问题
As per the documentation:
Flux is a stream which can emit 0..N elements:
Flux<String> fl = Flux.just("a", "b", "c");
Mono is a stream of 0..1 elements:
Mono<String> mn = Mono.just("hello");
And as both are the implementations of the Publisher interface in the reactive stream.
Can't we use only Flux in most of the cases as it also can emit 0..1, thus satisfying the conditions of a Mono?
Or there are some specific conditions when only Mono needs to be used and Flux can not handle the operations? Please suggest.
回答1:
In many cases, you are doing some computation or calling a service and you expect exactly one result (or maybe zero or one result), and not a collection that contains possibly multiple results. In such cases, it's more convenient to have a Mono.
Compare it to "regular" Java: you would not use List as the return type of any method that can return zero or one result. You would use Optional instead, which makes it immediately clear that you do not expect more than one result.
回答2:
Flux is equivalent to RxJava Observable is capable of emitting
- zero or more item (streams of many elements)
- and then OPTIONALLY , completing OR failing
Mono can only emit one item at the most (streams one element)
Relations:
- If you concatente two Monos you will get a Flux
- You can call single() on Flux to return a Mono
回答3:
From the docs here
This distinction carries a bit of semantic information into the type, indicating the rough cardinality of the asynchronous processing. For instance, an HTTP request produces only one response, so there is not much sense in doing a count operation. Expressing the result of such an HTTP call as a Mono thus makes more sense than expressing it as a Flux, as it offers only operators that are relevant to a context of zero items or one item.
来源：https://stackoverflow.com/questions/47988433/mono-vs-flux-in-reactive-stream