有没有办法取消飞镖的未来？

问题描述：

在Dart UI中，我有一个按钮[submit]来启动长期异步请求。 [submit]处理程序返回一个Future。接下来，按钮[提交]被按钮[取消]取代，以允许取消整个操作。在[cancel]处理程序中，我想取消长操作。如何取消提交处理程序返回的Future？我发现没有办法这样做。

In a Dart UI, I have a button [submit] to launch a long async request. The [submit] handler returns a Future. Next, the button [submit] is replaced by a button [cancel] to allow the cancellation of the whole operation. In the [cancel] handler, I would like to cancel the long operation. How can I cancel the Future returned by the submit handler? I found no method to do that.

答

据我所知，没有办法取消未来。但是有一种取消Stream订阅的方法，也许可以帮助你。

As far as I know, there isn't a way to cancel a Future. But there is a way to cancel a Stream subscription, and maybe that can help you.

在a上调用 onSubmit 按钮返回 StreamSubscription 对象。您可以显式存储该对象，然后调用 cancel（）取消流式订阅：

Calling onSubmit on a button returns a StreamSubscription object. You can explicitly store that object and then call cancel() on it to cancel the stream subscription:

StreamSubscription subscription = someDOMElement.onSubmit.listen((data) {

   // you code here

   if (someCondition == true) {
     subscription.cancel();
   }
});

稍后，作为对某些用户操作的响应，您可以取消订阅：

Later, as a response to some user action, perhaps, you can cancel the subscription:

有没有办法取消飞镖的未来？

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