Swagger Failed to start bean ‘documentationPluginsBootstrapper‘；XXX java.lang.NullPointerException

拼搏现实的明天。 2024-03-25 22:31 31阅读 0赞

#### 一、问题现象 ####

当 Spring Boot 2.6.x 和 Swagger 3.0.0 整合的时候，工程启动报错。  
重点报错信息：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:147)
        at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:734)
        at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:408)
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:308)
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:1306)
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:1295)
        at com.ktr.htmcs.HtmcsApplication.main(HtmcsApplication.java:15)
    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:482)
        at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:471)
        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:481)
        at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:471)
        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
    2023-01-06 14:02:57.699 [Thread-6] WARN  com.alibaba.nacos.common.http.HttpClientBeanHolder:108 - [HttpClientBeanHolder] Start destroying common HttpClient
    2023-01-06 14:02:57.699 [Thread-48] WARN  com.alibaba.nacos.common.notify.NotifyCenter:145 - [NotifyCenter] Start destroying Publisher
    2023-01-06 14:02:57.699 [Thread-6] WARN  com.alibaba.nacos.common.http.HttpClientBeanHolder:114 - [HttpClientBeanHolder] Destruction of the end
    2023-01-06 14:02:57.699 [Thread-48] WARN  com.alibaba.nacos.common.notify.NotifyCenter:162 - [NotifyCenter] Destruction of the end

#### 二、问题原因 ####

因为 **Springfox** 使用的路径匹配是基于**AntPathMatcher** 的，而 **Spring Boot 2.6.X** 使用的是 **PathPatternMatcher**。

#### 三、解决方案 ####

##### 1、配置文件中添加配置 #####

**application.yml** 或 **applicaiton.properties** 中添加如下配置：

spring:
      mvc:
        pathmatch:
          matching-strategy: ant_path_matcher

##### 2、新建 SpringFoxSwaggerConfig.java #####

可以创建一个 **swagger** 目录，然后新建 **SpringFoxSwaggerConfig.java** 文件，内容如下：

import org.springframework.boot.actuate.autoconfigure.endpoint.web.CorsEndpointProperties;
    import org.springframework.boot.actuate.autoconfigure.endpoint.web.WebEndpointProperties;
    import org.springframework.boot.actuate.autoconfigure.web.server.ManagementPortType;
    import org.springframework.boot.actuate.endpoint.ExposableEndpoint;
    import org.springframework.boot.actuate.endpoint.web.*;
    import org.springframework.boot.actuate.endpoint.web.annotation.ControllerEndpointsSupplier;
    import org.springframework.boot.actuate.endpoint.web.annotation.ServletEndpointsSupplier;
    import org.springframework.boot.actuate.endpoint.web.servlet.WebMvcEndpointHandlerMapping;
    import org.springframework.context.annotation.Bean;
    import org.springframework.context.annotation.Configuration;
    import org.springframework.core.env.Environment;
    import org.springframework.util.StringUtils;
    import org.springframework.web.bind.annotation.RestController;
    import springfox.documentation.builders.ApiInfoBuilder;
    import springfox.documentation.builders.PathSelectors;
    import springfox.documentation.builders.RequestHandlerSelectors;
    import springfox.documentation.oas.annotations.EnableOpenApi;
    import springfox.documentation.service.ApiInfo;
    import springfox.documentation.service.Contact;
    import springfox.documentation.spi.DocumentationType;
    import springfox.documentation.spring.web.plugins.Docket;
    
    import java.util.ArrayList;
    import java.util.Collection;
    import java.util.List;
    
    /***
     * @author Miracle Luna
     * @date 2023/1/6
     * @apiNote
     */
    @EnableOpenApi
    @Configuration
    public class SpringFoxSwaggerConfig {
        
        /**
         * 配置基本信息
         * @return
         */
        @Bean
        public ApiInfo apiInfo() {
        
            return new ApiInfoBuilder()
                    .title("Swagger API文档")
                    .description("Swagger API文档")
                    .contact(new Contact("Miracle Luna","",""))
                    .version("1.0")
                    .build();
        }
    
        /**
         * 配置文档生成最佳实践
         * @param apiInfo
         * @return
         */
        @Bean
        public Docket createRestApi(ApiInfo apiInfo) {
        
            return new Docket(DocumentationType.OAS_30)
                    .apiInfo(apiInfo)
                    .groupName("SwaggerGroupOneAPI")
                    .select()
                    .apis(RequestHandlerSelectors.withClassAnnotation(RestController.class))
                    .paths(PathSelectors.any())
                    .build();
        }
    
        /**
         * 增加如下配置可解决Spring Boot 2.6.x 与Swagger 3.0.0 不兼容问题
         **/
        @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));
        }
    }

之后，再重启 SpringBoot 工程，即可正常启动。