解决springboot接入springfox-swagger2遇到的一些问题

springboot接入springfox-swagger2的问题

springfox-swagger2目前最新的版本是3.0，不过已经是2020年的，对springboot新版的适配已经不是多么友好了。

应该是在springboot2.6以上的版本集成springfox-swagger2的时候会有各种问题存在。

一下是一个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 {
    /**
     * 创建API应用
     * apiInfo() 增加API相关信息
     * 通过select()函数返回一个ApiSelectorBuilder实例,用来控制哪些接口暴露给Swagger来展现，
     * 本例采用指定扫描的包路径来定义指定要建立API的目录。
     *
     * @return
     */
    @Bean
    public Docket restApi() {
        return new Docket(DocumentationType.SWAGGER_2)
                .groupName("标准接口")
                .apiInfo(apiInfo("Spring Boot中使用Swagger2构建RESTful APIs", "1.0"))
                .useDefaultResponseMessages(true)
                .forCodeGeneration(false)
                .select()
                .apis(RequestHandlerSelectors.basePackage("com.ithanyu.controller"))
                .paths(PathSelectors.any())
                .build();
    }

    /**
     * 创建该API的基本信息（这些基本信息会展现在文档页面中）
     * 访问地址：http://ip:port/swagger-ui.html
     *
     * @return
     */
    private ApiInfo apiInfo(String title, String version) {
        return new ApiInfoBuilder()
                .title(title)
                .description("更多请关注: 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，这个时候可能会报启动失败

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

这个问题经查询跟springboot的bean初始化有关系，后续的版本更改了相关的东西，具体是什么没有

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);
                }
            }
        };
    }
}

细究，反正参照stackoverflow中的修改方法，加入一下配置类就可以避免错误

加入后启动正常，但是访问swagger的/v2/api-docs接口，发现没有获得数据，接口内容是空的。

这是通过搜索得到有几种解决方案

• 1、ShortVideoSwagger2的配置类需要集成WebMvcConfigurationSupport
• 2、ShortVideoSwagger2的配置类增加@EnableWebMvc注解
• 3、springboot的配置增加增加一下配置

spring:
  mvc:
    pathmatch:
      matching-strategy: ANT_PATH_MATCHER

通过试验得知，这三种接口都可以解决，但是前两种是有副总用的

@EnableWebMvc建议慎用，最后在非springboot项目中使用

前两种解决方案会破坏springboot对springwebmvc的自动装配，导致自定义的一些convertor或者ObjectMapper失效。

目前我的项目中是自定义的ObjectMapper失效。

所以最后使用第三种方式，后期的springboot版本的matching-strategy默认的改为了PATH_PATTERN_PARSER，把它改为ANT_PATH_MATCHER就可以了。

总结

以上为个人经验，希望能给大家一个参考，也希望大家多多支持脚本之家。

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