如何处理Reactive Spring webflux中的错误

Question

由于有很多方法，如onErrorReturn、onErrorResume等，所以哪一个是正确的方法，以处理mono和flux的Reactive Spring webflux中的错误？

Answer 1

分享我的知识：

总共提供了六种处理错误的方法,下面讨论五种：

>

OnErrorReturn:返回整个流的回退值（Mono/Flux）。例如。如果有10个元素的流量，并且元素3发生错误，那么rest 4、5、6…将不会被执行，相反，将考虑回退值。

DoonError：消耗错误并溢出它。停止执行流中的其他元素。

OnErrorMap：将一个错误转换为另一个错误。停止执行流中的其他元素。

所有这五种方法都有三种变体,

null

示例：

1. OnErrorReturn：返回回退值

@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 ));
}

@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 ));
}

@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 ));
}

@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 ));
}

@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 ));
}