Question

下面有一个示例程序可以复制我的问题。

问题：

将flatMap转换应用于某些Observable
订阅前面提到的Observable，将订阅存储在某个地方
在Observable自然终止
在映射器函数返回的Observable中，引发Exception
Flatmap运算符不知道如何处理Exception，引发它，程序崩溃/退出

首选/预期行为：

错误应该传播到我的onError处理程序，而不是在调用RxJavaPlugins#onError时崩溃程序

罪魁祸首是ObservableFlatMap中的代码片段。问题是，一旦处理完父节点，对addThrowable的调用将返回false。因此，错误永远不会传播到onError。

@Override
public void onError(Throwable t) {
  if (parent.errors.addThrowable(t)) {
      if (!parent.delayErrors) {
          parent.disposeAll();
      }
      done = true;
      parent.drain();
  } else {
      RxJavaPlugins.onError(t);
  }
}

在这种情况下我该怎么办？我需要一个像flatMap一样的运算符，并将错误传播到我的onError处理程序而不是崩溃我的程序。

这是我的Android应用程序的真实场景。当用户退出窗口/活动时，将自动处理订阅，并且由于InterruptedIOException s而在处理后可能会引发异常。

复制问题的代码

import io.reactivex.Observable;
import io.reactivex.disposables.Disposable;
import io.reactivex.plugins.RxJavaPlugins;
import io.reactivex.schedulers.Schedulers;

public class Main {

  public static void main(String[] args) throws InterruptedException {
    RxJavaPlugins.setErrorHandler((throwable)->{
      System.out.println("Please don't come through here");
      throwable.printStackTrace();
    });
    Disposable disposable = Observable.just(1)
        .subscribeOn(Schedulers.computation())
        .flatMap((item)->{
          return Observable.just(1)
              .doOnNext((arg)->Thread.sleep(1000))
              .doOnNext((arg)->{
                throw new RuntimeException("Error");
              });
        })
        .subscribe(System.out::println, (throwable)->{
          System.out.println("Please come through here");
          throwable.printStackTrace();
        });
    Thread.sleep(500);
    disposable.dispose();
    Thread.sleep(1000);
  }

}

执行输出

Please don't come through here
io.reactivex.exceptions.UndeliverableException: java.lang.InterruptedException: sleep interrupted
  at io.reactivex.plugins.RxJavaPlugins.onError(RxJavaPlugins.java:349)
  at io.reactivex.internal.operators.observable.ObservableFlatMap$InnerObserver.onError(ObservableFlatMap.java:573)
  at io.reactivex.internal.operators.observable.ObservableDoOnEach$DoOnEachObserver.onError(ObservableDoOnEach.java:119)
  at io.reactivex.internal.operators.observable.ObservableDoOnEach$DoOnEachObserver.onError(ObservableDoOnEach.java:119)
  at io.reactivex.internal.operators.observable.ObservableDoOnEach$DoOnEachObserver.onNext(ObservableDoOnEach.java:99)
  at io.reactivex.internal.operators.observable.ObservableScalarXMap$ScalarDisposable.run(ObservableScalarXMap.java:248)
  at io.reactivex.internal.operators.observable.ObservableJust.subscribeActual(ObservableJust.java:35)
  at io.reactivex.Observable.subscribe(Observable.java:10903)
  at io.reactivex.internal.operators.observable.ObservableDoOnEach.subscribeActual(ObservableDoOnEach.java:42)
  at io.reactivex.Observable.subscribe(Observable.java:10903)
  at io.reactivex.internal.operators.observable.ObservableDoOnEach.subscribeActual(ObservableDoOnEach.java:42)
  at io.reactivex.Observable.subscribe(Observable.java:10903)
  at io.reactivex.internal.operators.observable.ObservableFlatMap$MergeObserver.subscribeInner(ObservableFlatMap.java:162)
  at io.reactivex.internal.operators.observable.ObservableFlatMap$MergeObserver.onNext(ObservableFlatMap.java:139)
  at io.reactivex.internal.operators.observable.ObservableSubscribeOn$SubscribeOnObserver.onNext(ObservableSubscribeOn.java:58)
  at io.reactivex.internal.operators.observable.ObservableScalarXMap$ScalarDisposable.run(ObservableScalarXMap.java:248)
  at io.reactivex.internal.operators.observable.ObservableJust.subscribeActual(ObservableJust.java:35)
  at io.reactivex.Observable.subscribe(Observable.java:10903)
  at io.reactivex.internal.operators.observable.ObservableSubscribeOn$SubscribeTask.run(ObservableSubscribeOn.java:96)
  at io.reactivex.internal.schedulers.ScheduledDirectTask.call(ScheduledDirectTask.java:38)
  at io.reactivex.internal.schedulers.ScheduledDirectTask.call(ScheduledDirectTask.java:26)
  at java.util.concurrent.FutureTask.run(FutureTask.java:266)
  at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180)
  at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293)
  at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
  at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
  at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.InterruptedException: sleep interrupted
  at java.lang.Thread.sleep(Native Method)
  at Main.lambda$null$1(Main.java:18)
  at io.reactivex.internal.operators.observable.ObservableDoOnEach$DoOnEachObserver.onNext(ObservableDoOnEach.java:95)
  ... 22 more

