how to specify welcome-file-list in WebApplicationInitializer.onStartup()

Question

Currently I have a web application where we are using web.xml to configure the application. The web.xml has welcome-file-list.

<web-app>  
   ...
   <welcome-file-list>  
     <welcome-file>home.html</welcome-file>  
   </welcome-file-list>  
</web-app>  

We are planning to use spring framework and use java class for application configuration.

class MyApplication extends WebApplicationInitializer {
    public void onStartUp(ServletContext context){
        ...
    }
}

How do I specify welcome-file-list in this java class?

Answer 1

While developing Spring MVC application with pure Java Based Configuration, we can set the home page by making our application configuration class extending the WebMvcConfigurerAdapter class and override the addViewControllers method where we can set the default home page as described below.

@Configuration
@EnableWebMvc
@ComponentScan(basePackages = { "com.myapp.controllers" })
public class ApplicationConfig extends WebMvcConfigurerAdapter {

  @Bean
  public InternalResourceViewResolver getViewResolver() {
    InternalResourceViewResolver viewResolver = new InternalResourceViewResolver();
    viewResolver.setPrefix("/WEB-INF/view/");
    viewResolver.setSuffix(".jsp");
    return viewResolver;
  }

  @Override
  public void addViewControllers(ViewControllerRegistry registry) {
    registry.addViewController("/").setViewName("home");
  }

}

It returns home.jsp view which can be served as home page. No need to create a custom controller logic to return the home page view.

The JavaDoc for addViewControllers method says -

Configure simple automated controllers pre-configured with the response status code and/or a view to render the response body. This is useful in cases where there is no need for custom controller logic -- e.g. render a home page, perform simple site URL redirects, return a 404 status with HTML content, a 204 with no content, and more.

2nd way - For static HTML file home page we can use the code below in our configuration class. It will return index.html as a home page -

    @Override
    public void addViewControllers(ViewControllerRegistry registry) {
        registry.addViewController("/").setViewName("forward:/index.html");
    }

3rd way - The request mapping "/" below will also return home view which can be served as a home page for an app. But the above ways are recommended.

@Controller
public class UserController {
    @RequestMapping(value = { "/" })
    public String homePage() {
        return "home";
    }
}