WebClient: Spring的新的HTTP反應式客戶端 - spring.io

package bootiful.httpclient.webclient;

import lombok.ToString;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.context.event.ApplicationReadyEvent;
import org.springframework.context.ApplicationListener;
import org.springframework.context.annotation.Bean;
import org.springframework.core.io.buffer.DataBuffer;
import org.springframework.core.io.buffer.DataBufferUtils;
import org.springframework.http.MediaType;
import org.springframework.scheduling.annotation.EnableAsync;
import org.springframework.web.reactive.function.client.WebClient;
import reactor.core.publisher.Mono;

import java.net.URI;
import java.nio.file.Path;
import java.util.ArrayList;
import java.util.Collection;

import static java.nio.file.StandardOpenOption.CREATE;

@EnableAsync
@SpringBootApplication
public class BootifulApplication {

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

    @Bean
    WebClient webClient(WebClient.Builder builder) {
        return builder//
                .filter(//
                        (clientRequest, exchangeFunction) -> exchangeFunction//
                                .exchange(clientRequest)//
                                .doOnNext(response -> System.out.println("got a WebClient response: " + response))//
                ) //
                .build();
    }

    @Bean
    ApplicationListener<ApplicationReadyEvent> ready(@Value("file://${user.home}/Desktop/output.zip") Path output,
            WebClient client) {

        return event -> {

            // initialize a new Spring Boot project .zip archive
            Mono<DataBuffer> db = client.get()//
                    .uri(URI.create("https://start.spring.io/starter.zip"))//
                    .accept(MediaType.APPLICATION_OCTET_STREAM)//
                    .retrieve()//
                    .bodyToMono(DataBuffer.class);

            // gets written out to ~/output.zip
            Mono<Boolean> write = DataBufferUtils.write(db, output, CREATE).thenReturn(true);

            // enumerate all the active Spring projects using the
            // JSON API while we're at it...
            Mono<ProjectsResponse> json = client//
                    .get()//
                    .uri(URI.create("https://spring.io/api/projects"))//
                    .retrieve()//
                    .bodyToMono(ProjectsResponse.class);

            // look ma! No threading code! this will launch both network
            // calls (the .zip and the json) at the same time
            Mono.zip(write, json).subscribe(tuple -> enumerate(tuple.getT2()));
        };
    }

    private void enumerate(ProjectsResponse pr) {
        pr._embedded //
                .projects //
                        .stream() //
                        .filter(p -> p.status.equalsIgnoreCase("active")) //
                        .forEach(project -> System.out.println(project.toString()));
    }

}

@ToString
class ProjectsResponse {

    public Embedded _embedded = new Embedded();

    @ToString
    public static class Project {

        public String name, slug, status, repositoryUrl;

    }

    @ToString
    public static class Embedded {

        public Collection<Project> projects = new ArrayList<>();

    }

}