swagger-ui No mapping found for HTTP request

Question

I'm trying to document and existing Rest API a Spring MVC project (NOT spring boot!).

My application is called api so http://localhost:9090/api would be the root endpoint. Because I'm using spring-data-rest, on that URL I can see the json of all my exposed repositories. So far so good.

I can also access the swagger JSON http://localhost:9090/api/v2/api-docs

The problem

I can't access the swagger-UI component on http://localhost:9090/api/swagger-ui.html . It gives me

WARN  org.springframework.web.servlet.PageNotFound- No mapping found for HTTP request with URI [/api/swagger-ui.html] in DispatcherServlet with name 'dispatcher'

Checking the spring logs when starting tomcat I can see something weird

DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory- Finished creating instance of bean 'swaggerApiListingReader'
DEBUG org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping- Rejected bean name 'swaggerConfig': no URL paths identified
DEBUG org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping- Rejected bean name 'swagger2Controller': no URL paths identified
DEBUG org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping- Rejected bean name 'swaggerMediaTypeReader': no URL paths identified
DEBUG org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping- Rejected bean name 'swaggerOperationModelsProvider': no URL paths identified
DEBUG org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping- Rejected bean name 'swaggerOperationResponseClassReader': no URL paths identified
DEBUG org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping- Rejected bean name 'swaggerOperationTagsReader': no URL paths identified
DEBUG org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping- Rejected bean name 'swaggerResponseMessageReader': no URL paths identified
DEBUG org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping- Rejected bean name 'swaggerParameterDescriptionReader': no URL paths identified
DEBUG org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping- Rejected bean name 'swaggerExpandedParameterBuilder': no URL paths identified
DEBUG org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping- Rejected bean name 'swaggerApiListingReader': no URL paths identified
DEBUG org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping- Rejected bean name 'swaggerProperties': no URL paths identified
DEBUG org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping- Rejected bean name 'springfox.documentation.swagger.configuration.SwaggerCommonConfiguration': no URL paths identified
DEBUG org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping- Rejected bean name 'springfox.documentation.swagger2.configuration.Swagger2DocumentationConfiguration': no URL paths identified
DEBUG org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping- Rejected bean name 'swagger2Module': no URL paths identified

That seems to indicate the for some reason swaggerController is not associated to any URL, hence the 404 error.

These are the version I'm working with

  <spring.version>4.2.8.RELEASE</spring.version>
  <spring-data.version>Gosling-SR4</spring-data.version>
  <spring-data-rest>2.4.6.RELEASE</spring-data-rest> 
   <dependency>
        <groupId>io.springfox</groupId>
        <artifactId>springfox-swagger2</artifactId>
        <version>2.6.1</version>
    </dependency>
    <dependency>
        <groupId>io.springfox</groupId>
        <artifactId>springfox-swagger-ui</artifactId>
        <version>2.6.1</version>
    </dependency>
    <dependency>
        <groupId>io.springfox</groupId>
        <artifactId>springfox-data-rest</artifactId>
        <version>2.6.1</version>
    </dependency>

This is my Java conf. Worth pointing out that the method addResourceHandlers NEVER GETS executed

    @Configuration
    @EnableSwagger2
    @EnableWebMvc

  @Import({springfox.documentation.spring.data.rest.configuration.SpringDataRestConfiguration.class})
public class SwaggerConfig extends WebMvcConfigurerAdapter {
    @Bean
    public Docket api() {
        return new Docket(DocumentationType.SWAGGER_2)
                .select()
                .apis(RequestHandlerSelectors.any())
                .paths(PathSelectors.any())
                .build();
    }

    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {

        System.out.println("******************************Configuring swagger resource handler");
        registry.addResourceHandler("swagger-ui.html")
                .addResourceLocations("classpath:/META-INF/resources/");
        registry.addResourceHandler("/webjars/**")
                .addResourceLocations("classpath:/META-INF/resources/webjars/");
    }
}

Any suggestions? In short, swagger-ui does not work.

Answer 1

This solution is courtesy this answer by @oksett

Create a configuration class, which extends WebMvcConfigurerAdapter and override the following methods:

If Using Spring 5, instead of extends WebMvcConfigurerAdapter implements WebMvcConfigurer

@Override
public void addViewControllers(ViewControllerRegistry registry) {
    registry.addRedirectViewController("/api/v2/api-docs", "/v2/api-docs");
    registry.addRedirectViewController("/api/swagger-resources/configuration/ui", "/swagger-resources/configuration/ui");
    registry.addRedirectViewController("/api/swagger-resources/configuration/security", "/swagger-resources/configuration/security");
    registry.addRedirectViewController("/api/swagger-resources", "/swagger-resources");
}

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

In your case you need to add and implementation of addViewControllers to SwaggerConfig. Also note the changes in the addResourceHandlers method to prepend /api to the the rescue handler location.

You should now be able to access into my swagger-ui.html @ http://localhost:9090/api/swagger-ui.html