Question

我正在尝试创建一个Observable，以便它会在一定时间间隔内从网络加载一些数据，并且每当用户刷新页面时。这是我到目前为止的要点：

PublishSubject<Long> refreshSubject = PublishSubject.create();
Observable<MyDataType> observable = Observable.merge(
    Observable.interval(0, 3, TimeUnit.SECONDS),
    refreshSubject
)
.flatMap(t -> {
    // network operations that eventually return a value
    // these operations are not observables themselves
    // they are fully blocking network operations
})
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(data -> {
    // update ui with data
}, error -> {
    // do something with error
});

稍后在刷新回调中我有：

refreshSubject.onNext(0L);

它在间隔很好的情况下运行，但是当我刷新时，它会以NetworkOnMainThreadException爆炸。我以为我是通过subscribeOn / observeOn处理此问题的。我错过了什么？另外，为什么在从间隔触发Observer时这不会导致崩溃？

Answer 1

您必须将subscribeOn(Schedulers.io())更改为observeOn(Schedulers.io())并将其移到flatMap上。原因是您的refreshSubject是一个PublishSubject，它是一个Observable和一个Observer。

由于在结果传递到您的订阅之前，首先在实习生Observable中调用此PublishSubject的onNext()。这也是当你使用Observable时它工作的原因（以及interval默认情况下总是订阅计算线程的事实。）

只需检查这两个片段的输出：

Observable.merge(
    Observable.interval(0, 3, TimeUnit.SECONDS),
    refreshSubject
)
.observeOn(Schedulers.io())
.doOnNext(aLong -> Log.d("Thread", Thread.currentThread().toString()))
.observeOn(AndroidSchedulers.mainThread())
.subscribe(data -> {
    Log.d("Subscribe Thread", Thread.currentThread().toString());
}, error -> {
                // do something with error
            });

VS

Observable.merge(
    Observable.interval(0, 3, TimeUnit.SECONDS),
    refreshSubject
)
.doOnNext(aLong -> Log.d("Thread", Thread.currentThread().toString()))
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(data -> {
    Log.d("Subscribe Thread", Thread.currentThread().toString());
}, error -> {
    // do something with error
});

RxAndroid Observable在意外的线程上运行

1 个答案: