SpringBoot整合Swagger3.0使用及报错解决大全

前言

Swagger是一个规范和完整的框架，用于生成、描述、调用和可视化 RESTful 风格的 Web服务。总体目标是使客户端和文件系统作为服务器以同样的速度来更新。文件的方法，参数和模型紧密集成到服务器端的代码，允许API来始终保持同步。

Step	Description
1	引入Maven依赖
2	在Spring Boot中启用Swagger
3	创建SwaggerConfig类
4	创建Docket Bean
5	提供API信息
6	配置Swagger UI
7	应用Swagger

项目背景

版本

SpringBoot 2.7.*
springfox 3.0

Maven依赖

<!-- Swagger -->
<dependency>
    <groupId>io.springfox</groupId>
    <artifactId>springfox-swagger2</artifactId>
    <version>3.0.0</version>
</dependency>
<!-- 或-->
<dependency>
	<groupId>io.springfox</groupId>
	<artifactId>springfox-boot-starter</artifactId>
	<version>3.0.0</version>
</dependency>

@Configuration
@EnableSwagger2
@EnableAutoConfiguration
@ConditionalOnProperty(name = "swagger.enabled", matchIfMissing = true)
public class SwaggerAutoConfiguration
{
    /**
     * 默认的排除路径，排除Spring Boot默认的错误处理路径和端点
     */
    private static final List<String> DEFAULT_EXCLUDE_PATH = Arrays.asList("/error", "/actuator/**");

    private static final String BASE_PATH = "/**";

    @Bean
    @ConditionalOnMissingBean
    public SwaggerProperties swaggerProperties()
    {
        return new SwaggerProperties();
    }

    @Bean
    public Docket api(SwaggerProperties swaggerProperties)
    {
        // base-path处理
        if (swaggerProperties.getBasePath().isEmpty())
        {
            swaggerProperties.getBasePath().add(BASE_PATH);
        }
        // noinspection unchecked
        List<Predicate<String>> basePath = new ArrayList<Predicate<String>>();
        swaggerProperties.getBasePath().forEach(path -> basePath.add(PathSelectors.ant(path)));

        // exclude-path处理
        if (swaggerProperties.getExcludePath().isEmpty())
        {
            swaggerProperties.getExcludePath().addAll(DEFAULT_EXCLUDE_PATH);
        }

        List<Predicate<String>> excludePath = new ArrayList<>();
        swaggerProperties.getExcludePath().forEach(path -> excludePath.add(PathSelectors.ant(path)));

        ApiSelectorBuilder builder = new Docket(DocumentationType.SWAGGER_2).host(swaggerProperties.getHost())
                .apiInfo(apiInfo(swaggerProperties)).select()
                .apis(RequestHandlerSelectors.basePackage(swaggerProperties.getBasePackage()));

        swaggerProperties.getBasePath().forEach(p -> builder.paths(PathSelectors.ant(p)));
        swaggerProperties.getExcludePath().forEach(p -> builder.paths(PathSelectors.ant(p).negate()));

        return builder.build().securitySchemes(securitySchemes()).securityContexts(securityContexts()).pathMapping("/");
    }

    /**
     * 安全模式，这里指定token通过Authorization头请求头传递
     */
    private List<SecurityScheme> securitySchemes()
    {
        List<SecurityScheme> apiKeyList = new ArrayList<SecurityScheme>();
        apiKeyList.add(new ApiKey("Authorization", "Authorization", "header"));
        return apiKeyList;
    }

    /**
     * 安全上下文
     */
    private List<SecurityContext> securityContexts()
    {
        List<SecurityContext> securityContexts = new ArrayList<>();
        securityContexts.add(
                SecurityContext.builder()
                        .securityReferences(defaultAuth())
                        .operationSelector(o -> o.requestMappingPattern().matches("/.*"))
                        .build());
        return securityContexts;
    }

