springboot接入springfox-swagger2的問題

springfox-swagger2目前最新的版本是3.0，不過已經(jīng)是2020年的，對springboot新版的適配已經(jīng)不是多么友好了。

應(yīng)該是在springboot2.6以上的版本集成springfox-swagger2的時候會有各種問題存在。

一下是一個springboot2.7.10集成swagger的例子：

1、引入springfox-swagger的jar文件

<!--swagger-->
        <dependency>
            <groupId>io.springfox</groupId>
            <artifactId>springfox-boot-starter</artifactId>
            <version>3.0.0</version>
        </dependency>

2、配置swagger的配置文件(SwaggerConfig.java)

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
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;

/**
 * @ClassName swaggerConfig
 * @Description: TODO
 * @Author:1276046082@qq.com
 */

@Configuration
@EnableOpenApi
public class SwaggerConfig {
    /**
     * 創(chuàng)建API應(yīng)用
     * apiInfo() 增加API相關(guān)信息
     * 通過select()函數(shù)返回一個ApiSelectorBuilder實例,用來控制哪些接口暴露給Swagger來展現(xiàn)，
     * 本例采用指定掃描的包路徑來定義指定要建立API的目錄。
     *
     * @return
     */
    @Bean
    public Docket restApi() {
        return new Docket(DocumentationType.SWAGGER_2)
                .groupName("標(biāo)準(zhǔn)接口")
                .apiInfo(apiInfo("Spring Boot中使用Swagger2構(gòu)建RESTful APIs", "1.0"))
                .useDefaultResponseMessages(true)
                .forCodeGeneration(false)
                .select()
                .apis(RequestHandlerSelectors.basePackage("com.ithanyu.controller"))
                .paths(PathSelectors.any())
                .build();
    }

    /**
     * 創(chuàng)建該API的基本信息（這些基本信息會展現(xiàn)在文檔頁面中）
     * 訪問地址：http://ip:port/swagger-ui.html
     *
     * @return
     */
    private ApiInfo apiInfo(String title, String version) {
        return new ApiInfoBuilder()
                .title(title)
                .description("更多請關(guān)注: https://blog.csdn.net/zy1276046082")
                .termsOfServiceUrl("https://blog.csdn.net/zy1276046082")
                .contact(new Contact("zyhanyu", "https://blog.csdn.net/zy1276046082", "1276046082@qq.com"))
                .version(version)
                .build();
    }
}

如果使用低版本的springboot比如2.6以下的，基本上都可以成功的。

但是使用2.6以上版本，這個時候可能會報啟動失敗

Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
2023-10-24 23:26:19.235 ERROR 28432 --- [           main] o.s.boot.SpringApplication               : Application run failed

