在Flot中，当流的值发生变化时，我如何调用Navigator.ush呢？我已经try 了下面的代码，但出现错误.
StreamBuilder(
stream: bloc.streamValue,
builder: (BuildContext context, AsyncSnapshot<int> snapshot) {
if (snapshot.hasData && snapshot.data == 1) {
Navigator.push(
context,
MaterialPageRoute(builder: (context) => SomeNewScreen()),
);
}
return Text("");
});
个
您不应该使用StreamBuilder来处理导航.
StreamBuilder用于构建屏幕的内容，而不是其他内容.
相反，你将不得不听流来手动触发副作用.这是通过使用StatefulWidget和覆盖initState/dispose来实现的:
class Example extends StatefulWidget {
final Stream<int> stream;
const Example({Key key, this.stream}) : super(key: key);
@override
ExampleState createState() => ExampleState();
}
class ExampleState extends State<Example> {
StreamSubscription _streamSubscription;
@override
void initState() {
super.initState();
_listen();
}
@override
void didUpdateWidget(Example oldWidget) {
super.didUpdateWidget(oldWidget);
if (oldWidget.stream != widget.stream) {
_streamSubscription.cancel();
_listen();
}
}
void _listen() {
_streamSubscription = widget.stream.listen((value) {
Navigator.pushNamed(context, '/someRoute/$value');
});
}
@override
void dispose() {
_streamSubscription.cancel();
super.dispose();
}
@override
Widget build(BuildContext context) {
return Container();
}
}
请注意，如果您使用InheritedWidget来获取流(通常是阻塞)，那么您将希望使用didChangeDependencies而不是initState/didUpdateWidget.
这导致:
class Example extends StatefulWidget {
@override
ExampleState createState() => ExampleState();
}
class ExampleState extends State<Example> {
StreamSubscription _streamSubscription;
Stream _previousStream;
void _listen(Stream<int> stream) {
_streamSubscription = stream.listen((value) {
Navigator.pushNamed(context, '/someRoute/$value');
});
}
@override
void didChangeDependencies() {
super.didChangeDependencies();
final bloc = MyBloc.of(context);
if (bloc.stream != _previousStream) {
_streamSubscription?.cancel();
_previousStream = bloc.stream;
_listen(bloc.stream);
}
}
@override
void dispose() {
_streamSubscription.cancel();
super.dispose();
}
@override
Widget build(BuildContext context) {
return Container();
}
}