    /**
     * 默认的全局鉴权策略
     *
     * @return
     */
    private List<SecurityReference> defaultAuth()
    {
        AuthorizationScope authorizationScope = new AuthorizationScope("global", "accessEverything");
        AuthorizationScope[] authorizationScopes = new AuthorizationScope[1];
        authorizationScopes[0] = authorizationScope;
        List<SecurityReference> securityReferences = new ArrayList<>();
        securityReferences.add(new SecurityReference("Authorization", authorizationScopes));
        return securityReferences;
    }

    private ApiInfo apiInfo(SwaggerProperties swaggerProperties)
    {
         return new ApiInfoBuilder()
             .title(swaggerProperties.getTitle())
             .description(swaggerProperties.getDescription())
             .license(swaggerProperties.getLicense())
             .licenseUrl(swaggerProperties.getLicenseUrl())
             .termsOfServiceUrl(swaggerProperties.getTermsOfServiceUrl())
             .contact(new Contact(swaggerProperties.getContact().getName(), swaggerProperties.getContact().getUrl(), swaggerProperties.getContact().getEmail()))
             .version(swaggerProperties.getVersion())
             .build();
    }
}

@Component
@ConfigurationProperties("swagger")
public class SwaggerProperties
{
    /**
     * 是否开启swagger
     */
    private Boolean enabled;

    /**
     * swagger会解析的包路径
     **/
    private String basePackage = "";

    /**
     * swagger会解析的url规则
     **/
    private List<String> basePath = new ArrayList<>();

    /**
     * 在basePath基础上需要排除的url规则
     **/
    private List<String> excludePath = new ArrayList<>();

    /**
     * 标题
     **/
    private String title = "";

    /**
     * 描述
     **/
    private String description = "";

    /**
     * 版本
     **/
    private String version = "";

    /**
     * 许可证
     **/
    private String license = "";

    /**
     * 许可证URL
     **/
    private String licenseUrl = "";

    /**
     * 服务条款URL
     **/
    private String termsOfServiceUrl = "";

    /**
     * host信息
     **/
    private String host = "";

    /**
     * 联系人信息
     */
    private Contact contact = new Contact();

    /**
     * 全局统一鉴权配置
     **/
    private Authorization authorization = new Authorization();

    public Boolean getEnabled()
    {
        return enabled;
    }

    public void setEnabled(Boolean enabled)
    {
        this.enabled = enabled;
    }

    public String getBasePackage()
    {
        return basePackage;
    }

    public void setBasePackage(String basePackage)
    {
        this.basePackage = basePackage;
    }

    public List<String> getBasePath()
    {
        return basePath;
    }

    public void setBasePath(List<String> basePath)
    {
        this.basePath = basePath;
    }

    public List<String> getExcludePath()
    {
        return excludePath;
    }

    public void setExcludePath(List<String> excludePath)
    {
        this.excludePath = excludePath;
    }

    public String getTitle()
    {
        return title;
    }

    public void setTitle(String title)
    {
        this.title = title;
    }

    public String getDescription()
    {
        return description;
    }

    public void setDescription(String description)
    {
        this.description = description;
    }

    public String getVersion()
    {
        return version;
    }

    public void setVersion(String version)
    {
        this.version = version;
    }

    public String getLicense()
    {
        return license;
    }

    public void setLicense(String license)
    {
        this.license = license;
    }

    public String getLicenseUrl()
    {
        return licenseUrl;
    }

    public void setLicenseUrl(String licenseUrl)
    {
        this.licenseUrl = licenseUrl;
    }

    public String getTermsOfServiceUrl()
    {
        return termsOfServiceUrl;
    }

    public void setTermsOfServiceUrl(String termsOfServiceUrl)
    {
        this.termsOfServiceUrl = termsOfServiceUrl;
    }

    public String getHost()
    {
        return host;
    }

    public void setHost(String host)
    {
        this.host = host;
    }

    public Contact getContact()
    {
        return contact;
    }

    public void setContact(Contact contact)
    {
        this.contact = contact;
    }

    public Authorization getAuthorization()
    {
        return authorization;
    }

    public void setAuthorization(Authorization authorization)
    {
        this.authorization = authorization;
    }

    public static class Contact
    {
        /**
         * 联系人
         **/
        private String name = "";
        /**
         * 联系人url
         **/
        private String url = "";
        /**
         * 联系人email
         **/
        private String email = "";

        public String getName()
        {
            return name;
        }

        public void setName(String name)
        {
            this.name = name;
        }

        public String getUrl()
        {
            return url;
        }

        public void setUrl(String url)
        {
            this.url = url;
        }

        public String getEmail()
        {
            return email;
        }

        public void setEmail(String email)
        {
            this.email = email;
        }
    }

    public static class Authorization
    {
        /**
         * 鉴权策略ID，需要和SecurityReferences ID保持一致
         */
        private String name = "";

