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Sharing my knowledge: In total there are six methods provided to handle error, five discussed below: onErrorReturn: return fallback value for entire stream (mono/flux). E.g. if there’s a flux of 10 elements, and error happens on element 3, then rest 4,5,6… won’t be executed, instead the fallback value will be considered. onErrorResume: return fallback value in terms on Mono/Flux for entire stream (mono/flux). E.g. if there’s a flux of 10 elements, and error happens on element 3, then rest 4,5,6… won’t be executed, instead the fallback value will be considered. onErrorContinue: consumes (error,data) and does NOT split it over. It considers the consumer for the error elements, and leave the downstream chain as it for good elements. E.g. if there’s a flux of 10 elements, and error happens on element 3, then all elements (1 to 10) except 3 will have normal execution, but element 3 will have a different execution as mentioned in the consumer of onErrorContinue doOnError: consumes error and spills it over. Stops execution for further elements in stream. onErrorMap: cast one error into another. Stops execution for further elements in stream. All these five methods come in 3 variants, Simple: consider directly the expected argument With Exception: consider the expected argument, if the exception matches the exception class provided With Predicate: consider the expected argument, if the predicate yields true Examples: onErrorReturn: return fallback value @Test public void onErrorReturnDirectly_Mono() { Mono.just(2) .map(i -> i/0) // will produce ArithmeticException .onErrorReturn(4) .subscribe(num -> log.info("Number: {}", num )); } @Test public void onErrorReturnIfArithmeticException_Mono() { Mono.just(2) .map(i -> i/0) // will produce ArithmeticException .onErrorReturn(ArithmeticException.class, 4) .subscribe(num -> log.info("Number: {}", num )); } @Test public void onErrorReturnIfPredicatePasses_Mono() { Mono.just(2) .map(i -> i/0) // will produce ArithmeticException .onErrorReturn(error -> error instanceof ArithmeticException, 4) .subscribe(num -> log.info("Number: {}", num )); }onErrorResume: return fallback value in terms on Mono/Flux @Test public void onErrorResume_Mono() { Mono.just(2) .map(i -> i/0) // will produce ArithmeticException .onErrorResume(error -> Mono.just(4)) .subscribe(num -> log.info("Number: {}", num )); } @Test public void onErrorResumeIfArithmeticException_Mono() { Mono.just(2) .map(i -> i/0) // will produce ArithmeticException .onErrorResume( ArithmeticException.class, error -> Mono.just(4) ) .subscribe(num -> log.info("Number: {}", num )); } @Test public void onErrorResumeIfPredicatePasses_Mono() { Mono.just(2) .map(i -> i/0) // will produce ArithmeticException .onErrorResume( error -> error instanceof ArithmeticException, error -> Mono.just(4) ) .subscribe(num -> log.info("Number: {}", num )); }onErrorContinue: consumes (error,data) and does NOT split it over. @Test public void onErrorContinue_Mono() { Mono.just(2) .map(i -> i/0) // will produce ArithmeticException .onErrorContinue((error, obj) -> log.info("error:[{}], obj:[{}]", error, obj )) .subscribe(num -> log.info("Number: {}", num )); } @Test public void onErrorContinueIfArithmeticException_Mono() { Mono.just(2) .map(i -> i/0) // will produce ArithmeticException .onErrorContinue( ArithmeticException.class, (error, obj) -> log.info("error:[{}], obj:[{}]", error, obj ) ) .subscribe(num -> log.info("Number: {}", num )); } @Test public void onErrorContinueIfPredicatePasses_Mono() { Mono.just(2) .map(i -> i/0) // will produce ArithmeticException .onErrorContinue( error -> error instanceof ArithmeticException, (error, obj) -> log.info("error:[{}], obj:[{}]", error, obj ) ) .subscribe(num -> log.info("Number: {}", num )); }doOnError: consumes error and spills it over @Test public void doOnError_Mono() { Mono.just(2) .map(i -> i/0) // will produce ArithmeticException .doOnError(error -> log.info("caught error")) .subscribe(num -> log.info("Number: {}", num )); } @Test public void doOnErrorIfArithmeticException_Mono() { Mono.just(2) .map(i -> i/0) // will produce ArithmeticException .doOnError( ArithmeticException.class, error -> log.info("caught error") ) .subscribe(num -> log.info("Number: {}", num )); } @Test public void doOnErrorIfPredicatePasses_Mono() { Mono.just(2) .map(i -> i/0) // will produce ArithmeticException .doOnError( error -> error instanceof ArithmeticException, error -> log.info("caught error") ) .subscribe(num -> log.info("Number: {}", num )); }onErrorMap: cast one error into another @Test public void OnErrorMap_Mono() { Mono.just(2) .map(i -> i/0) // will produce ArithmeticException .onErrorMap(error -> new RuntimeException("SomeMathException")) .subscribe(num -> log.info("Number: {}", num )); } @Test public void OnErrorMapIfArithmeticException_Mono() { Mono.just(2) .map(i -> i/0) // will produce ArithmeticException .onErrorMap( ArithmeticException.class, error -> new RuntimeException("SomeMathException") ) .subscribe(num -> log.info("Number: {}", num )); } @Test public void OnErrorMapIfPredicatePasses_Mono() { Mono.just(2) .map(i -> i/0) // will produce ArithmeticException .onErrorMap( error -> error instanceof ArithmeticException, error -> new RuntimeException("SomeMathException") ) .subscribe(num -> log.info("Number: {}", num )); } (责任编辑：) |