springboot及swagger2整合报错：documentationPluginsBootstrapper

我不是女神ヾ 2024-05-25 17:36 112阅读 0赞

#### springboot及swagger2整合报错：documentationPluginsBootstrapper ####

*  1. 先给出解决方案
 *  2.高版本整合出错及详细解决方案

## 1. 先给出解决方案 ##

如果英文好直接参考这篇文章：[https://fullstackcode.dev/2022/06/12/swagger-is-not-working-with-spring-boot-2-6-x/][https_fullstackcode.dev_2022_06_12_swagger-is-not-working-with-spring-boot-2-6-x]，这是我尝试了网上多种解决方案无果之后，真正解决了问题的文章，当然作者参考的也是官方讨论组，详情过程可以查看：[https://github.com/springfox/springfox/issues/3462][https_github.com_springfox_springfox_issues_3462]。这里面也告诉我们一般出现插件问题，记得第一时间去查看开源项目里面的issues，一般你遇到的问题，大家都会遇到，尤其国外程序员一般都乐意分享，大多数时候都能找到答案。

我使用的是作者给到的第三种方案：

1.  添加actuator依赖：

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

1.  修改Application.yml配置：

mvc:
        pathmatch:
          matching-strategy: ANT_PATH_MATCHER

如果是properties文件，配置如下：

spring.mvc.pathmatch.matching-strategy=ant_path_matcher

swagger配置文件添加关键方法：

@Configuration
    @EnableSwagger2
    public class SwaggerConfig {
        
        @Bean
        public Docket api() {
        
            return new Docket(DocumentationType.SWAGGER_2)
                    .select()
                    .apis(RequestHandlerSelectors.any())
                    .paths(PathSelectors.any())
                    .build();
        }
    
        @Bean
        public WebMvcEndpointHandlerMapping webEndpointServletHandlerMapping(WebEndpointsSupplier webEndpointsSupplier, ServletEndpointsSupplier servletEndpointsSupplier, ControllerEndpointsSupplier controllerEndpointsSupplier, EndpointMediaTypes endpointMediaTypes, CorsEndpointProperties corsProperties, WebEndpointProperties webEndpointProperties, Environment environment) {
        
            List<ExposableEndpoint<?>> allEndpoints = new ArrayList();
            Collection<ExposableWebEndpoint> webEndpoints = webEndpointsSupplier.getEndpoints();
            allEndpoints.addAll(webEndpoints);
            allEndpoints.addAll(servletEndpointsSupplier.getEndpoints());
            allEndpoints.addAll(controllerEndpointsSupplier.getEndpoints());
            String basePath = webEndpointProperties.getBasePath();
            EndpointMapping endpointMapping = new EndpointMapping(basePath);
            boolean shouldRegisterLinksMapping = this.shouldRegisterLinksMapping(webEndpointProperties, environment, basePath);
            return new WebMvcEndpointHandlerMapping(endpointMapping, webEndpoints, endpointMediaTypes, corsProperties.toCorsConfiguration(), new EndpointLinksResolver(allEndpoints, basePath), shouldRegisterLinksMapping, null);
        }
    
        private boolean shouldRegisterLinksMapping(WebEndpointProperties webEndpointProperties, Environment environment, String basePath) {
        
            return webEndpointProperties.getDiscovery().isEnabled() && (StringUtils.hasText(basePath) || ManagementPortType.get(environment).equals(ManagementPortType.DIFFERENT));
        }
    }

从代码来看，里面的核心方法webEndpointServletHandlerMapping，做了高版本的兼容，我估计在后面Swagger如果做更新的时候，应该会做一定的兼容性。