预期/首选输出

Please come through here
java.lang.RuntimeException: Error
  at Main.lambda$null$2(Main.java:19)
  at io.reactivex.internal.operators.observable.ObservableDoOnEach$DoOnEachObserver.onNext(ObservableDoOnEach.java:95)
  at io.reactivex.internal.operators.observable.ObservableDoOnEach$DoOnEachObserver.onNext(ObservableDoOnEach.java:103)
  at io.reactivex.internal.operators.observable.ObservableScalarXMap$ScalarDisposable.run(ObservableScalarXMap.java:248)
  at io.reactivex.internal.operators.observable.ObservableJust.subscribeActual(ObservableJust.java:35)
  at io.reactivex.Observable.subscribe(Observable.java:10903)
  at io.reactivex.internal.operators.observable.ObservableDoOnEach.subscribeActual(ObservableDoOnEach.java:42)
  at io.reactivex.Observable.subscribe(Observable.java:10903)
  at io.reactivex.internal.operators.observable.ObservableDoOnEach.subscribeActual(ObservableDoOnEach.java:42)
  at io.reactivex.Observable.subscribe(Observable.java:10903)
  at io.reactivex.internal.operators.observable.ObservableFlatMap$MergeObserver.subscribeInner(ObservableFlatMap.java:162)
  at io.reactivex.internal.operators.observable.ObservableFlatMap$MergeObserver.onNext(ObservableFlatMap.java:139)
  at io.reactivex.internal.operators.observable.ObservableSubscribeOn$SubscribeOnObserver.onNext(ObservableSubscribeOn.java:58)
  at io.reactivex.internal.operators.observable.ObservableScalarXMap$ScalarDisposable.run(ObservableScalarXMap.java:248)
  at io.reactivex.internal.operators.observable.ObservableJust.subscribeActual(ObservableJust.java:35)
  at io.reactivex.Observable.subscribe(Observable.java:10903)
  at io.reactivex.internal.operators.observable.ObservableSubscribeOn$SubscribeTask.run(ObservableSubscribeOn.java:96)
  at io.reactivex.internal.schedulers.ScheduledDirectTask.call(ScheduledDirectTask.java:38)
  at io.reactivex.internal.schedulers.ScheduledDirectTask.call(ScheduledDirectTask.java:26)
  at java.util.concurrent.FutureTask.run(FutureTask.java:266)
  at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180)
  at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293)
  at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
  at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
  at java.lang.Thread.run(Thread.java:748)

Answer 1

问题出在.subscribeOn(Schedulers.computation())之前的flatMap。当你dispose中断线程产生平面地图可观察数据时会破坏整个订阅。要解决这个问题，你应该在flatMap之后或之内指定订阅，或者在另一个帖子中观察它。

工作示例：

RxJavaPlugins.setErrorHandler((throwable) -> {
        System.out.println("Please don't come through here");
        throwable.printStackTrace();
    });
    Disposable disposable = Observable.just(1)
            .flatMap((item) -> {
                return Observable.just(1)

                        .doOnNext((arg) -> Thread.sleep(1000))
                        .doOnNext((arg) -> {
                            throw new IllegalStateException("Error");
                        })
                        .subscribeOn(Schedulers.computation());
            })
            .subscribe(System.out::println,
                    (throwable) -> {
                        System.out.println("Please come through here");
                        throwable.printStackTrace();
                    });
    Thread.sleep(500);
    disposable.dispose();
    Thread.sleep(1000);

使用Observable.flatMap时的错误处理

1 个答案: