Android Retrofit 2 + RxJava:听听层出不穷

Question

我可以使用Retrofit + RxJava来聆听无尽的流吗？例如Twitter流.我有的是这个:

public interface MeetupAPI {
    @GET("http://stream.meetup.com/2/rsvps/")
    Observable<RSVP> getRSVPs();
}

MeetupAPI api = new Retrofit.Builder()
            .baseUrl(MeetupAPI.RSVP_API)
            .addCallAdapterFactory(RxJavaCallAdapterFactory.create())
            .addConverterFactory(GsonConverterFactory.create())
            .build()
            .create(MeetupAPI.class);

api.getRSVPs()
        .subscribeOn(Schedulers.newThread())
        .observeOn(AndroidSchedulers.mainThread())
        .subscribe(rsvp -> Log.d(TAG, "got rsvp"),
                error -> Log.d(TAG, "error: " + error),
                () -> Log.d(TAG, "onComplete"));

但在解析第一个对象后调用"onComplete".有没有办法告诉Retrofit保持开放直到另行通知？

Answer 1

我的解决方案:

您可以使用@Streaming批注:

public interface ITwitterAPI {

    @GET("/2/rsvps")
    @Streaming
    Observable<ResponseBody> twitterStream();
}

ITwitterAPI api = new Retrofit.Builder()
          .baseUrl("http://stream.meetup.com")
          .addCallAdapterFactory(RxJavaCallAdapterFactory.create())
          .build().create(ITwitterAPI.class);

随着@Streaming我们可以得到原始输入从ResponseBody.

这里我的函数用于通过事件将行换行:

public static Observable<String> events(BufferedSource source) {
    return Observable.create(new Observable.OnSubscribe<String>() {
        @Override
        public void call(Subscriber<? super String> subscriber) {
            try {
                while (!source.exhausted()) {
                    subscriber.onNext(source.readUtf8Line());
                }
                subscriber.onCompleted();
            } catch (IOException e) {
                e.printStackTrace();
                subscriber.onError(e);
            }
        }
    });
}

结果用法:

api.twitterStream()
  .flatMap(responseBody -> events(responseBody.source()))
  .subscribe(System.out::println);

关于优雅地停止

当我们取消订阅时,改造将关闭输入流.但是不可能从输入流本身检测输入流是否关闭,所以只有这样 - 尝试从流中读取 - 我们得到Socket closed消息异常.我们可以将此异常解释为结束:

        @Override
        public void call(Subscriber<? super String> subscriber) {
            boolean isCompleted = false;
            try {
                while (!source.exhausted()) {
                    subscriber.onNext(source.readUtf8Line());
                }
            } catch (IOException e) {
                if (e.getMessage().equals("Socket closed")) {
                    isCompleted = true;
                    subscriber.onCompleted();
                } else {
                    throw new UncheckedIOException(e);
                }
            }
            //if response end we get here
            if (!isCompleted) {
                subscriber.onCompleted();
            }
        }

如果连接因响应结束而关闭,我们没有任何例外.在这里isCompleted检查.如果我错了,请告诉我:)