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本文主要研究一下reactive streams Publisher的doOn方法
doOn系列方法
这里以Flux为例
reactor-core-3.1.2.RELEASE-sources.jar!/reactor/core/publisher/Flux.java
doOnSubscribe
/** * Add behavior (side-effect) triggered when the {@link Flux} is subscribed. **
*
* @param onSubscribe the callback to call on {@link Subscriber#onSubscribe} * * @return an observed {@link Flux} */ public final FluxdoOnSubscribe(Consumer onSubscribe) { Objects.requireNonNull(onSubscribe, "onSubscribe"); return doOnSignal(this, onSubscribe, null, null, null, null, null, null); }
doOnRequest
/** * Add behavior (side-effect) triggering a {@link LongConsumer} when this {@link Flux} * receives any request. ** Note that non fatal error raised in the callback will not be propagated and * will simply trigger {@link Operators#onOperatorError(Throwable, Context)}. * *
** * @param consumer the consumer to invoke on each request * * @return an observed {@link Flux} */ public final Flux
doOnRequest(LongConsumer consumer) { Objects.requireNonNull(consumer, "consumer"); return doOnSignal(this, null, null, null, null, null, consumer, null); }
doOnNext
/** * Add behavior (side-effect) triggered when the {@link Flux} emits an item. **
*
* @param onNext the callback to call on {@link Subscriber#onNext} * * @return an observed {@link Flux} */ public final FluxdoOnNext(Consumer onNext) { Objects.requireNonNull(onNext, "onNext"); return doOnSignal(this, null, onNext, null, null, null, null, null); }
doOnError
/** * Add behavior (side-effect) triggered when the {@link Flux} completes with an error. **
*
* @param onError the callback to call on {@link Subscriber#onError} * * @return an observed {@link Flux} */ public final FluxdoOnError(Consumer onError) { Objects.requireNonNull(onError, "onError"); return doOnSignal(this, null, null, onError, null, null, null, null); }
doOnEach
/**
* Add behavior (side-effects) triggered when the {@link Flux} emits an item, fails with an error
* or completes successfully. All these events are represented as a {@link Signal}
* that is passed to the side-effect callback. Note that this is an advanced operator,
* typically used for monitoring of a Flux.
*
* @param signalConsumer the mandatory callback to call on
* {@link Subscriber#onNext(Object)}, {@link Subscriber#onError(Throwable)} and
* {@link Subscriber#onComplete()}
* @return an observed {@link Flux}
* @see #doOnNext(Consumer)
* @see #doOnError(Consumer)
* @see #doOnComplete(Runnable)
* @see #materialize()
* @see Signal
*/
public final Flux doOnEach(Consumer> signalConsumer) {
return onAssembly(new FluxDoOnEach<>(this, signalConsumer));
} doOnComplete
/** * Add behavior (side-effect) triggered when the {@link Flux} completes successfully. **
*
* @param onComplete the callback to call on {@link Subscriber#onComplete} * * @return an observed {@link Flux} */ public final FluxdoOnComplete(Runnable onComplete) { Objects.requireNonNull(onComplete, "onComplete"); return doOnSignal(this, null, null, null, onComplete, null, null, null); }
doOnCancel
/** * Add behavior (side-effect) triggered when the {@link Flux} is cancelled. **
*
* @param onCancel the callback to call on {@link Subscription#cancel} * * @return an observed {@link Flux} */ public final FluxdoOnCancel(Runnable onCancel) { Objects.requireNonNull(onCancel, "onCancel"); return doOnSignal(this, null, null, null, null, null, null, onCancel); }
doOnTerminate
/** * Add behavior (side-effect) triggered when the {@link Flux} terminates, either by * completing successfully or with an error. **
