RxJava的标准Java平台实现：Flow响应式编程

从Java 9开始，Java平台做了大幅度的框架性优化和调整，比如过去Java中的观察者模式标准实现java.util. Observable和java.util. Observer已被标注为废弃，建议开发者使用Java 9的Flow实现观察者模式以及RxJava那一套响应式编程。
 

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Flow;
import java.util.concurrent.SubmissionPublisher;

/**
 * 发送者。
 */
public class Sender implements Flow.Publisher {
    //线程池大小。
    private int THREAD_POOL_SIZE = 5;

    private SubmissionPublisher<String> publisher;

    public Sender() {
        ExecutorService EXECUTOR = Executors.newFixedThreadPool(THREAD_POOL_SIZE);
        publisher = new SubmissionPublisher<>(EXECUTOR, Flow.defaultBufferSize());
    }

    @Override
    public void subscribe(Flow.Subscriber subscriber) {
        getPublisher().subscribe(subscriber);
    }

    public SubmissionPublisher<String> getPublisher() {
        return publisher;
    }

    public void send(String s) {
        getPublisher().submit(s);
    }
}

import java.util.concurrent.Flow;

/**
 * 接受者。
 */
public class Receiver implements Flow.Subscriber<String> {
    private Flow.Subscription subscription;
    private int REQ;

    public Receiver(int req) {
        this.REQ = req;
    }

    @Override
    public void onSubscribe(Flow.Subscription s) {
        this.subscription = s;
        this.subscription.request(REQ);
    }

    @Override
    public void onNext(String item) {
        subscription.request(REQ);

        System.out.println(REQ + " onNext " + item);
    }

    @Override
    public void onError(Throwable throwable) {
        throwable.printStackTrace();
    }

    @Override
    public void onComplete() {
        System.out.println(REQ + " onComplete");
    }
}

测试：

        Sender sender = new Sender();

        Receiver receiver1 = new Receiver(1);
        sender.subscribe(receiver1);

        Receiver receiver2 = new Receiver(2);
        sender.subscribe(receiver2);

        for (int i = 0; i < 10; i++) {
            sender.send(i + "");
        }

输出：

1 onNext 0
2 onNext 0
2 onNext 1
1 onNext 1
2 onNext 2
2 onNext 3
2 onNext 4
2 onNext 5
1 onNext 2
2 onNext 6
1 onNext 3
2 onNext 7
1 onNext 4
2 onNext 8
1 onNext 5
2 onNext 9
1 onNext 6
1 onNext 7
1 onNext 8
1 onNext 9