Flutter 如何在不同屏幕之间导航时使用StreamBuilder的通用实例
我试图实现一个简单的基本登录流,试图了解hoe流、BLoC和提供者的工作原理 这是我的模型- 对于firstName,我使用了streamController,而对于lastName,它只是一个简单的变量Flutter 如何在不同屏幕之间导航时使用StreamBuilder的通用实例,flutter,provider,bloc,stream-builder,Flutter,Provider,Bloc,Stream Builder,我试图实现一个简单的基本登录流,试图了解hoe流、BLoC和提供者的工作原理 这是我的模型- 对于firstName,我使用了streamController,而对于lastName,它只是一个简单的变量 class Authentication with ChangeNotifier { StreamController _firstNameStreamController = StreamController<String>.broadcast(); String la
class Authentication with ChangeNotifier {
StreamController _firstNameStreamController = StreamController<String>.broadcast();
String lastName = "lastName";
Sink get _firstNameSink => _firstNameStreamController.sink;
Stream<String> get firstNameStream => _firstNameStreamController.stream;
void populateFirstName(String fName) {
_firstNameSink.add(fName);
notifyListeners();
}
void populatelastName(String lName) {
lastName = lName;
notifyListeners();
}
void dispose() {
_firstNameStreamController.close();
}
}
使用ChangeNotifier进行类身份验证{
StreamController _firstNameStreamController=StreamController.broadcast();
字符串lastName=“lastName”;
Sink get _firstNameSink=>_firstNameStreamController.Sink;
Stream get firstNameStream=>\u firstNameStreamController.Stream;
void populateFirstName(字符串fName){
_firstNameSink.add(fName);
notifyListeners();
}
void populatelastName(字符串lName){
lastName=lName;
notifyListeners();
}
无效处置(){
_firstNameStreamController.close();
}
}
这是登录页面-
有两个文本字段,分别是firstName和lastName,还有一个提交按钮,用于导航到ProfilePage
class LoginPage extends StatelessWidget {
@override
Widget build(BuildContext context) {
return Scaffold(
body: Column(
children: [
//firstname
Consumer<Authentication>(
builder: (BuildContext context, value, Widget child) => TextField(
onSubmitted: (firstNameValue) {
value.populateFirstName(firstNameValue);
},
),
),
//lastname
Consumer<Authentication>(
builder: (BuildContext context, value, Widget child) => TextField(
onSubmitted: (lastNameValue) {
value.populatelastName(lastNameValue);
},
),
),
//submit
Consumer<Authentication>(
builder: (BuildContext context, value, Widget child) => RaisedButton(
onPressed: () {
Navigator.push(context, MaterialPageRoute(builder: (BuildContext context) => ProfilePage()));
},
child: StreamBuilder<String>(
stream: value.firstNameStream,
builder: (context, snapshot) {
return Text(snapshot.data ?? "Submit");
}
)
),
)
],
),
);
}
}
类登录页面扩展了无状态小部件{
@凌驾
小部件构建(构建上下文){
返回脚手架(
正文:专栏(
儿童:[
//名字
消费者(
生成器:(BuildContext上下文、值、小部件子项)=>TextField(
提交:(firstNameValue){
值。populateFirstName(firstNameValue);
},
),
),
//姓氏
消费者(
生成器:(BuildContext上下文、值、小部件子项)=>TextField(
onSubmitted:(lastNameValue){
值。populatelastName(lastNameValue);
},
),
),
//提交
消费者(
生成器:(BuildContext上下文、值、小部件子项)=>RaisedButton(
已按下:(){
push(context,materialpage(builder:(BuildContext context)=>ProfilePage());
},
孩子:StreamBuilder(
流:value.firstNameStream,
生成器:(上下文,快照){
返回文本(snapshot.data??“提交”);
}
)
),
)
],
),
);
}
}
在这里,当我在FirstTextField中提交firstName时,StreamBuilder正在正确更新,这很好
现在进入个人资料页面-
我试图同时显示firstName(使用streamBuilder)和lastName(简单变量),但是firstName没有正确显示(我在上一页的textfield中输入的),但是lastName没有问题
class ProfilePage extends StatelessWidget {
@override
Widget build(BuildContext context) {
return Scaffold(
body: Column(
children: [
Consumer<Authentication>(
builder: (BuildContext context, value, Widget child) => StreamBuilder<String>(
stream: value.firstNameStream,
builder: (context, snapshot) {
return Text(snapshot.data);
}
),
),
Consumer<Authentication>(
builder: (BuildContext context, value, Widget child) => Text(value.lastName),
),
],
),
);
}
}
class ProfilePage扩展了无状态小部件{
@凌驾
小部件构建(构建上下文){
返回脚手架(
正文:专栏(
儿童:[
消费者(
生成器:(BuildContext上下文、值、小部件子项)=>StreamBuilder(
流:value.firstNameStream,
生成器:(上下文,快照){
返回文本(snapshot.data);
}
),
),
消费者(
生成器:(BuildContext上下文、值、小部件子项)=>Text(value.lastName),
),
],
),
);
}
}
那么,为什么当接收器和流都在同一个页面(小部件)(在本例中为LoginPage)上完成时,StreamBuilder工作,而当接收器在一个页面(LoginPage)上完成,流在另一个页面(ProfilePage)上完成时,StreamBuilder不工作呢
我认为这不是提供者的问题,因为lastName(简单变量)显示得很好