一、报错信息 
        org.springframework.context.ApplicationContextException: Failed to start bean 'documentationPluginsBootstrapper'; nested exception is java.lang.NullPointerException

具体报错信息如下：

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:740)
	at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:415)
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:303)
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1312)
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1301)
	at com.www.wen.Application.main(Application.java:13)
Caused by: java.lang.NullPointerException: null
	at springfox.documentation.spring.web.WebMvcPatternsRequestConditionWrapper.getPatterns(WebMvcPatternsRequestConditionWrapper.java:56)
	at springfox.documentation.RequestHandler.sortedPaths(RequestHandler.java:113)
	at springfox.documentation.spi.service.contexts.Orderings.lambda$byPatternsCondition$3(Orderings.java:89)
	at java.util.Comparator.lambda$comparing$77a9974f$1(Comparator.java:469)
	at java.util.TimSort.countRunAndMakeAscending(TimSort.java:355)
	at java.util.TimSort.sort(TimSort.java:234)
	at java.util.Arrays.sort(Arrays.java:1512)
	at java.util.ArrayList.sort(ArrayList.java:1462)
	at java.util.stream.SortedOps$RefSortingSink.end(SortedOps.java:387)
	at java.util.stream.Sink$ChainedReference.end(Sink.java:258)
	at java.util.stream.Sink$ChainedReference.end(Sink.java:258)
	at java.util.stream.Sink$ChainedReference.end(Sink.java:258)
	at java.util.stream.Sink$ChainedReference.end(Sink.java:258)
	at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:483)
	at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:472)
	at java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:708)
	at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
	at java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:499)
	at springfox.documentation.spring.web.plugins.WebMvcRequestHandlerProvider.requestHandlers(WebMvcRequestHandlerProvider.java:81)
	at java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:193)
	at java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1382)
	at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:482)
	at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:472)
	at java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:708)
	at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
	at java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:499)
	at springfox.documentation.spring.web.plugins.AbstractDocumentationPluginsBootstrapper.withDefaults(AbstractDocumentationPluginsBootstrapper.java:107)
	at springfox.documentation.spring.web.plugins.AbstractDocumentationPluginsBootstrapper.buildContext(AbstractDocumentationPluginsBootstrapper.java:91)
	at springfox.documentation.spring.web.plugins.AbstractDocumentationPluginsBootstrapper.bootstrapDocumentationPlugins(AbstractDocumentationPluginsBootstrapper.java:82)
	at springfox.documentation.spring.web.plugins.DocumentationPluginsBootstrapper.start(DocumentationPluginsBootstrapper.java:100)
	at org.springframework.context.support.DefaultLifecycleProcessor.doStart(DefaultLifecycleProcessor.java:178)
	... 14 common frames omitted

二、报错原因

        SpringBoot2.6.x与Swagger2 3.0.0版本冲突原因。

三、解决方案

方案一：

        将SpringBoot版本降低到2.6以下。

方案二：

• 在application.yml中添加以下配置：

• spring:
    mvc:
     pathmatch:
       matching-strategy: ant_path_matcher

 Swagger配置类
        如上，更改SpringMVC处理程序映射匹配请求路径策略为ant_path_matcher不起作用，可以Spring容器中注册一个BeanPostProcessor，在postProcessAfterInitialization中修改WebMvcRequestHandlerProvider中的handlerMappings属性。

@Configuration
@EnableOpenApi
@Slf4j
public class SwaggerConfig implements ApplicationListener<WebServerInitializedEvent> {
    @Bean
    public Docket createRestApi(){
        return new Docket(DocumentationType.SWAGGER_2)
                .apiInfo(getApiInfo())
                .pathMapping("/")
                .select()
                .apis(RequestHandlerSelectors.basePackage("com.www.wen")) 
                .paths(PathSelectors.any())
                .build();
    }
 
    public ApiInfo getApiInfo(){
        return new ApiInfoBuilder()
                .title("xxx应用平台") // 文档标题
                .description("xxx应用平台文档描述") // 文档描述
                .termsOfServiceUrl("http://www.baidu.com")
                .version("1.0")
                .build();
 
    }
    
    /**
     * 解决SpringBoot和Swagger2冲突
     *
     * @return
     */
    @Bean
    public static BeanPostProcessor springfoxHandlerProviderBeanPostProcessor() {
        return new BeanPostProcessor() {
 
            @Override
            public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
                if (bean instanceof WebMvcRequestHandlerProvider || bean instanceof WebFluxRequestHandlerProvider) {
                    customizeSpringfoxHandlerMappings(getHandlerMappings(bean));
                }
                return bean;
            }
 
            private <T extends RequestMappingInfoHandlerMapping> void customizeSpringfoxHandlerMappings(List<T> mappings) {
                List<T> copy = mappings.stream()
                        .filter(mapping -> mapping.getPatternParser() == null)
                        .collect(Collectors.toList());
                mappings.clear();
                mappings.addAll(copy);
            }
 
            @SuppressWarnings("unchecked")
            private List<RequestMappingInfoHandlerMapping> getHandlerMappings(Object bean) {
                try {
                    Field field = ReflectionUtils.findField(bean.getClass(), "handlerMappings");
                    field.setAccessible(true);
                    return (List<RequestMappingInfoHandlerMapping>) field.get(bean);
                } catch (IllegalArgumentException | IllegalAccessException e) {
                    log.warn("修改WebMvcRequestHandlerProvider的属性：handlerMappings出错，可能导致swagger不可用", e);
                    throw new IllegalStateException(e);
                }
            }
        };
    }
}