如何使用反应式 android 和改造发出多个请求 [英] How to make multiple requests with reactive android and retrofit

问题描述

我有调用 getShops() 方法的演示者.

I have presenter which calls getShops() method.

Observable<List<Shop>> observable = interactor.getData();
        Subscription subscription = observable
                .subscribeOn(Schedulers.newThread())
                .observeOn(AndroidSchedulers.mainThread())
                .subscribe(new Subscriber<List<Shop>>() {
                    @Override
                    public void onCompleted() {
                        view.hideProgress();
                    }

                    @Override
                    public void onError(Throwable e) {
                        super.onError(e);
                        view.hideProgress();
                    }

                    @Override
                    public void onNext(List<Shop> shops) {
                        handleShops(shops);
                        view.onSuccess();
                    }
                });
        composite.add(subscription);

在数据层中，我有 Interactor，它通过 Retrofit 向服务器发出请求并返回 List.

In data layer I have Interactor which makes request to server with Retrofit and return List<Shop>.

@Override
public Observable<List<Shop>> getData() {
    return api.getShops(pageNum).map(new Func1<ShopWrapper, List<Shop>>() {
        @Override
        public List<Shop> call(ShopWrapper wrapper) {
            return wrapper.getShops();
        }
    });
}

问题是我需要用不同的页面参数发出多个相同的请求，因为服务器每页返回N家商店，我需要收集所有商店然后返回Observable>给演示者.

The problem is that I need to make multiple identical requests with different page parameter, because server returns N shops per page, and I need collect all shops and then return the Observable<List<Shop>> to presenter.

我是响应式编程的新手，也许有一些运算符可以做到这一点.

I'm new to Reactive programming, maybe there is some operator which allows to do this.

任何帮助将不胜感激.

推荐答案

只需使用 Observable.range 和 concatMap 调用即可.如果你不知道你的上限，你可以在某些条件下使用 takeUntil.

Just use Observable.range and concatMap your calls with it. If you don't know your upper range, you can use takeUntil with some condition.

像这样:

Observable.range(0, Integer.MAX_VALUE)
            .concatMap(pageNum -> api.getShops(pageNum).map(doYourMapping))
            .takeUntil(shops -> someCondition);

如果你只想要一个 onNext 调用，你可以在 takeUntil 之后添加:

If you want only one onNext call you can add this after takeUntil:

.flatMapIterable(shops -> shops)
.toList();

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