问题描述
我想知道是否有一个 cache（）运算符可以缓存x个数量的排放，但也会在指定的时间间隔（例如1分钟）后过期。我正在寻找类似的东西......
I was wondering if there was a cache() operator that could cache x number of emissions but also expire them after a specified time interval (e.g. 1 minute). I was looking for something like...
Observable<ImmutableList<MyType>> cachedList = otherObservable
.cache(1, 1, TimeUnit.MINUTES);
这会缓存一个项目，但会在一分钟后过期并清除缓存。
This would cache one item but would expire and clear the cache after a minute.
我做了一些研究，找到了操作员。看起来它可以满足这种需求，但我有一些问题。为什么它很热并且需要连接？这是否与 cache（）运算符不同？我知道 cache（）模仿主题，但不需要连接。
I did some research and found the replay operator. It seemed like it would fulfill this need but I have some questions. Why is it hot and needs to be connected? Does this make it different than the cache() operator? I know the cache() mimics a subject, but it does not require being connected.
推荐答案
缓存和重播适用于不同的用例。缓存是一种自动连接重放 - 通常用于长期重放的所有容器。重放可以有更多的参数化，可以进行有限的时间/大小重放，但需要开发人员指定何时开始。 autoConnect（）运算符允许您将此 ConnectableObservable 实例转换为普通 Observable 一旦订阅者订阅它们就连接到源。通过这种方式，您可以进行有界和自动连接重播（需要RxJava 1.0.14 +）：
cache and replay are meant for different use cases. Cache is an auto-connecting replay-everything container used typically for long-term replays. Replay can have more parametrization and can do bounded time/size replays but requires the developer to specify when to start. The autoConnect() operator lets you turn such ConnectableObservable instances to a plain Observable which connects to the source once a subscriber subscribes to them. This way, you can have a bounded and auto-connecting replay (requires RxJava 1.0.14+):
source.replay(1, TimeUnit.SECONDS).autoConnect().subscribe(...);
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