android - Flowable 的 onErrorResumeNext、networkOnMainThread 出错

Question

我有以下 rxJava 链:

 override fun combineLocationToPlace(req: Flowable<Place>): Flowable<Place> {
        var combinedFlowable = Flowable
                .combineLatest(
                        req,
                        getLastLocation().lastOrError().toFlowable(),
                        BiFunction<Place, Location, Place> { t1, location ->
                            Timber.w("FIRSTINIT - Retrieved location $location")
                            var placeLocation = Location(t1.placeName)
                            placeLocation.latitude = t1.latitude
                            placeLocation.longitude = t1.longitude
                            t1.distance = location.distanceTo(placeLocation)
                            t1
                        })


        return combinedFlowable
                .onErrorResumeNext { t: Throwable ->
                    Timber.w(t, "FIRSTINIT - Could not retrieve location for place (${t.message}) returning original request")
                    req
                }
                .doOnError {
                    Timber.w("FIRSTINIT - did detect the error here...")
                }

        return combinedFlowable
    }

简而言之，我正在从本地数据库(一个地方)中检索一些数据，我想将它与来自 GPS 的最新位置结合起来:

 override fun getLastLocation(requestIfEmpty: Boolean): Observable<Location> {
        var lastLocation = locationProvider.lastKnownLocation
                .doOnNext {
                    Timber.w("Got location $it from last one")
                }
                .doOnComplete {
                    Timber.w("did i get a location?")
                }

        if (requestIfEmpty) {
            Timber.w("Switching to request of location")
            lastLocation = lastLocation.switchIfEmpty(requestLocation())
        }

        return lastLocation.doOnNext {
            Timber.w("Got something!")
            location = it
        }


    }

但我想考虑用户没有最后位置的场景，因此该行:

return combinedFlowable
                    .onErrorResumeNext { t: Throwable ->
                        Timber.w(t, "FIRSTINIT - Could not retrieve location for place (${t.message}) returning original request")
                        req
                    }
                    .doOnError {
                        Timber.w("FIRSTINIT - did detect the error here...")
                    }

它试图捕获任何错误并仅使用原始请求重试，而不将其与任何内容组合。我这样调用这段代码:

fun getPlace(placeId: String) {
        locationManager.combineLocationToPlace(placesRepository.getPlace(placeId))
                .onErrorResumeNext { t: Throwable ->
                    Timber.e(t, "Error resuming next! ")
                    placesRepository.getPlace(placeId)
                }.subscribeOn(schedulerProvider.io()).observeOn(schedulerProvider.ui())
                .subscribeBy(
                        onNext = {
                            place.value = Result.success(it)
                        },
                        onError = {
                            Timber.e("ERROR! $it")
                            place.value = Result.failure(it)
                        }
                )
                .addTo(disposables)

    }

但是，当没有位置时抛出 NoSuchElementException，我的 flowable 切换到原始请求，然后在执行它时我得到一个 NetworkOnMainThread 异常。这个请求不应该在我放在那里的 scheduler.io() 上执行吗(因为我把代码放在那之前)？

如果您想知道，schedulerProvider.io() 转换为:

Schedulers.io()

获取地点:

  /**
     * Retrieves a single place from database
     */
      override fun getPlace(id: String): Flowable<Place> {
        return Flowable.merge(placesDao.getPlace(id),
                refreshPlace(id).toFlowable())
    }

    /**
     * Triggers a refreshPlace update on the db, useful when changing stuff associated with the place
     * itself indirectly (e.g. an experience)
     */
    private fun refreshPlace(id: String): Single<Place> {
        return from(placesApi.getPlace(id))
                .doOnSuccess {
                    placesDao.savePlace(it)
                }
    }

Answer 1

为确保您的网络发生在主线程之外，将其显式发送到后台线程。

使用 Rx 调度程序类中的 IO、新线程或计算调度程序:

subscribeOn(Schedulers.computation())

如果您不想这样做(或者如果您认为它应该已经在后台线程上并且只想调试)，您可以按如下方式记录线程信息:

Thread.currentThread().getName()

当您使用 Schedulers.trampoline() 或者您有不同的观察和订阅调度程序时，这对于跟踪正在发生的事情特别有用，就像您的示例一样:

.subscribeOn(schedulerProvider.io()).observeOn(schedulerProvider.ui())