*
* @param onTerminate the callback to call on {@link Subscriber#onComplete} or {@link Subscriber#onError} * * @return an observed {@link Flux} */ public final FluxdoOnTerminate(Runnable onTerminate) { Objects.requireNonNull(onTerminate, "onTerminate"); return doOnSignal(this, null, null, e -> onTerminate.run(), onTerminate, null, null, null); }
doOnSignal
@SuppressWarnings("unchecked")
static Flux doOnSignal(Flux source,
@Nullable Consumer onSubscribe,
@Nullable Consumer onNext,
@Nullable Consumer onError,
@Nullable Runnable onComplete,
@Nullable Runnable onAfterTerminate,
@Nullable LongConsumer onRequest,
@Nullable Runnable onCancel) {
if (source instanceof Fuseable) {
return onAssembly(new FluxPeekFuseable<>(source,
onSubscribe,
onNext,
onError,
onComplete,
onAfterTerminate,
onRequest,
onCancel));
}
return onAssembly(new FluxPeek<>(source,
onSubscribe,
onNext,
onError,
onComplete,
onAfterTerminate,
onRequest,
onCancel));
} 实例
static class DemoSubsriber implements Subscriber{
static final Logger LOGGER = LoggerFactory.getLogger(DemoSubsriber.class);
@Override
public void onSubscribe(Subscription s) {
LOGGER.info("request max");
s.request(Integer.MAX_VALUE);
}
@Override
public void onNext(Integer integer) {
LOGGER.info("get data:{}",integer);
}
@Override
public void onError(Throwable t) {
}
@Override
public void onComplete() {
LOGGER.info("onComplete");
}
}
@Test
public void testDoOnMethods(){
Flux.range(1, 3)
// .log()
.doOnSubscribe(e -> LOGGER.info("doOnSubscribe:{}",e))
.doOnEach(e -> LOGGER.info("doOnEach:{}",e))
.doOnError(e -> LOGGER.info("doOnError:{}",e))
.doOnNext(e -> LOGGER.info("doOnNext:{}",e))
.doOnRequest(e -> LOGGER.info("doOnRequest:{}",e))
.doOnTerminate(new Runnable() {
@Override
public void run() {
LOGGER.info("doOnTerminate");
}
})
.doOnCancel(new Runnable() {
@Override
public void run() {
LOGGER.info("doOnCancel");
}
})
.doOnComplete(new Runnable() {
@Override
public void run() {
LOGGER.info("doOnComplete");
}
})
.subscribe(new DemoSubsriber());
} 输出
23:14:16.837 [main] DEBUG reactor.util.Loggers$LoggerFactory - Using Slf4j logging framework
23:14:16.850 [main] INFO com.example.demo.FluxTest - doOnSubscribe:reactor.core.publisher.FluxRange$RangeSubscription@20398b7c
23:14:16.852 [main] INFO com.example.demo.FluxTest$DemoSubsriber - request max
23:14:16.852 [main] INFO com.example.demo.FluxTest - doOnRequest:2147483647
23:14:16.852 [main] INFO com.example.demo.FluxTest - doOnEach:reactor.core.publisher.FluxDoOnEach$DoOnEachSubscriber@2286778
23:14:16.852 [main] INFO com.example.demo.FluxTest - doOnNext:1
23:14:16.852 [main] INFO com.example.demo.FluxTest$DemoSubsriber - get data:1
23:14:16.852 [main] INFO com.example.demo.FluxTest - doOnEach:reactor.core.publisher.FluxDoOnEach$DoOnEachSubscriber@2286778
23:14:16.852 [main] INFO com.example.demo.FluxTest - doOnNext:2
23:14:16.852 [main] INFO com.example.demo.FluxTest$DemoSubsriber - get data:2
23:14:16.852 [main] INFO com.example.demo.FluxTest - doOnEach:reactor.core.publisher.FluxDoOnEach$DoOnEachSubscriber@2286778
23:14:16.852 [main] INFO com.example.demo.FluxTest - doOnNext:3
23:14:16.852 [main] INFO com.example.demo.FluxTest$DemoSubsriber - get data:3
23:14:16.853 [main] INFO com.example.demo.FluxTest - doOnEach:onComplete()
23:14:16.853 [main] INFO com.example.demo.FluxTest - doOnTerminate
23:14:16.853 [main] INFO com.example.demo.FluxTest - doOnComplete
23:14:16.856 [main] INFO com.example.demo.FluxTest$DemoSubsriber - onComplete小结
doOn系列方法是publisher的同步钩子方法，在subscriber触发一系列事件的时候触发。
doc
- flux