我有一个有状态的小部件,该小部件从其父级获取一个块:
class Page extends StatefulWidget {
@override
State<StatefulWidget> createState() =>
_PageState();
}
class _PageState extends State<Page> {
final TextEditingController mnemonicController = TextEditingController();
final _scaffoldKey = GlobalKey<ScaffoldState>();
@override
Widget build(BuildContext context) {
final MnemonicLogicBloc mnemonicLogicBloc =
BlocProvider.of<MnemonicLogicBloc>(context);
mnemonicLogicBloc.outCheckMnemonic.listen((isCorrect){
if (!isCorrect) {
SnackBar copySnack = SnackBar(content: Text('Wrong Mnemonic!'));
_scaffoldKey.currentState.showSnackBar(copySnack);
}
});
return Scaffold(
key: _scaffoldKey,
body: Container(
width: double.infinity,
child: Column(
crossAxisAlignment: CrossAxisAlignment.center,
children: <Widget>[
Container(
child: TextField(
controller: mnemonicController,
),
),
RaisedButton(
onPressed: () {
mnemonicLogicBloc.isMnemonicCorrect(mnemonicController.text);
},
child: Text('Check', style: TextStyle(color: Colors.white)),
)
],
),
));
}
}
我要检查的是,当用户按下按钮时,是否插入正确的字符串。我在bloc中调用的方法是:
void isMnemonicCorrect(String typedMnemonic){
if(typedMnemonic == _lastGeneratedMnemonic)
_inCheckMnemonic.add(true);
else
_inCheckMnemonic.add(false);
}
_inCheckMnemonic是我的主题的接收器(我正在使用rxDart),而outCheckMnemonic是我的Stream。问题是,即使一次调用了块的'isCorrect'方法,该监听回调也被调用了两次(SnackBar被显示了两次)。为什么会这样?
编辑:我仅使用Navigator.push导航到Page():
Navigator.of(context).push(MaterialPageRoute(
builder: (BuildContext context) {
return Page();
}));
我能够检索该bloc,因为在我的应用启动时,我初始化了bloc:
return runApp(BlocProvider<ApplicationBloc>(
bloc: ApplicationBloc(),
child: BlocProvider<MnemonicLogicBloc>(
bloc: MnemonicLogicBloc(),
child: BlocProvider<HomePageBloc>(
bloc: HomePageBloc(),
child: App(),
),
)
));
答案 0 :(得分:2)
在Widget
中添加新的Navigator
时,请避免在构建器内部创建该小部件,而应在外部声明变量并在构建器中重新使用该变量,如下所示:
final page = Page();
Navigator.of(context).push(MaterialPageRoute(
builder: (BuildContext context) => page ), );
通过此更改,我们避免了以意外方式多次重新创建窗口小部件。