As detailed previously, we have two approaches, namely functional-based and annotation-based, for implementing a WebFlux application. Annotation-based is similar to Spring MVC, and because of this, we will be using functional-based approach in our sample application:

@Component
public class MovieHandler {
    private final MovieRepository movieRepository;

    public MovieHandler(MovieRepository movieRepository) {
        this.movieRepository = movieRepository;
    }
    public Mono<ServerResponse> listMovies(ServerRequest request) {
        // fetch all Movies from repository
        Flux<Movie> movies = movieRepository.listMovies();
        // build response
        return 
            ServerResponse.ok().contentType(MediaType.APPLICATION_JSON)
            .body(movies, Movie.class);
    }
    //...Other methods
}

The class is quite straightforward and uses a repository class for data structure query and manipulation. Each method accomplishes the functionality, and finally returns Mono<ServerResponse>. Another important aspect of WebFlux in functional-based programming is the routing configuration class, as follows:

@Configuration
public class RouterConfig {

    @Bean
    public RouterFunction<ServerResponse> routerFunction1(MovieHandler 
        movieHandler) {
      return 
        route(GET("/").and(accept(MediaType.APPLICATION_JSON)), 
            movieHandler::listMovies)
        .andRoute(GET("/api/movie").and(accept(MediaType.APPLICATION_JSON)), 
            movieHandler::listMovies)
        .andRoute(GET("/api/movie/{id}").and(accept(MediaType.APPLICATION_JSON)), 
            movieHandler::getMovieById)
        .andRoute(POST("/api/movie").and(accept(MediaType.APPLICATION_JSON)), 
            movieHandler::saveMovie)
        .andRoute(PUT("/api/movie/{id}").and(accept(MediaType.APPLICATION_JSON)), 
            movieHandler::putMovie)
        .andRoute(DELETE("/api/movie/{id}")
            .and(accept(MediaType.APPLICATION_JSON)), movieHandler::deleteMovie);
    }
}

This is the class that looks at the request and routes it to the appropriate handler method. In your application, you can have any number of router configuration files.