Caused by: java.lang.NullPointerException: null at springfox.documentation.spi.service.contexts.Orderings$8.compare(Orderings.java:113) ~[springfox-spi-2.7.0.jar:2.7.0] at springfox.documentation.spi.service.contexts.Orderings$8.compare(Orderings.java:110) ~[springfox-spi-2.7.0.jar:2.7.0] at com.google.common.collect.ComparatorOrdering.compare(ComparatorOrdering.java:38) ~[guava-18.0.jar:na] at java.util.TimSort.countRunAndMakeAscending(TimSort.java:355) ~[na:1.8.0_271] at java.util.TimSort.sort(TimSort.java:220) ~[na:1.8.0_271] at java.util.Arrays.sort(Arrays.java:1438) ~[na:1.8.0_271] at com.google.common.collect.Ordering.sortedCopy(Ordering.java:817) ~[guava-18.0.jar:na] at springfox.documentation.spring.web.plugins.WebMvcRequestHandlerProvider.requestHandlers(WebMvcRequestHandlerProvider.java:52) ~[springfox-spring-web-2.7.0.jar:2.7.0] at springfox.documentation.spring.web.plugins.DocumentationPluginsBootstrapper$2.apply(DocumentationPluginsBootstrapper.java:129) ~[springfox-spring-web-2.7.0.jar:2.7.0] at springfox.documentation.spring.web.plugins.DocumentationPluginsBootstrapper$2.apply(DocumentationPluginsBootstrapper.java:126) ~[springfox-spring-web-2.7.0.jar:2.7.0] at com.google.common.collect.Iterators$8.transform(Iterators.java:799) ~[guava-18.0.jar:na] at com.google.common.collect.TransformedIterator.next(TransformedIterator.java:48) ~[guava-18.0.jar:na] at com.google.common.collect.TransformedIterator.next(TransformedIterator.java:48) ~[guava-18.0.jar:na] at com.google.common.collect.Iterators$5.hasNext(Iterators.java:548) ~[guava-18.0.jar:na] at com.google.common.collect.ImmutableList.copyOf(ImmutableList.java:268) ~[guava-18.0.jar:na] at com.google.common.collect.ImmutableList.copyOf(ImmutableList.java:226) ~[guava-18.0.jar:na] at com.google.common.collect.FluentIterable.toList(FluentIterable.java:373) ~[guava-18.0.jar:na] at springfox.documentation.spring.web.plugins.DocumentationPluginsBootstrapper.defaultContextBuilder(DocumentationPluginsBootstrapper.java:100) ~[springfox-spring-web-2.7.0.jar:2.7.0] at springfox.documentation.spring.web.plugins.DocumentationPluginsBootstrapper.buildContext(DocumentationPluginsBootstrapper.java:91) ~[springfox-spring-web-2.7.0.jar:2.7.0] at springfox.documentation.spring.web.plugins.DocumentationPluginsBootstrapper.start(DocumentationPluginsBootstrapper.java:154) ~[springfox-spring-web-2.7.0.jar:2.7.0] at org.springframework.context.support.DefaultLifecycleProcessor.doStart(DefaultLifecycleProcessor.java:178) ~[spring-context-5.3.19.jar:5.3.19]
可以看到是swagger2出现了问题。
尝试了在swagger配置类上把@EnableSwagger2注解改为@EnableWebMvc发现修改完是不报错了，但是swagger界面也打不开了
最后解决办法是 在项目配置文件中加入
spring.mvc.pathmatch.matching-strategy=ant-path-matcher
原因：出现以上错误，是由Springfox的一个bug引起的，这是在假设SpringMVC是如何建立的，但这并不总是成立的。具体来说，它假设MVC的路径匹配将使用基于Ant-based的路径匹配器，而不是基于PathPattern-based的匹配器。基于PathPattern-based的匹配已经是一个选项，并且是SpringBoot2.6的默认选项。
参考：https://www.cnblogs.com/huyueping/p/15607970.html
