How to solve the conflict between Springboot2.6.x higher version and Swagger2 version

Problem:

After the Spring Boot 2.6.x version introduces the dependency springfox-boot-starter (Swagger 3.0), an error will be reported when starting the container:

Failed to start bean ‘ documentationPluginsBootstrapper ‘ ; nested exception…

Reason

Springfox assumes that the path matching strategy of Spring MVC is ant-path -matcher, and the default matching strategy of Spring Boot 2.6.x version is path-pattern-matcher, which causes the above error.

Complete solution:

1. pom configuration

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
    <version>2.6.4</version>
</dependency>
<dependency>
    <groupId>io.springfox</groupId>
    <artifactId>springfox-boot-starter</artifactId>
    <version>3.0.0</version>
</dependency>

2. Add Bean

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanPostProcessor;
import org.springframework.stereotype.Component;
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;
 
@Component
public class SwaggerBeanPostProcessor implements BeanPostProcessor {
    @Override
    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
        if (bean instanceof WebMvcRequestHandlerProvider || bean instanceof WebFluxRequestHandlerProvider)
        {
            List<RequestMappingInfoHandlerMapping> handlerMappings = getHandlerMappings(bean);
            customizeSpringfoxHandlerMappings(handlerMappings);
        }
        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);
        }
    }
}

3. swagger configuration class inherits WebMvcConfigurationSupport

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurationSupport;
import springfox.documentation.service.ApiInfo;
import springfox.documentation.spi.DocumentationType;
import springfox.documentation.spring.web.plugins.Docket;
 
@Configuration
public class Swagger2Config extends WebMvcConfigurationSupport {
    @Bean
    public Docket createRestApi() {
        return new Docket(DocumentationType.SWAGGER_2)
                .apiInfo(ApiInfo.DEFAULT);
    }
 
    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry.
                addResourceHandler("/swagger-ui/**")
                .addResourceLocations("classpath:/META-INF/resources/webjars/springfox-swagger-ui/")
                .resourceChain(false);
    }
}

4. Visit http://{ip}:{port}/swagger-ui/index.html

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