创建一个observate,它在subscribe上生成一个单独的,但是它停止并重用一个特定的值

谢谢你的有趣情节。这里有一个解决方案,我相信可以满足您的需求。它比您的解决方案长,但在涉及多个订阅时应该是安全的。

// subscribe to this observable with one or more subscribers
val requestObservable = replayAndRetry(API.request(), defaultObject)

private fun <T> replayAndRetry(request: Single<T>, defaultValue: T): Observable<T> {
    val responses = BehaviorSubject.create<T>()

    val initialRequest = request
            .onErrorReturnItem(defaultValue)
            .doOnSuccess(responses::onNext)
            .ignoreElement()
            .cache() // run the initial request at most once

    val retryWhenNecessary = Maybe
            .fromCallable { if (responses.value == defaultValue) true else null }
            .flatMapCompletable { request
                    .doOnSuccess(responses::onNext)
                    .ignoreElement()
                    .onErrorComplete() // subject already has the default value
            }
            .toObservable<T>().share() // avoid multiple simultaneous retries

    return responses // source for all responses
            .mergeWith(initialRequest) // will run once and then complete
            .mergeWith(retryWhenNecessary) // will check for default item on every subscription
                                           // will not run simultaneous retries
}