        /**
         * 需要开启鉴权URL的正则
         */
        private String authRegex = "^.*$";

        /**
         * 鉴权作用域列表
         */
        private List<AuthorizationScope> authorizationScopeList = new ArrayList<>();

        private List<String> tokenUrlList = new ArrayList<>();

        public String getName()
        {
            return name;
        }

        public void setName(String name)
        {
            this.name = name;
        }

        public String getAuthRegex()
        {
            return authRegex;
        }

        public void setAuthRegex(String authRegex)
        {
            this.authRegex = authRegex;
        }

        public List<AuthorizationScope> getAuthorizationScopeList()
        {
            return authorizationScopeList;
        }

        public void setAuthorizationScopeList(List<AuthorizationScope> authorizationScopeList)
        {
            this.authorizationScopeList = authorizationScopeList;
        }

        public List<String> getTokenUrlList()
        {
            return tokenUrlList;
        }

        public void setTokenUrlList(List<String> tokenUrlList)
        {
            this.tokenUrlList = tokenUrlList;
        }
    }

    public static class AuthorizationScope
    {
        /**
         * 作用域名称
         */
        private String scope = "";

        /**
         * 作用域描述
         */
        private String description = "";

        public String getScope()
        {
            return scope;
        }

        public void setScope(String scope)
        {
            this.scope = scope;
        }

        public String getDescription()
        {
            return description;
        }

        public void setDescription(String description)
        {
            this.description = description;
        }
    }

/**
 * swagger 资源映射路径
 * 
 */
@Configuration
public class SwaggerWebConfiguration implements WebMvcConfigurer
{
    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry)
    {
        /** swagger-ui 地址 */
        registry.addResourceHandler("/swagger-ui/**")
                .addResourceLocations("classpath:/META-INF/resources/webjars/springfox-swagger-ui/");
    }
}

报错一：: Failed to start bean ‘documentationPluginsBootstrapper’; nested exception is java.lang.NullPointerException

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 *Application.main(Application.java:22)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.springframework.boot.devtools.restart.RestartLauncher.run(RestartLauncher.java:49)
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$1(Comparator.java:469)
	at java.util.TimSort.countRunAndMakeAscending(TimSort.java:355)
	at java.util.TimSort.sort(TimSort.java:234)
	at java.util.Arrays.sort(Arrays.java:1512)
	at java.util.ArrayList.sort(ArrayList.java:1454)
	at java.util.stream.SortedOps$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:1374)
	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)
	... 19 common frames omitted

从报错顺序跟踪源码查看执行步骤

step	操作
1	SpringBoot 启动同时Bean初始化完毕
2	初始化DocumentationPluginsBootstrapper同时将RequestHandlerProvider通过构造器驻入
3	调用DocumentationPluginsBootstrapper start 方法加载Docket插件
4	解析RequestHandlerProvider并将数据存到DocumentationCache中
5	请求Swagger2Controller 的v2/api-docs接口，通过groupName从DocumentationCache中将数据取出，在将数据统一封装到Swagger类中，序列化成json返回给

报错二：No operations defined in spec!

解决

SpringBoot 2.6.0开始，请求路径与SpringMVC处理映射匹配的默认策略已从AntPathMatcher更改为PathPatternParser。可以通过设置spring.mvc.pathmatch.matching-strategy为ant-path-matcher来改变。

除了basePackage包路径配错以外。以下方案可解决以上问题。

/**
 * swagger 在 springboot 2.6.x 不兼容问题的处理
 *
 */
@Component
public class SwaggerBeanPostProcessor implements 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);
        }
    }
}

配置：

spring:
  mvc:
    pathmatch:
      matching-strategy: ant_path_matcher

心如欲壑，后土难填。