java - RxJava2 中的 onErrorReturn 仅捕获第一个错误

Question

我在 flowable 中抛出了两个异常，并使用 onErrorReturn 来捕获这些异常。但我发现只捕获了第一个异常。如何捕获所有异常？

Flowable.create(emitter -> {
    emitter.onError(new Exception("error1"));
    emitter.onError(new Exception("error2"));
    }, BackpressureStrategy.MISSING)
        .onErrorReturn(e -> {
            System.out.println("Got error " + e.getMessage());
            return "error";
        })
        .subscribe();

输出:

Got error error1
io.reactivex.exceptions.UndeliverableException: java.lang.Exception: error2
    at io.reactivex.plugins.RxJavaPlugins.onError(RxJavaPlugins.java:349)
    at io.reactivex.internal.operators.flowable.FlowableCreate$BaseEmitter.onError(FlowableCreate.java:271)
    at com.example.springboottest.SimpleApplication.lambda$main$0(SimpleApplication.java:48)
    at io.reactivex.internal.operators.flowable.FlowableCreate.subscribeActual(FlowableCreate.java:72)
    at io.reactivex.Flowable.subscribe(Flowable.java:13094)
    at io.reactivex.internal.operators.flowable.FlowableOnErrorReturn.subscribeActual(FlowableOnErrorReturn.java:33)
    at io.reactivex.Flowable.subscribe(Flowable.java:13094)
    at io.reactivex.Flowable.subscribe(Flowable.java:13030)
    at io.reactivex.Flowable.subscribe(Flowable.java:12890)
    at com.example.springboottest.SimpleApplication.main(SimpleApplication.java:54)
Caused by: java.lang.Exception: error2
    ... 8 more
Exception in thread "main" io.reactivex.exceptions.UndeliverableException: java.lang.Exception: error2
    at io.reactivex.plugins.RxJavaPlugins.onError(RxJavaPlugins.java:349)
    at io.reactivex.internal.operators.flowable.FlowableCreate$BaseEmitter.onError(FlowableCreate.java:271)
    at com.example.springboottest.SimpleApplication.lambda$main$0(SimpleApplication.java:48)
    at io.reactivex.internal.operators.flowable.FlowableCreate.subscribeActual(FlowableCreate.java:72)
    at io.reactivex.Flowable.subscribe(Flowable.java:13094)
    at io.reactivex.internal.operators.flowable.FlowableOnErrorReturn.subscribeActual(FlowableOnErrorReturn.java:33)
    at io.reactivex.Flowable.subscribe(Flowable.java:13094)
    at io.reactivex.Flowable.subscribe(Flowable.java:13030)
    at io.reactivex.Flowable.subscribe(Flowable.java:12890)
    at com.example.springboottest.SimpleApplication.main(SimpleApplication.java:54)
Caused by: java.lang.Exception: error2
    ... 8 more

Answer 1

Observable 在完成或遇到错误后结束。这是契约(Contract)的一部分，没有办法绕过该属性。

处理可观察对象中的“多个”异常的唯一方法是将其像值一样处理，而不是异常。这最终看起来像 Scala's Either construct在实践中。