org.springframework.context.ApplicationContextException: Failed to start bean 'documentationPluginsBootstrapper'; nested exception is java.lang.NullPointerException
    at org.springframework.context.support.DefaultLifecycleProcessor.doStart(DefaultLifecycleProcessor.java:182) ~[spring-context-5.3.30.jar:5.3.30]
    at org.springframework.context.support.DefaultLifecycleProcessor.access$200(DefaultLifecycleProcessor.java:54) ~[spring-context-5.3.30.jar:5.3.30]
    at org.springframework.context.support.DefaultLifecycleProcessor$LifecycleGroup.start(DefaultLifecycleProcessor.java:357) ~[spring-context-5.3.30.jar:5.3.30]
    at java.lang.Iterable.forEach(Iterable.java:75) ~[na:1.8.0_201]
    at org.springframework.context.support.DefaultLifecycleProcessor.startBeans(DefaultLifecycleProcessor.java:156) ~[spring-context-5.3.30.jar:5.3.30]
    at org.springframework.context.support.DefaultLifecycleProcessor.onRefresh(DefaultLifecycleProcessor.java:124) ~[spring-context-5.3.30.jar:5.3.30]
    at org.springframework.context.support.AbstractApplicationContext.finishRefresh(AbstractApplicationContext.java:938) ~[spring-context-5.3.30.jar:5.3.30]
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:586) ~[spring-context-5.3.30.jar:5.3.30]
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:147) ~[spring-boot-2.7.17.jar:2.7.17]
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:732) [spring-boot-2.7.17.jar:2.7.17]
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:409) [spring-boot-2.7.17.jar:2.7.17]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:308) [spring-boot-2.7.17.jar:2.7.17]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1300) [spring-boot-2.7.17.jar:2.7.17]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1289) [spring-boot-2.7.17.jar:2.7.17]
    at com.ithanyu.Application.main(Application.java:17) [classes/:na]
Caused by: java.lang.NullPointerException: null
    at springfox.documentation.spring.web.WebMvcPatternsRequestConditionWrapper.getPatterns(WebMvcPatternsRequestConditionWrapper.java:56) ~[springfox-spring-webmvc-3.0.0.jar:3.0.0]
    at springfox.documentation.RequestHandler.sortedPaths(RequestHandler.java:113) ~[springfox-core-3.0.0.jar:3.0.0]
    at springfox.documentation.spi.service.contexts.Orderings.lambda$byPatternsCondition$3(Orderings.java:89) ~[springfox-spi-3.0.0.jar:3.0.0]
    at java.util.Comparator.lambda$comparing$77a9974f$1(Comparator.java:469) ~[na:1.8.0_201]
    at java.util.TimSort.countRunAndMakeAscending(TimSort.java:355) ~[na:1.8.0_201]
    at java.util.TimSort.sort(TimSort.java:220) ~[na:1.8.0_201]
    at java.util.Arrays.sort(Arrays.java:1512) ~[na:1.8.0_201]
    at java.util.ArrayList.sort(ArrayList.java:1462) ~[na:1.8.0_201]
    at java.util.stream.SortedOps$RefSortingSink.end(SortedOps.java:387) ~[na:1.8.0_201]
    at java.util.stream.Sink$ChainedReference.end(Sink.java:258) ~[na:1.8.0_201]
    at java.util.stream.Sink$ChainedReference.end(Sink.java:258) ~[na:1.8.0_201]
    at java.util.stream.Sink$ChainedReference.end(Sink.java:258) ~[na:1.8.0_201]
    at java.util.stream.Sink$ChainedReference.end(Sink.java:258) ~[na:1.8.0_201]
    at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:482) ~[na:1.8.0_201]
    at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:471) ~[na:1.8.0_201]
    at java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:708) ~[na:1.8.0_201]
    at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) ~[na:1.8.0_201]
    at java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:499) ~[na:1.8.0_201]
    at springfox.documentation.spring.web.plugins.WebMvcRequestHandlerProvider.requestHandlers(WebMvcRequestHandlerProvider.java:81) ~[springfox-spring-webmvc-3.0.0.jar:3.0.0]
    at java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:193) ~[na:1.8.0_201]
    at java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1382) ~[na:1.8.0_201]
    at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:481) ~[na:1.8.0_201]
    at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:471) ~[na:1.8.0_201]
    at java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:708) ~[na:1.8.0_201]
    at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) ~[na:1.8.0_201]
    at java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:499) ~[na:1.8.0_201]
    at springfox.documentation.spring.web.plugins.AbstractDocumentationPluginsBootstrapper.withDefaults(AbstractDocumentationPluginsBootstrapper.java:107) ~[springfox-spring-web-3.0.0.jar:3.0.0]
    at springfox.documentation.spring.web.plugins.AbstractDocumentationPluginsBootstrapper.buildContext(AbstractDocumentationPluginsBootstrapper.java:91) ~[springfox-spring-web-3.0.0.jar:3.0.0]
    at springfox.documentation.spring.web.plugins.AbstractDocumentationPluginsBootstrapper.bootstrapDocumentationPlugins(AbstractDocumentationPluginsBootstrapper.java:82) ~[springfox-spring-web-3.0.0.jar:3.0.0]
    at springfox.documentation.spring.web.plugins.DocumentationPluginsBootstrapper.start(DocumentationPluginsBootstrapper.java:100) ~[springfox-spring-web-3.0.0.jar:3.0.0]
    at org.springframework.context.support.DefaultLifecycleProcessor.doStart(DefaultLifecycleProcessor.java:179) ~[spring-context-5.3.30.jar:5.3.30]
    ... 14 common frames omitted

Process finished with exit code 1

這個問題經(jīng)查詢跟springboot的bean初始化有關(guān)系，后續(xù)的版本更改了相關(guān)的東西，具體是什么沒有

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanPostProcessor;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.lang.NonNull;
import org.springframework.util.ReflectionUtils;
import org.springframework.web.servlet.mvc.method.RequestMappingInfoHandlerMapping;
import springfox.documentation.spring.web.plugins.WebFluxRequestHandlerProvider;
import springfox.documentation.spring.web.plugins.WebMvcRequestHandlerProvider;

import java.lang.reflect.Field;
import java.util.List;
import java.util.stream.Collectors;

/**
 * swagger config
 *
 * @author zxl
 * @date 2023-05-16
 */
@Configuration
public class SwaggerConfig {

    @Bean
    public BeanPostProcessor springfoxHandlerProviderBeanPostProcessor() {
        return new BeanPostProcessor() {

            @Override
            public Object postProcessAfterInitialization(@NonNull  Object bean, @NonNull 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");
                    assert field != null;
                    field.setAccessible(true);
                    return (List<RequestMappingInfoHandlerMapping>) field.get(bean);
                } catch (IllegalArgumentException | IllegalAccessException e) {
                    throw new IllegalStateException(e);
                }
            }
        };
    }
}

細究，反正參照stackoverflow中的修改方法，加入一下配置類就可以避免錯誤

加入后啟動正常，但是訪問swagger的/v2/api-docs接口，發(fā)現(xiàn)沒有獲得數(shù)據(jù)，接口內(nèi)容是空的。

這是通過搜索得到有幾種解決方案

• 1、ShortVideoSwagger2的配置類需要集成WebMvcConfigurationSupport
• 2、ShortVideoSwagger2的配置類增加@EnableWebMvc注解
• 3、springboot的配置增加增加一下配置

spring:
  mvc:
    pathmatch:
      matching-strategy: ANT_PATH_MATCHER

通過試驗得知，這三種接口都可以解決，但是前兩種是有副總用的

@EnableWebMvc建議慎用，最后在非springboot項目中使用

前兩種解決方案會破壞springboot對springwebmvc的自動裝配，導(dǎo)致自定義的一些convertor或者ObjectMapper失效。

目前我的項目中是自定義的ObjectMapper失效。

所以最后使用第三種方式，后期的springboot版本的matching-strategy默認(rèn)的改為了PATH_PATTERN_PARSER，把它改為ANT_PATH_MATCHER就可以了。

總結(jié)

以上為個人經(jīng)驗，希望能給大家一個參考，也希望大家多多支持腳本之家。

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