ReactiveX 学习笔记（5）合并数据流

Combining Observables

本文的主题为合并 Observable 的操作符。

这里的 Observable 实质上是可观察的数据流。

RxJava操作符（四）Combining

And/Then/When

ReactiveX - And/Then/When operator

Reactive Extensions再入門 その４４「And, Then, Whenメソッド」

And/Then/When 将两个或多个数据流的数据通过 Pattern 和 Plan 中间量合为一体。

And/Then/When 操作符中数据结合的方法为将所有源数据流的第 1 个数据结合，然后再将所有源数据流的第 2 个数据结合，以此类推，直到某一个源数据流没有数据为止。

• RxNET

var one = Observable.Interval(TimeSpan.FromSeconds(1)).Take(5);
var two = Observable.Interval(TimeSpan.FromMilliseconds(250)).Take(10);
var three = Observable.Interval(TimeSpan.FromMilliseconds(150)).Take(14);
var zippedSequence = Observable.When(
    one.And(two)
    .And(three)
    .Then((first, second, third) =>
    new {
        One = first,
        Two = second,
        Three = third
    })
);
zippedSequence.Subscribe(
Console.WriteLine,
() => Console.WriteLine("Completed"));
Console.ReadLine();
/*
{ One = 0, Two = 0, Three = 0 }
{ One = 1, Two = 1, Three = 1 }
{ One = 2, Two = 2, Three = 2 }
{ One = 3, Two = 3, Three = 3 }
{ One = 4, Two = 4, Three = 4 }
Completed
*/

CombineLatest

ReactiveX - CombineLatest operator

Reactive Extensions再入門 その４１「どんどん合成するよ」

CombineLatest 将两个数据流中的最新数据通过调用指定函数合为一体。

• RxNET

var source1 = new Subject<string>();
var source2 = new Subject<int>();
source1
    .CombineLatest(
        source2,
        (l, r) => string.Format("{0}-{1}", l, r))
    .Subscribe(
        s => Console.WriteLine("OnNext: {0}", s),
        () => Console.WriteLine("OnCompleted"));
Console.WriteLine("source1.OnNext(foo)");
source1.OnNext("foo");
Console.WriteLine("source2.OnNext(100)");
source2.OnNext(100);
Console.WriteLine("source2.OnNext(200)");
source2.OnNext(200);
Console.WriteLine("source1.OnNext(bar)");
source1.OnNext("bar");
Console.WriteLine("source1.OnNext(boo)");
source1.OnNext("boo");
Console.WriteLine("source1.OnCompleted()");
source1.OnCompleted();
Console.WriteLine("source2.OnNext(999)");
source2.OnNext(999);
Console.WriteLine("source2.OnCompleted()");
source2.OnCompleted();
/*
source1.OnNext(foo)
source2.OnNext(100)
OnNext: foo-100
source2.OnNext(200)
OnNext: foo-200
source1.OnNext(bar)
OnNext: bar-200
source1.OnNext(boo)
OnNext: boo-200
source1.OnCompleted()
source2.OnNext(999)
OnNext: boo-999
source2.OnCompleted()
OnCompleted
*/

• RxJava

Observables.combineLatest(
    Observable.interval(100, TimeUnit.MILLISECONDS)
        .doOnNext { i -> println("Left emits") },
    Observable.interval(150, TimeUnit.MILLISECONDS)
        .doOnNext { i -> println("Right emits") })
    { i1, i2 -> i1.toString() + " - " + i2 }
    .take(6)
    .dump()
/*
Left emits
Right emits
onNext: 0 - 0
Left emits
onNext: 1 - 0
Left emits
Right emits
onNext: 2 - 0
onNext: 2 - 1
Left emits
onNext: 3 - 1
Right emits
onNext: 3 - 2
onComplete
*/

• RxSwift

let disposeBag = DisposeBag()
let stringSubject = PublishSubject<String>()
let intSubject = PublishSubject<Int>()
Observable.combineLatest(stringSubject, intSubject) { stringElement, intElement in
        "\(stringElement) \(intElement)"
    }
    .subscribe(onNext: { print($0) })
    .disposed(by: disposeBag)
stringSubject.onNext("