[Webflux Tip] 3. Webflux Error 처리!

26 Jul 2019 spring      

Webflux Error 처리!

  • doOnError() : 예외가 발생했을 경우, 특정 행위를 실행시킬 경우 사용
  • onErrorReturn : 예외가 발생했을 때 특정 값을 Return 함
  • onErrorResume : 예외가 발생했을 때 다른 Flux형태로 Return 함
  • onErrorContinue : 예외가 발생했을 때 멈추지 않고 해당 영역만 skip해서 동작함.

doOnError

  • 소스 
    @Test
public void doOnError() {
  Flux.range(0, 5)
      .map(num -> {

          if (num == 3) {
              throw new RuntimeException("Num is " + num);
          }

          return num;
      })
      .doOnError(throwable -> log.error("err : {}", throwable.getMessage()))
      .log()
      .subscribe();
}
  • 결과 
    | onSubscribe([Fuseable] FluxPeekFuseable.PeekFuseableSubscriber)
| request(unbounded)
| onNext(0)
| onNext(1)
| onNext(2)
WebFluxTest3 - err : Num is 3
| onError(java.lang.RuntimeException: Num is 3)
java.lang.RuntimeException: Num is 3

onErrorReturn

  • 소스 
    @Test
public void onErrorReturn() {
  Flux.range(0, 5)
      .map(num -> {

          if (num == 3) {
              throw new RuntimeException("Num is " + num);
          }

          return num;
      })
      .onErrorReturn(100)
      .log()
      .subscribe();
}
  • 결과 
    request(unbounded)
onNext(0)
onNext(1)
onNext(2)
onNext(100)
onComplete()

onErrorResume

  • 소스 
    @Test
public void onErrorResume() {
  Flux.range(0, 5)
      .map(num -> {

          if (num == 3) {
              throw new RuntimeException("Num is " + num);
          }

          return num;
      })
      .onErrorResume(throwable -> {
          log.error("err : {}", throwable.getMessage());
          return Mono.empty();
      })
      .log()
      .subscribe();
}
  • 결과 
    onSubscribe(FluxOnErrorResume.ResumeSubscriber)
request(unbounded)
onNext(0)
onNext(1)
onNext(2)
err : Num is 3
onComplete()

onErrorContinue

  • 소스 
    @Test
public void onErrorContinue() {
  Flux.range(0, 5)
      .map(num -> {

          if (num == 3) {
              throw new RuntimeException("Num is " + num);
          }

          return num;
      })
      .onErrorContinue((error, element) -> log.error("err : {}, element : {} ", error.getMessage(), element))
      .log()
      .subscribe();
}
  • 결과 
    onSubscribe(FluxOnErrorResume.ResumeSubscriber)
request(unbounded)
onNext(0)
onNext(1)
onNext(2)
err : Num is 3
onNext(4)
onComplete()

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