在SpringBoot项目引入Swagger2后，在浏览器地址里输入地址：http://ip:port/swagger-ui.html 报错：

Whitelabel Error Page This application has no explicit mapping for /error, so you are seeing this as a fallback. Mon Dec 06 15:48:30 CST 2021 There was an unexpected error (type=Not Found, status=404). No message available

o.s.web.servlet.PageNotFound : No mapping for GET /swagger-ui.html

经过分析发现由于项目中有配置注解类（@Configuration）继承了WebMvcConfigurationSupport，导致默认的Swagger静态资源被覆盖，而缺失了配置。

可在该继承配置类中，显式添加如下swagger静态资源：

@Override
public void addResourceHandlers(ResourceHandlerRegistry registry) {
          
   
    registry.addResourceHandler("doc.html")
            .addResourceLocations("classpath:/META-INF/resources/");
 
    registry.addResourceHandler("swagger-ui.html")
            .addResourceLocations("classpath:/META-INF/resources/");
    registry.addResourceHandler("/webjars/**")
            .addResourceLocations("classpath:/META-INF/resources/webjars/");
}

不单单swagger，同样的问题，如果因为继承WebMvcConfigurationSupport导致其他默认配置失效。比如，Controller方法上自定义注解失效，则需要在该继承配置类中重写：

@Override
    protected void addArgumentResolvers(List<HandlerMethodArgumentResolver> argumentResolvers) {
          
   
        argumentResolvers.add(...bean...);
    }

原文链接