## 2.高版本整合出错及详细解决方案 ##

以前使用Swagger版本的时候，都是一次性启动成功，但是这次将Springboot使用新版本之后，居然报错了，主要的错误信息如下：

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) ~[spring-context-5.3.23.jar:5.3.23]
    	at org.springframework.context.support.DefaultLifecycleProcessor.access$200(DefaultLifecycleProcessor.java:54) ~[spring-context-5.3.23.jar:5.3.23]
    	at org.springframework.context.support.DefaultLifecycleProcessor$LifecycleGroup.start(DefaultLifecycleProcessor.java:356) ~[spring-context-5.3.23.jar:5.3.23]
    	at java.base/java.lang.Iterable.forEach(Iterable.java:75) ~[na:na]
    	at org.springframework.context.support.DefaultLifecycleProcessor.startBeans(DefaultLifecycleProcessor.java:155) ~[spring-context-5.3.23.jar:5.3.23]
    	at org.springframework.context.support.DefaultLifecycleProcessor.onRefresh(DefaultLifecycleProcessor.java:123) ~[spring-context-5.3.23.jar:5.3.23]
    	at org.springframework.context.support.AbstractApplicationContext.finishRefresh(AbstractApplicationContext.java:935) ~[spring-context-5.3.23.jar:5.3.23]
    	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:586) ~[spring-context-5.3.23.jar:5.3.23]
    	at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:147) ~[spring-boot-2.7.4.jar:2.7.4]
    	at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:734) ~[spring-boot-2.7.4.jar:2.7.4]
    	at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:408) ~[spring-boot-2.7.4.jar:2.7.4]
    	at org.springframework.boot.SpringApplication.run(SpringApplication.java:308) ~[spring-boot-2.7.4.jar:2.7.4]
    	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1306) ~[spring-boot-2.7.4.jar:2.7.4]
    	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1295) ~[spring-boot-2.7.4.jar:2.7.4]
    	at stu.up2uper.springstu.SpringStuApplication.main(SpringStuApplication.java:14) ~[classes/:na]
    Caused by: java.lang.NullPointerException: null
    	at springfox.documentation.spi.service.contexts.Orderings$8.compare(Orderings.java:112) ~[springfox-spi-2.9.2.jar:null]
    	at springfox.documentation.spi.service.contexts.Orderings$8.compare(Orderings.java:109) ~[springfox-spi-2.9.2.jar:null]
    	at com.google.common.collect.ComparatorOrdering.compare(ComparatorOrdering.java:37) ~[guava-20.0.jar:na]
    	at java.base/java.util.TimSort.countRunAndMakeAscending(TimSort.java:355) ~[na:na]
    	at java.base/java.util.TimSort.sort(TimSort.java:220) ~[na:na]
    	at java.base/java.util.Arrays.sort(Arrays.java:1232) ~[na:na]
    	at com.google.common.collect.Ordering.sortedCopy(Ordering.java:855) ~[guava-20.0.jar:na]
    	at springfox.documentation.spring.web.plugins.WebMvcRequestHandlerProvider.requestHandlers(WebMvcRequestHandlerProvider.java:57) ~[springfox-spring-web-2.9.2.jar:null]
    	at springfox.documentation.spring.web.plugins.DocumentationPluginsBootstrapper$2.apply(DocumentationPluginsBootstrapper.java:138) ~[springfox-spring-web-2.9.2.jar:null]
    	at springfox.documentation.spring.web.plugins.DocumentationPluginsBootstrapper$2.apply(DocumentationPluginsBootstrapper.java:135) ~[springfox-spring-web-2.9.2.jar:null]
    	at com.google.common.collect.Iterators$7.transform(Iterators.java:750) ~[guava-20.0.jar:na]
    	at com.google.common.collect.TransformedIterator.next(TransformedIterator.java:47) ~[guava-20.0.jar:na]
    	at com.google.common.collect.TransformedIterator.next(TransformedIterator.java:47) ~[guava-20.0.jar:na]
    	at com.google.common.collect.MultitransformedIterator.hasNext(MultitransformedIterator.java:52) ~[guava-20.0.jar:na]
    	at com.google.common.collect.MultitransformedIterator.hasNext(MultitransformedIterator.java:50) ~[guava-20.0.jar:na]
    	at com.google.common.collect.ImmutableList.copyOf(ImmutableList.java:249) ~[guava-20.0.jar:na]
    	at com.google.common.collect.ImmutableList.copyOf(ImmutableList.java:209) ~[guava-20.0.jar:na]
    	at com.google.common.collect.FluentIterable.toList(FluentIterable.java:614) ~[guava-20.0.jar:na]
    	at springfox.documentation.spring.web.plugins.DocumentationPluginsBootstrapper.defaultContextBuilder(DocumentationPluginsBootstrapper.java:111) ~[springfox-spring-web-2.9.2.jar:null]
    	at springfox.documentation.spring.web.plugins.DocumentationPluginsBootstrapper.buildContext(DocumentationPluginsBootstrapper.java:96) ~[springfox-spring-web-2.9.2.jar:null]
    	at springfox.documentation.spring.web.plugins.DocumentationPluginsBootstrapper.start(DocumentationPluginsBootstrapper.java:167) ~[springfox-spring-web-2.9.2.jar:null]
    	at org.springframework.context.support.DefaultLifecycleProcessor.doStart(DefaultLifecycleProcessor.java:178) ~[spring-context-5.3.23.jar:5.3.23]
    	... 14 common frames omitted

我引用的相关包信息如下：

<parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.7.4</version>
        <relativePath/> 
    </parent>
    <dependencies>
    	<dependency>
          <groupId>io.springfox</groupId>
           <artifactId>springfox-swagger2</artifactId>
           <version>2.9.2</version>
       </dependency>
       <dependency>
           <groupId>io.springfox</groupId>
           <artifactId>springfox-swagger-ui</artifactId>
           <version>2.9.2</version>
       </dependency>
    </dependencies>

