结合 RxTextView Observable 和 Retrofit Observable

作为 RxAndroid 入门的一个示例，我正在尝试实现一个搜索框，当用户插入某些内容时，该搜索框会触发休息调用。

到目前为止我有两个工作部分。首先观察EditText视图...

RxTextView.textChangeEvents(searchEditText)
    .debounce(400, TimeUnit.MILLISECONDS)
    .observeOn(AndroidSchedulers.mainThread())
    .subscribe(new Observer<TextViewTextChangeEvent>() {
            @Override
            public void onCompleted() {
                Timber.d("onCompleted");
            }

            @Override
            public void onError(Throwable e) {
                Timber.e(e, "onError");
                }

            @Override
            public void onNext(TextViewTextChangeEvent e) {
                Timber.d("onNext" + e.text().toString());
            }
        });

...第二部分通过使用 Retrofit 服务调用 REST API：

APIManager.getService().searchRestaurants("test")
        .subscribeOn(Schedulers.io())
        .observeOn(AndroidSchedulers.mainThread())
        .subscribe(new Observer<List<Restaurant>>() {
            @Override
            public void onCompleted() {
                Timber.d("onCompleted");
            }

            @Override
            public void onError(Throwable e) {
                Timber.e(e, "onError");
            }

            @Override
            public void onNext(List<Restaurant> restaurants) {
                Timber.d("onNext");
                for (Restaurant restaurant : restaurants) {
                    Timber.d(restaurant.getId() + ": " + restaurant.getName());
                }
            }
        });

我的问题是将这两部分结合起来。我尝试使用flatMap运算符如下：

RxTextView.textChangeEvents(searchEditText)
        .debounce(400, TimeUnit.MILLISECONDS)
        .observeOn(AndroidSchedulers.mainThread())
        .flatMap(new Func1<TextViewTextChangeEvent, Observable<List<Restaurant>>>() {
            @Override
            public Observable<List<Restaurant>> call(TextViewTextChangeEvent txtChangeEvt) {
                return APIManager.getService().searchRestaurants(txtChangeEvt.text().toString());
            }
        })
        .subscribeOn(Schedulers.io())
        .observeOn(AndroidSchedulers.mainThread())
        .subscribe(new Observer<List<Restaurant>>() {
            @Override
            public void onCompleted() {
                Timber.d("onCompleted");
            }

            @Override
            public void onError(Throwable e) {
                Timber.e(e, "onError");
            }

            @Override
            public void onNext(List<Restaurant> restaurants) {
                Timber.d("onNext");
                for (Restaurant restaurant : restaurants) {
                    Timber.d(restaurant.getId() + ": " + restaurant.getName());
                }
            }
        });

当我这样做时，我得到以下异常：

java.lang.IllegalStateException: Must be called from the main thread. Was: Thread[RxCachedThreadScheduler-1,5,main]
                                                                              at com.jakewharton.rxbinding.internal.Preconditions.checkUiThread(Preconditions.java:28)
                                                                              at com.jakewharton.rxbinding.widget.TextViewTextChangeEventOnSubscribe.call(TextViewTextChangeEventOnSubscribe.java:21)
                                                                              at com.jakewharton.rxbinding.widget.TextViewTextChangeEventOnSubscribe.call(TextViewTextChangeEventOnSubscribe.java:12)

所以我尝试通过调用来解决这个问题subscribeOn(AndroidSchedulers.mainThread()但在这种情况下，我当然会收到 NetworkOnMainThread 异常。

那么我该怎么做呢？ 组合应该在不同线程上执行的不同可观察对象的正确方法是什么？

只需删除第一个.observeOn(AndroidSchedulers.mainThread())。看看这个example https://github.com/ReactiveX/RxJava/issues/2925#issuecomment-98649659

Observable.just(1) // 1 will be emited in the IO thread pool
    .subscribeOn(Schedulers.io())
    .flatMap(...) // will be in the IO thread pool
    .observeOn(Schedulers.computation())
    .flatMap(...) // will be executed in the computation thread pool
    .observeOn(AndroidSchedulers.mainThread())
    .subscribe(); // will be executed in the Android main thread (if you're running your code on Android)