翻譯自：https://tech.io/playgrounds/929/reactive-programming-with-reactor-3/OthersOperations
Other Operations
Description
In this section, we'll have a look at a few more useful operators that don't
fall into the broad categories we explored earlier. Reactor 3 contains a lot
of operators, so don't hesitate to have a look at the
Flux
and Mono
javadocs as well as the reference guide
to learn about more of them.
在本節(jié)中投慈，我們將了解一些更有用的運(yùn)算符尉辑，這些運(yùn)算符不屬于我們前面探討的大類(lèi)別铡俐。
Reactor 3包含很多運(yùn)算符赠幕，所以請(qǐng)毫不猶豫地查看Flux和Mono javadocs以及參考指南蚀之，以了解更多袱院。
Practice
In the first exercise we'll receive 3 Flux<String>. Their elements could
arrive with latency, yet each time the three sequences have all emitted
an element, we want to combine these 3 elements and create a new User.
This concatenate-and-transform operation is called zip:
在第一個(gè)練習(xí)中嘁字，我們將收到3個(gè)Flux<String>蒿往。它們的元素可能會(huì)延遲到達(dá)，但每次這三個(gè)序列
都發(fā)出一個(gè)元素棕诵，我們希望將這三個(gè)元素結(jié)合起來(lái)裁良，創(chuàng)建一個(gè)新用戶。這種連接和轉(zhuǎn)換操作稱為zip：
// Create a Flux of user from Flux of username, firstname and lastname.
Flux<User> userFluxFromStringFlux(Flux<String> usernameFlux, Flux<String> firstnameFlux, Flux<String> lastnameFlux) {
return Flux.zip(usernameFlux, firstnameFlux, lastnameFlux).map(tuples->new User(tuples.getT1(), tuples.getT2(), tuples.getT3()));
}
If you have 3 possible Mono sources and you only want to keep the one that
emits its value the fastest, you can use the firstWithValue static method:
如果您有3個(gè)可能的Mono源校套，并且只想保持發(fā)射其值最快的一個(gè)价脾，那么可以使用firstWithValue靜態(tài)方法：
// Return the mono which returns its value faster
Mono<User> useFastestMono(Mono<User> mono1, Mono<User> mono2) {
return Mono.firstWithValue(mono1, mono2);
}
Flux also has the firstWithValue static method. Only the first element
emitted by each Flux is considered to select the fastest Flux (which is
then mirrored in the output):
Flux也有firstWithValue靜態(tài)方法。只考慮每個(gè)通量發(fā)射的第一個(gè)元素來(lái)選擇最快的通量（然后在輸出中鏡像）：
// Return the flux which returns the first value faster
Flux<User> useFastestFlux(Flux<User> flux1, Flux<User> flux2) {
return Flux.firstWithValue(flux1, flux2);
}
Sometimes you're not interested in elements of a Flux<T>. If you want to
still keep a Flux<T> type, you can use ignoreElements(). But if you really
just want the completion, represented as a Mono<Void>, you can use then() instead:
有時(shí)你對(duì)Flux<T>的元素不感興趣笛匙。如果仍要保持Flux<T>類(lèi)型侨把，可以使用ignoreElements()。
但是妹孙，如果您真的只想完成秋柄，用Mono<Void>表示，您可以使用then()：
// Convert the input Flux<User> to a Mono<Void> that represents the complete signal of the flux
Mono<Void> fluxCompletion(Flux<User> flux) {
return flux.then();
}
Reactive Streams does not allow null values in onNext. There's an operator
that allow to just emit one value, unless it is null in which case it will
revert to an empty Mono. Can you find it?
反應(yīng)流不允許onNext中出現(xiàn)空值蠢正。有一個(gè)運(yùn)算符只允許發(fā)出一個(gè)值骇笔，除非它為null，在這種情況下嚣崭，
它將恢復(fù)為空的Mono笨触。你能找到它嗎？
// Return a valid Mono of user for null input and non null input user (hint: Reactive Streams do not accept null values)
Mono<User> nullAwareUserToMono(User user) {
return Mono.justOrEmpty(user);
}
Similarly, if you want to prevent the empty Mono case by falling back to a
different one, you can find an operator that does this switch:
類(lèi)似地雹舀，如果您想通過(guò)返回另一個(gè)Mono來(lái)防止出現(xiàn)空Mono情況芦劣，您可以找到一個(gè)執(zhí)行此switch的運(yùn)算符：
// Return the same mono passed as input parameter, expect that it will emit User.SKYLER when empty
Mono<User> emptyToSkyler(Mono<User> mono) {
//這兩個(gè)api都可以實(shí)現(xiàn)
return mono.defaultIfEmpty(User.SKYLER);
//return mono.switchIfEmpty(Mono.just(User.SKYLER));
}
Sometimes you want to capture all values emitted by Flux into separate List.
In this case you can use collectList operator that would return Mono
containing that List.
有時(shí)，您希望將Flux發(fā)出的所有值捕獲到單獨(dú)的List中说榆。在這種情況下虚吟，
您可以使用collectList運(yùn)算符返回包含該List的Mono。
// Convert the input Flux<User> to a Mono<List<User>> containing list of collected flux values
Mono<List<User>> fluxCollection(Flux<User> flux) {
return flux.collectList();
}
There are more operators belonging to the collect family. You can check them
out in Flux documentation.
有更多的運(yùn)算符屬于collect系列签财。您可以在Flux文檔中查看它們稍味。
