Dart Stream.fromFuture用法及代码示例

从未来创建一个新的single-subscription 流。

当 future 完成时，流将触发一个事件，数据或错误，然后以 done-event 关闭。

例子：

Future<String> futureTask() async {
  await Future.delayed(const Duration(seconds: 5));
  return 'Future complete';
}

final stream = Stream<String>.fromFuture(futureTask());
stream.listen(print,
    onDone: () => print('Done'), onError: print);

// Outputs:
// "Future complete" after 'futureTask' finished.
// "Done" when stream completed.