第一反应就是版本冲突不兼容导致的，百度了几种方案都无果，主要一下几种方案：

*  版本兼容法：降低springboot版本，使用配套swagger
 *  更新Google Guava法：升级或者指定特定guava版本
 *  修改注释法：添加@EnableWebMvc之类的注解之类来修改

@EnableAsync
    @EnableWebMvc
    @ServletComponentScan
    @ComponentScan(basePackages = {
        "com.xmair.restapi","com.xmair.core.service"})
    @MapperScan("com.xmair.core.mapper")
    public class MFISRestAPIApplication {
        
        public static void main(String[] args) {
        
            ConfigurableApplicationContext context = SpringApplication.run(MFISRestAPIApplication.class, args);
        }
    }

*  添加资源法：估计是无法获取swagger所需资源，而导致无法启动

@Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        
            registry.addResourceHandler("/**").addResourceLocations("classpath:/static/");
            registry.addResourceHandler("doc.html").addResourceLocations("classpath:/META-INF/resources/");
            registry.addResourceHandler("/webjars/**").addResourceLocations("classpath:/META-INF/resources/webjars/");
            registry.addResourceHandler("swagger-ui.html").addResourceLocations("classpath:/META-INF/resources/");
    }

反正以上方案都没解决我的问题，可能上面方法在某些环境及版本之下是适用的，最终还是前面提到的方案解决了问题。方案三已在上方表述，下方把另外两种方案搬砖过来，给大家做参考：

方案一、修改配置及添加兼容代码  
修改配置就是上面一样：

mvc:
        pathmatch:
          matching-strategy: ANT_PATH_MATCHER

如果是properties文件，配置如下：

spring.mvc.pathmatch.matching-strategy=ant_path_matcher

同时，修改核心代码：

@Configuration
    @EnableSwagger2
    public class SwaggerConfig {
        
        
        @Bean
        public Docket api() {
        
            return new Docket(DocumentationType.SWAGGER_2)
                    .select()
                    .apis(RequestHandlerSelectors.any())
                    .paths(PathSelectors.any())
                    .build();
        }
    
        @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) {
        
                        throw new IllegalStateException(e);
                    }
                }
            };
        }
    
    }

方案二、修改swagger配置核心代码

@Configuration
    @EnableSwagger2
    public class SwaggerConfig {
        
    
        @Bean
        public Docket api() {
        
            return new Docket(DocumentationType.SWAGGER_2)
                    .select()
                    .apis(RequestHandlerSelectors.any())
                    .paths(PathSelectors.any())
                    .build();
        }
    
        @Bean
        public InitializingBean removeSpringfoxHandlerProvider(DocumentationPluginsBootstrapper bootstrapper) {
        
            return () -> bootstrapper.getHandlerProviders().removeIf(WebMvcRequestHandlerProvider.class::isInstance);
        }
    
        @Bean
        public RequestHandlerProvider customRequestHandlerProvider(Optional<ServletContext> servletContext, HandlerMethodResolver methodResolver, List<RequestMappingInfoHandlerMapping> handlerMappings) {
        
            String contextPath = servletContext.map(ServletContext::getContextPath).orElse(Paths.ROOT);
            return () -> handlerMappings.stream()
                    .filter(mapping -> !mapping.getClass().getSimpleName().equals("IntegrationRequestMappingHandlerMapping"))
                    .map(mapping -> mapping.getHandlerMethods().entrySet())
                    .flatMap(Set::stream)
                    .map(entry -> new WebMvcRequestHandler(contextPath, methodResolver, tweakInfo(entry.getKey()), entry.getValue()))
                    .sorted(byPatternsCondition())
                    .collect(toList());
        }
    
        RequestMappingInfo tweakInfo(RequestMappingInfo info) {
        
            if (info.getPathPatternsCondition() == null) return info;
            String[] patterns = info.getPathPatternsCondition().getPatternValues().toArray(String[]::new);
            return info.mutate().options(new RequestMappingInfo.BuilderConfiguration()).paths(patterns).build();
        }
    }

希望以上的方案能够帮助大家解决问题，同时通过这次解决问题，又一次验证了遇到开源项目错误的解决途径：

**简单百度无果，一定要用Google，或者开源项目的讨论区。**

[https_fullstackcode.dev_2022_06_12_swagger-is-not-working-with-spring-boot-2-6-x]: https://fullstackcode.dev/2022/06/12/swagger-is-not-working-with-spring-boot-2-6-x/
[https_github.com_springfox_springfox_issues_3462]: https://github.com/springfox/springfox/issues/3462