我们如何在Java 9中使用Publisher-Subscriber来实现Flow API？

Flow API(java.util.concurrent.Flow)已在Java 9中引入。它有助于了解Publisher 和S ubscriber 接口交互以执行所需操作的不同方式。

Flow AP I由发布者，订阅者，订阅和处理器接口组成，它们可以基于反应式流规范。

在下面的示例中，我们可以使用Publisher-Subscriber接口来实现Flow API。

示例

import java.util.concurrent.Flow.Publisher;
import java.util.concurrent.Flow.Subscriber;
import java.util.concurrent.Flow.Subscription;

public class FlowAPITest {
   public static void main(String args[]) {
      Publisher<Integer> publisherSync = new Publisher<Integer>() {   // Create publisher         @Override         public void subscribe(Subscriber<? super Integer> subscriber) {
            for(int i = 0; i < 10; i++) {
               System.out.println(Thread.currentThread().getName() + " | Publishing = " + i);
               subscriber.onNext(i);
            }
            subscriber.onComplete();
         }
      };
      Subscriber<Integer> subscriberSync = new Subscriber<Integer>() {   // Create subscriber         @Override         public void onSubscribe(Subscription subscription) {
         }
         @Override         public void onNext(Integer item) {
            System.out.println(Thread.currentThread().getName() + " | Received = " + item);
            try {
               Thread.sleep(100);
            } catch(InterruptedException e) {
               e.printStackTrace();
            }
         }
         @Override         public void onError(Throwable throwable) {
         }
         @Override         public void onComplete() {
         }
      };
      publisherSync.subscribe(subscriberSync);
   }
}

输出结果

main | Publishing = 0
main | Received = 0
main | Publishing = 1
main | Received = 1
main | Publishing = 2
main | Received = 2
main | Publishing = 3
main | Received = 3
main | Publishing = 4
main | Received = 4
main | Publishing = 5
main | Received = 5
main | Publishing = 6
main | Received = 6
main | Publishing = 7
main | Received = 7
main | Publishing = 8
main | Received = 8
main | Publishing = 9
main | Received = 9