java-tutorials/spring-5/src/main/java/com/baeldung/functional/RootServlet.java

package com.baeldung.functional;

import org.springframework.core.io.ClassPathResource;
import org.springframework.http.server.reactive.HttpHandler;
import org.springframework.http.server.reactive.ServletHttpHandlerAdapter;
import org.springframework.util.MultiValueMap;
import org.springframework.web.reactive.function.server.RouterFunction;
import org.springframework.web.reactive.function.server.RouterFunctions;
import org.springframework.web.reactive.function.server.ServerResponse;
import org.springframework.web.server.adapter.WebHttpHandlerBuilder;
import reactor.core.publisher.Flux;
import reactor.core.publisher.Mono;

import java.util.Arrays;
import java.util.List;
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.concurrent.atomic.AtomicLong;

import static org.springframework.web.reactive.function.BodyExtractors.toDataBuffers;
import static org.springframework.web.reactive.function.BodyExtractors.toFormData;
import static org.springframework.web.reactive.function.BodyInserters.fromObject;
import static org.springframework.web.reactive.function.server.RequestPredicates.*;
import static org.springframework.web.reactive.function.server.RouterFunctions.route;
import static org.springframework.web.reactive.function.server.RouterFunctions.toHttpHandler;
import static org.springframework.web.reactive.function.server.ServerResponse.ok;
import org.springframework.web.server.WebHandler;

public class RootServlet extends ServletHttpHandlerAdapter {

    public RootServlet() {
        this(WebHttpHandlerBuilder
          .webHandler((WebHandler) toHttpHandler(routingFunction()))
          .prependFilter(new IndexRewriteFilter())
          .build());
    }

    RootServlet(HttpHandler httpHandler) {
        super(httpHandler);
    }

    private static final Actor BRAD_PITT = new Actor("Brad", "Pitt");
    private static final Actor TOM_HANKS = new Actor("Tom", "Hanks");
    private static final List<Actor> actors = new CopyOnWriteArrayList<>(Arrays.asList(BRAD_PITT, TOM_HANKS));

    private static RouterFunction<?> routingFunction() {

        return route(GET("/test"), serverRequest -> ok().body(fromObject("helloworld")))
          .andRoute(POST("/login"), serverRequest -> serverRequest
            .body(toFormData())
            .map(MultiValueMap::toSingleValueMap)
            .map(formData -> {
                System.out.println("form data: " + formData.toString());
                if ("baeldung".equals(formData.get("user")) && "you_know_what_to_do".equals(formData.get("token"))) {
                    return ok()
                      .body(Mono.just("welcome back!"), String.class)
                      .block();
                }
                return ServerResponse
                  .badRequest()
                  .build()
                  .block();
            }))
          .andRoute(POST("/upload"), serverRequest -> serverRequest
            .body(toDataBuffers())
            .collectList()
            .map(dataBuffers -> {
                AtomicLong atomicLong = new AtomicLong(0);
                dataBuffers.forEach(d -> atomicLong.addAndGet(d
                  .asByteBuffer()
                  .array().length));
                System.out.println("data length:" + atomicLong.get());
                return ok()
                  .body(fromObject(atomicLong.toString()))
                  .block();
            }))
          .and(RouterFunctions.resources("/files/**", new ClassPathResource("files/")))
          .andNest(path("/actor"), route(GET("/"), serverRequest -> ok().body(Flux.fromIterable(actors), Actor.class)).andRoute(POST("/"), serverRequest -> serverRequest
            .bodyToMono(Actor.class)
            .doOnNext(actors::add)
            .then(ok().build())))
          .filter((request, next) -> {
              System.out.println("Before handler invocation: " + request.path());
              return next.handle(request);
          });

    }

}