Spring catch all route for index.html

Question

I'm developing a spring backend for a react-based single page application where I'm using react-router for client-side routing.

Beside the index.html page the backend serves data on the path /api/**.

In order to serve my index.html from src/main/resources/public/index.html on the root path / of my application I added a resource handler

@Override
public void addResourceHandlers(ResourceHandlerRegistry registry) {
    registry.addResourceHandler("/").addResourceLocations("/index.html");
}

What I want to is to serve the index.html page whenever no other route matches, e.g. when I call a path other than /api.

How do I configure such catch-all route in spring?

Answer 1

Since my react app could use the root as forward target this ended up working for me

@Configuration
public class WebConfiguration extends WebMvcConfigurerAdapter {

  @Override
  public void addViewControllers(ViewControllerRegistry registry) {
      registry.addViewController("/{spring:\w+}")
            .setViewName("forward:/");
      registry.addViewController("/**/{spring:\w+}")
            .setViewName("forward:/");
      registry.addViewController("/{spring:\w+}/**{spring:?!(\.js|\.css)$}")
            .setViewName("forward:/");
  }
}

To be honest I have no idea why it has to be exactly in this specific format to avoid infinite forwarding loop.