Spring MVC mapping resources and index - spring

Question

I have a resource path set up
registry.addResourceHandler("/assets/**").addResourceLocations("/WEB-INF/assets/");
and the DispatcherServlet mapped to /
Now I'm trying to add the index page, which I believe should be mapped to /.
However, when I add the index page mapping /, everything gets mapped there including my assets directory, but not including other defined response mappings. Ideally, I only want to map requests to exactly the context root.
I have this working with a view controller, but that means that I cannot execute any controller logic before returning the view.
#Configuration
#EnableWebMvc
#ComponentScan(basePackages = "com.myco")
public class SpringConfig extends WebMvcConfigurerAdapter {
#Override
public void addViewControllers(ViewControllerRegistry registry) {
registry.addViewController("/").setViewName("index");
}

Answer 1

Let's break down your configuration here since I believe your have more than one problem.
Firstly, this line
registry.addResourceHandler("/assets/**").addResourceLocations("/WEB-INF/assets/");
configure a mapping between any sub-path of /assets and the assets directory inside your WEB-INF directory. So when you say "everything gets mapped there including my assets directory", that's the expected behavior.
If this directory is where your views can be found in, that is probably not what you want since you generally don't want your raw views to be publicly exposed. If you need any assets to be publicly exposed (css, js, images, ...), you should create some kind of hierarchy and only publicly expose the content directly needed by clients browsing your app.
For example, inside your assets directory, you could have a public directory and you could fix your mapping like :
registry.addResourceHandler("/assets/**").addResourceLocations("/WEB-INF/assets/public/");
Secondly, let's take a look at the documentation for the addViewControllers of any WebMvcConfigurer :
Add view controllers to create a direct mapping between a URL path and
view name without the need for a controller in between.
So yeah, as you said it, you won't be able to execute any controller logic before returning the view.
I believe what's missing in your configuration is a ViewResolver so that your controllers will be able to resolve views by their name without you needing to configure a direct mapping with addViewControllers (preventing any business logic to be executed in-between).

Answer 2

Add this in your SpringConfig
#Bean
public ViewResolver viewResolver() {
InternalResourceViewResolver viewResolver = new InternalResourceViewResolver();
viewResolver.setPrefix("/WEB-INF/views/");
viewResolver.setSuffix(".jsp");
return viewResolver;
}
Add a controller in a package where spring does componentscan. For example
#Controller
public class MainController {
#RequestMapping(value = "/")
public String index(Model model){
// implements business logic
return "index";
}
}
And in /WEB-INF/views you add your view called index.jsp