Project Reactor：为每个订阅的发布者缓存最后一个项目

Question

我有一个处理器，可以订阅在任意时间到达的发布者。对于处理器的每个新订阅者，我想从每个发布者发出最后一个项目。

    class PublishersState {
        val outputProcessor = DirectProcessor.create<String>()

        fun addNewPublisher(publisher: Flux<String>) {
            publisher.subscribe(outputProcessor)
        }

        fun getAllPublishersState(): Flux<String> = outputProcessor
    }

    val publisher1 = Mono
        .just("Item 1 publisher1")
        .mergeWith(Flux.never())

    val publisher2 = Flux
        .just("Item 1 publisher2", "Item 2 publisher2")
        .mergeWith(Flux.never())

    val publishersState = PublishersState()

    publishersState.getAllPublishersState().subscribe {
        println("Subscriber1: $it")
    }

    publishersState.addNewPublisher(publisher1)

    publishersState.addNewPublisher(publisher2)

    publishersState.getAllPublishersState().subscribe {
        println("Subscriber2: $it")
    }

我需要更改上面的代码，因此它将输出以下内容：

Subscriber1: Item 1 publisher1
Subscriber1: Item 1 publisher2
Subscriber1: Item 2 publisher2
// Subscriber2 subscribers here and receives the last item from each publisher
Subscriber2: Item 1 publisher1
Subscriber2: Item 2 publisher2

是否有一种简单的方法来为每个发布者缓存最后一个项目？

Answer 1

使用ReplayProcessor代替DirectProcessor：

val outputProcessor = ReplayProcessor.cacheLast()

Answer 2

我通过以下方式解决了我的情况：

type