[JAVA] Try the Spring WebFlux tutorial

Introduction

Please forgive the point that it is a poor description because it is the first post. : bow_tone1: I recently learned the word "Spring WebFlux", so I'll touch on it through the tutorial.

What is WebFlux

Spring WebFlux is a web framework provided by Spring and performs non-blocking processing. You can do it. Roughly speaking, I understood that it is a "mechanism that can process efficiently while saving threads".

What to do this time

I would like to try the tutorial on the following page. Building a Reactive RESTful Web Service

Development environment ・ Visual Studio Code ・ AdoptOpenJDK 11.0.5 + 10

1. Preparation

Clone the source code locally.

$ git clone https://github.com/spring-guides/gs-reactive-rest-service.git
Cloning into 'gs-reactive-rest-service'...
remote: Enumerating objects: 21, done.
remote: Counting objects: 100% (21/21), done.
remote: Compressing objects: 100% (15/15), done.
remote: Total 822 (delta 6), reused 14 (delta 5), pack-reused 801
Receiving objects: 100% (822/822), 408.59 KiB | 771.00 KiB/s, done.
Resolving deltas: 100% (553/553), done.

Since it is developed with vscode, open the developed folder. Menu: File> Open> cloned gs-reactive-rest-service folder

2. Create a WebFlux Handler.

Create a new GreetingHandler.java under ʻinitial / src / main / java / hello`.

GreetingHandler.java

package hello;

import org.springframework.http.MediaType;
import org.springframework.stereotype.Component;
import org.springframework.web.reactive.function.BodyInserters;
import org.springframework.web.reactive.function.server.ServerRequest;
import org.springframework.web.reactive.function.server.ServerResponse;

import reactor.core.publisher.Mono;

@Component
public class GreetingHandler {

  public Mono<ServerResponse> hello(ServerRequest request) {
    return ServerResponse.ok().contentType(MediaType.TEXT_PLAIN)
      .body(BodyInserters.fromObject("Hello, Spring!"));
  }
}

3. Make a Router.

Create a new GreetingRouter.java under ʻinitial / src / main / java / hello`.

GreetingRouter.java

package hello;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.MediaType;
import org.springframework.web.reactive.function.server.RequestPredicates;
import org.springframework.web.reactive.function.server.RouterFunction;
import org.springframework.web.reactive.function.server.RouterFunctions;
import org.springframework.web.reactive.function.server.ServerResponse;

@Configuration
public class GreetingRouter {

  @Bean
  public RouterFunction<ServerResponse> route(GreetingHandler greetingHandler) {

    return RouterFunctions
      .route(RequestPredicates.GET("/hello").and(RequestPredicates.accept(MediaType.TEXT_PLAIN)), greetingHandler::hello);
  }
}

4. Create a Web Client.

Create a new GreetingWebClient.java under ʻinitial / src / main / java / hello`.

GreetingWebClient

package hello;

import org.springframework.http.MediaType;
import org.springframework.web.reactive.function.client.ClientResponse;
import org.springframework.web.reactive.function.client.WebClient;

import reactor.core.publisher.Mono;

public class GreetingWebClient {
  private WebClient client = WebClient.create("http://localhost:8080");

  private Mono<ClientResponse> result = client.get()
      .uri("/hello")
      .accept(MediaType.TEXT_PLAIN)
      .exchange();

  public String getResult() {
    return ">> result = " + result.flatMap(res -> res.bodyToMono(String.class)).block();
  }
}

5. Allow the app to run.

ʻCreate a new Application.java under initial / src / main / java / hello`.

Application.java

package hello;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class Application {

  public static void main(String[] args) {
    SpringApplication.run(Application.class, args);

    GreetingWebClient gwc = new GreetingWebClient();
    System.out.println(gwc.getResult());
  }
}

6. Try it.

Right-click on Application.java and select Run and you will see the following message in the terminal: >> result = Hello, Spring WebFlux! Similarly, if you open http: // localhost: 8080 / hello in your browser, you will see the same message.

Finally

Thank you for reading to the end. I'm interested in programming similar to myself, but I hope it helps people who have no clue.