我是 Flutter 新手,我使用 streambuilder 实现了 bloc 架构。 我创建了 2 个页面,只有一个按钮可以改变我的背景颜色。所有这些页面都在监听流以更改背景颜色,但是当我在第一页上更改时,它不会在第二页上更改。 但是如果有 1 页决定更改它,我希望我的所有应用程序都更改
我是否需要初始化一个我的 2 个屏幕使用它的单例块?因为目前每个屏幕都初始化了自己的块 这是1页的例子(第二页是一样的)
class Test extends StatelessWidget {
final ColorBloc _bloc = ColorBloc();
@override
Widget build(BuildContext context) {
return StreamBuilder<Response<ColorResponse>>(
stream: _bloc.stream,
builder: (context, snapshot) {
if (snapshot.hasData) {
return Scaffold(
appBar: AppBar(
title: Text('First Route clicked'),
),
backgroundColor: snapshot.data.data.color,
body: new Center(
child: new InkWell(
onTap: () {
Navigator.push(
context,
MaterialPageRoute(builder: (context) => Act2()),
);
}, // Handle your callback
child: Ink(height: 100, width: 100, color: Colors.blue),
)),
floatingActionButton: FloatingActionButton(
onPressed: () {
_bloc.changeColor(Colors.yellow);
},
child: Icon(Icons.navigation),
backgroundColor: Colors.green,
));
}
return Scaffold(
appBar: AppBar(
title: Text('First Route'),
),
body: Center(
child: new InkWell(
onTap: () {
Navigator.push(
context,
MaterialPageRoute(builder: (context) => Act2()),
);
}, // Handle your callback
child: Ink(height: 200, width: 200, color: Colors.red))),
floatingActionButton: FloatingActionButton(
onPressed: () {
_bloc.changeColor(Colors.yellow);
},
child: Icon(Icons.navigation),
backgroundColor: Colors.green,
));
},
);
}
}
答案 0 :(得分:0)
要在 bloc 触发事件时更改所有屏幕的状态,您可以使用多个 StreamBuilder,但它们都需要监听触发事件的 bloc。您可以尝试以下两种方式:
class Test extends StatelessWidget {
final ColorBloc _bloc = ColorBloc();
@override
Widget build(BuildContext context) {
return StreamBuilder<Response<ColorResponse>>(
// ... other lines
body: new Center(
child: new InkWell(
onTap: () {
// Pass your bloc to the 2nd screen
Navigator.push(
context,
MaterialPageRoute(builder: (context) => Act2(bloc: _bloc)),
);
},
// ... other lines
class Test extends StatelessWidget {
final ColorBloc _bloc = ColorBloc();
@override
Widget build(BuildContext context) {
// Use Provider to provide the bloc down the widget tree
return Provider(
create: (_) => _bloc,
child: StreamBuilder<Response<ColorResponse>>(
// ... other lines
然后在第二个屏幕(我假设是 Act2())中,您从提供者那里获得 ColorBloc:
class Act2 extends StatefulWidget {
@override
_Act2State createState() => _Act2State();
}
class _Act2State extends State<Act2> {
ColorBloc _colorBloc;
@override
void didChangeDependencies() {
// Get the bloc in the 1st page
_colorBloc = Provider.of<ColorBloc>(context);
super.didChangeDependencies();
}
@override
Widget build(BuildContext context) {
return StreamBuilder<Response<ColorResponse>>(
// Use the bloc like in the 1st page
stream: _colorBloc.stream,
builder: (context, snapshot) {
if (snapshot.hasData) {
// ... other lines
小注意:使用 StreamBuilder 时,您可以启动值而无需重复代码。由于我不知道您的 Response
对象的结构,我以 Response(ColorResponse(color: Colors.green))
为例:
// ... other lines
@override
Widget build(BuildContext context) {
return Provider(
create: (_) => _bloc,
child: StreamBuilder<Response<ColorResponse>>(
// Initiate your data here
initialData: Response(ColorResponse(color: Colors.green)),
stream: _bloc.stream,
builder: (context, snapshot) {
if (snapshot.hasData) {
return Scaffold(
appBar: AppBar(
title: Text('First Route clicked'),
),
backgroundColor: snapshot.data.data.color,
// ... other lines
}
// Don't need to copy the above code block for the case when the data is not streamed yet
return Container(child: Center(child: CircularProgressIndicator()));
},
),
);
}