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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 Flux doOnSubscribe(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 Flux doOnNext(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 Flux doOnError(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 Flux doOnComplete(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 Flux doOnCancel(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 Flux doOnTerminate(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