Question

在以下代码中，在完成unSubscribe之后，如何以及在何处明确Observable明确取消订阅onComplete。

getObservable()
    .observeOn(AndroidSchedulers.mainThread())
    .subscribeOn(Schedulers.io())
    .subscribe(new Subscriber<Boolean>() {
        @Override
        public void onCompleted() {
            doSomething();
        }

        @Override
        public void onError(Throwable e) {
            thereIsError();
        }

        @Override
        public void onNext(Boolean status) {
            updateView();
        }
    });

Answer 1

您可以保存Disposable方法返回的subscribe并在onCompleted回调

中使用它

Disposable d = 
getObservable()
    .observeOn(AndroidSchedulers.mainThread())
    .subscribeOn(Schedulers.io())
    .subscribe(new Subscriber<Boolean>() {
        @Override
        public void onCompleted() {
            doSomething();
            d.dispose();
        }

        @Override
        public void onError(Throwable e) {
            thereIsError();
        }

        @Override
        public void onNext(Boolean status) {
            updateView();
        }
    });

Answer 2

 disposables.add(sampleObservable()
            // Run on a background thread
            .subscribeOn(Schedulers.io())
            // Be notified on the main thread
            .observeOn(AndroidSchedulers.mainThread())
            .subscribeWith(new DisposableObserver<String>() {
                @Override
                public void onComplete() {
                    // Do some work for completion
                }

                @Override
                public void onError(Throwable e) {
                     // Do some work for error
                }

                @Override
                public void onNext(String value) {
                    // Do some work for next
                }
            }));

明确并取消订阅

@Override
protected void onDestroy() {
    super.onDestroy();
    disposables.clear(); // do not send event after activity has been destroyed
    disposables.dispose();
}

Answer 3

简短的回答是，您没有理由明确取消订阅，因为观察链已经完成了取消订阅。您可以通过添加此运算符来自行测试：

.doOnUnsubscribe( () -> System.out.println("Unsubscribed") )

Answer 4

如果要立即取消订阅，只需使用take（1）。在调用take（1）之后，应该使onComplete被调用。

Disposable d = 
getObservable()
    .observeOn(AndroidSchedulers.mainThread())
    .subscribeOn(Schedulers.io())
    .take(1)//take the first, then stop emissions
    .subscribe(new Subscriber<Boolean>() {
        @Override
        public void onCompleted() {
            doSomething();
            d.dispose();
        }

        @Override
        public void onError(Throwable e) {
            thereIsError();
        }

        @Override
        public void onNext(Boolean status) {
            updateView();
        }
    });

如何在onComplete之后显式取消订阅observable

4 个答案: