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本文主要研究下Flux的compose與flatMap操作
compose
Flux.just("1", "2","3")
.log()
.compose(stringFlux -> {
LOGGER.info("compose executed");
return stringFlux.map(e -> e + "$");
}).subscribe(LOGGER::info);輸出如下：
20:59:15.692 [main] DEBUG reactor.util.Loggers$LoggerFactory - Using Slf4j logging framework
20:59:15.702 [main] INFO com.example.demo.FluxTest - compose executed
20:59:15.707 [main] INFO reactor.Flux.Array.1 - | onSubscribe([Synchronous Fuseable] FluxArray.ArraySubscription)
20:59:15.709 [main] INFO reactor.Flux.Array.1 - | request(unbounded)
20:59:15.709 [main] INFO reactor.Flux.Array.1 - | onNext(1)
20:59:15.709 [main] INFO com.example.demo.FluxTest - 1$
20:59:15.710 [main] INFO reactor.Flux.Array.1 - | onNext(2)
20:59:15.710 [main] INFO com.example.demo.FluxTest - 2$
20:59:15.710 [main] INFO reactor.Flux.Array.1 - | onNext(3)
20:59:15.710 [main] INFO com.example.demo.FluxTest - 3$
20:59:15.710 [main] INFO reactor.Flux.Array.1 - | onComplete()可以看到compose executed只列印一次
flatMap
Flux.just("1","2","3")
.log()
.flatMap(s -> {
LOGGER.info("flatMap executed");
return Flux.just(s+"$");
}).subscribe(LOGGER::info);輸出如下：
21:00:54.497 [main] DEBUG reactor.util.Loggers$LoggerFactory - Using Slf4j logging framework
21:00:54.516 [main] INFO reactor.Flux.Array.1 - | onSubscribe([Synchronous Fuseable] FluxArray.ArraySubscription)
21:00:54.519 [main] INFO reactor.Flux.Array.1 - | request(256)
21:00:54.520 [main] INFO reactor.Flux.Array.1 - | onNext(1)
21:00:54.520 [main] INFO com.example.demo.FluxTest - flatMap executed
21:00:54.520 [main] INFO com.example.demo.FluxTest - 1$
21:00:54.520 [main] INFO reactor.Flux.Array.1 - | onNext(2)
21:00:54.520 [main] INFO com.example.demo.FluxTest - flatMap executed
21:00:54.520 [main] INFO com.example.demo.FluxTest - 2$
21:00:54.520 [main] INFO reactor.Flux.Array.1 - | onNext(3)
21:00:54.520 [main] INFO com.example.demo.FluxTest - flatMap executed
21:00:54.520 [main] INFO com.example.demo.FluxTest - 3$
21:00:54.521 [main] INFO reactor.Flux.Array.1 - | onComplete()可以看到flatMap executed在每次onNext的時候都列印一次
小結
compose操作是將整個flux作為一個整體輸入一次性轉換，而flatMap是針對flux的每個item作為輸入來進行轉換。