Super small example demonstrating a few Spring out of the box things - mostly for i18n / property bits.

Not quite prod-ready code - i.e a bit rough round the edges, but just to demonstrate the concepts.

https://docs.spring.io/spring-boot/docs/current/reference/html/spring-boot-features.html#boot-features-external-config-java-bean-binding

Useful for binding directly to a fragment of yaml - esp in cases where there's some simple static values or bits that are easy to read describe in a nested block / keyed by some values.

https://docs.spring.io/spring-boot/docs/current/reference/html/spring-boot-features.html#boot-features-internationalization

Just to demonstrate programmatic usage of MessageSource for translating message keys with optional args.

Often templates are used in conjunction which wouldn't require explicit usage, but sometimes (i.e when creating APIs in backend-for-frontend type service it can be handy to use in such a manner).

You would'nt normally hand craft / edit the resource bundle files - perhaps a tool like Crowdin would generate these in CI using a translator service as an input.

https://docs.spring.io/spring-framework/docs/current/spring-framework-reference/web.html#mvc-localeresolver

Spring has various strategies to determine locale of the current request. The most commonly used and one of the default registered is to parse the Accept Language header on an inbound http request. This will automatically get bound to a parameter of a controller method if specified.

Run the app locally, and head to:

localhost:8080/fun

Set the Accept-Language to your favourite language for even more fun.