java.lang.Object>> org.springframework.boot.autoconfigure.web.BasicErrorController.error(javax.servlet.http.HttpServletRequest) 2017-09-09 09:27:05.328 INFO 6400 --- [ main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error],produces=[text/html]}" onto public org.springframework.web.servlet.ModelAndView org.springframework.boot.autoconfigure.web.BasicErrorController.errorHtml(javax.servlet.http.HttpServletRequest,javax.servlet.http.HttpServletResponse) 2017-09-09 09:27:05.356 INFO 6400 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/webjars/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler] 2017-09-09 09:27:05.356 INFO 6400 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler] 2017-09-09 09:27:05.398 INFO 6400 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/**/favicon.ico] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler] 2017-09-09 09:27:05.580 INFO 6400 --- [ main] o.s.j.e.a.AnnotationMBeanExporter : Registering beans for JMX exposure on startup 2017-09-09 09:27:05.650 INFO 6400 --- [ main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat started on port(s): 8080 (http) 2017-09-09 09:27:05.655 INFO 6400 --- [ main] d.springboot.controller.HelloWorld : Started HelloWorld in 2.298 seconds (JVM running for 2.534)
解决办法：查看报错文件所在的包，移除重复部分。
