SpringBoot 2.7.x 整合 swagger2 冲突问题

问题描述

SpringBoot2.7.x 版本在整合 swagger2 时抛出异常如下：

org.springframework.context.ApplicationContextException: Failed to start bean 'documentationPluginsBootstrapper'; nested exception is java.lang.NullPointerException
	at org.springframework.context.support.DefaultLifecycleProcessor.doStart(DefaultLifecycleProcessor.java:181)
	at org.springframework.context.support.DefaultLifecycleProcessor.access$200(DefaultLifecycleProcessor.java:54)
	at org.springframework.context.support.DefaultLifecycleProcessor$LifecycleGroup.start(DefaultLifecycleProcessor.java:356)
	at java.lang.Iterable.forEach(Iterable.java:75)
	at org.springframework.context.support.DefaultLifecycleProcessor.startBeans(DefaultLifecycleProcessor.java:155)
	at org.springframework.context.support.DefaultLifecycleProcessor.onRefresh(DefaultLifecycleProcessor.java:123)
	at org.springframework.context.support.AbstractApplicationContext.finishRefresh(AbstractApplicationContext.java:935)
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:586)
	at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:145)
	at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:732)
	at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:414)
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:302)
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1303)
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1292)
	at org.xxx.xxx.XXXApplication.main(XXXApplication.java:36)
Caused by: java.lang.NullPointerException: null
	at springfox.documentation.spi.service.contexts.Orderings$8.compare(Orderings.java:112)
	at springfox.documentation.spi.service.contexts.Orderings$8.compare(Orderings.java:109)
	at com.google.common.collect.ComparatorOrdering.compare(ComparatorOrdering.java:37)
	at java.util.TimSort.countRunAndMakeAscending(TimSort.java:355)
	at java.util.TimSort.sort(TimSort.java:234)
	at java.util.Arrays.sort(Arrays.java:1438)
	at com.google.common.collect.Ordering.sortedCopy(Ordering.java:852)
	at springfox.documentation.spring.web.plugins.WebMvcRequestHandlerProvider.requestHandlers(WebMvcRequestHandlerProvider.java:57)
	at springfox.documentation.spring.web.plugins.DocumentationPluginsBootstrapper$2.apply(DocumentationPluginsBootstrapper.java:138)
	at springfox.documentation.spring.web.plugins.DocumentationPluginsBootstrapper$2.apply(DocumentationPluginsBootstrapper.java:135)
	at com.google.common.collect.Iterators$6.transform(Iterators.java:788)
	at com.google.common.collect.TransformedIterator.next(TransformedIterator.java:47)
	at com.google.common.collect.TransformedIterator.next(TransformedIterator.java:47)
	at com.google.common.collect.Iterators$ConcatenatedIterator.hasNext(Iterators.java:1340)
	at com.google.common.collect.ImmutableList.copyOf(ImmutableList.java:270)
	at com.google.common.collect.ImmutableList.copyOf(ImmutableList.java:234)
	at com.google.common.collect.FluentIterable.toList(FluentIterable.java:617)
	at springfox.documentation.spring.web.plugins.DocumentationPluginsBootstrapper.defaultContextBuilder(DocumentationPluginsBootstrapper.java:111)
	at springfox.documentation.spring.web.plugins.DocumentationPluginsBootstrapper.buildContext(DocumentationPluginsBootstrapper.java:96)
	at springfox.documentation.spring.web.plugins.DocumentationPluginsBootstrapper.start(DocumentationPluginsBootstrapper.java:167)
	at org.springframework.context.support.DefaultLifecycleProcessor.doStart(DefaultLifecycleProcessor.java:178)
	... 14 common frames omitted

原因分析

swagger2 与 SpringBoot2.7.x 版本冲突，根本原因是 SpringBoot2.7.x mvc 模块默认路径路由模式 与 swagger2 不同，导致出现不一致。

解决办法

手动配置 mvc 路由映射模式，修改 application.properties 文件如下：

#解决 swagger2 不兼容 springboot2.7.x版本问题
spring.mvc.pathmatch.matching-strategy=ant_path_matcher

但是，再次启动 SpringBoot，结果问题却依然存在 ：（

看来 SpringBoot2.7.x 与 Swagger2 版本冲突问题并未完全解决。

查看网上所有博客，没有发现任何解决办法，只能采用排除法，一个个依赖进行排除。

最终，终于发现问题所在，原来是 spring-boot-start-actuator 监控模块与 Swaggger2 产生冲突。
注释 spring-boot-start-actuator 模块依赖，如下：

        <!-- actuator 功能 -->
<!--        <dependency>-->
<!--            <groupId>org.springframework.boot</groupId>-->
<!--            <artifactId>spring-boot-starter-actuator</artifactId>-->
<!--        </dependency>-->

再次运行 SpringBoot，显示 OK：）