我已经创建了一个主页，该用户可以登录该应用程序，然后在下一个屏幕中，用户可以看到其个人资料信息（仅个人资料名称），并在其下方是“退出”按钮。用户可以使用signOut按钮从应用程序中注销。但这对我不起作用。
我想通过在details.dart中按signOut按钮从main.dart调用signOut方法（两个类都在不同的文件中）
但是当我在details.dart中按下signOut Button时，什么也没有发生！
代码如下：
主镖
import 'dart:async';
import 'package:flutter/material.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:google_sign_in/google_sign_in.dart';
import 'details.dart';
void main() => runApp(new MyApp());
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return new MaterialApp(
theme: new ThemeData(
primarySwatch: Colors.blue,
),
debugShowCheckedModeBanner: false,
home: new MyHomePage(),
);
}
}
class MyHomePage extends StatefulWidget {
@override
MyHomePageState createState() => MyHomePageState();
}
class MyHomePageState extends State<MyHomePage> {
final FirebaseAuth firebaseAuth = FirebaseAuth.instance;
final GoogleSignIn googleSignIn = GoogleSignIn();
static bool _LoginButton = true;
void signOut(){
googleSignIn.signOut();
setState((){
_LoginButton = true;
});
print(_LoginButton);
print("User Signed Out");
}
Future<FirebaseUser> _signIn() async{
if(_LoginButton==true){
setState((){
_LoginButton=false;
});
GoogleSignInAccount googleSignInAccount = await googleSignIn.signIn();
GoogleSignInAuthentication googleSignInAuthentication = await googleSignInAccount.authentication;
FirebaseUser firebaseUser = await firebaseAuth.signInWithGoogle(idToken: googleSignInAuthentication.idToken, accessToken: googleSignInAuthentication.accessToken);
print("Username is "+firebaseUser.displayName);
setState((){
_LoginButton = true;
});
Navigator.push(context, MaterialPageRoute(builder: (context) => details(firebaseUser.displayName,signOut)));
return firebaseUser;
}
}
bool _LoginButtonBool(){
return _LoginButton;
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(title: Text("Google auth with firebase"),),
body: Center(
child: _LoginButtonBool()?Container(
child: Column(
mainAxisAlignment: MainAxisAlignment.spaceAround,
children: <Widget>[
MaterialButton(onPressed: _LoginButtonBool() ? () => _signIn().then((FirebaseUser firebaseuser ) =>print(firebaseuser)).catchError((e) => print(e)): null,
child: Text("Login"),color: Colors.orange,),
],
),
):CircularProgressIndicator(backgroundColor: Colors.greenAccent.withOpacity(0.01),),
),
);
}
}
details.dart
import 'package:flutter/material.dart';
import 'package:flutter_auth/main.dart';
class details extends StatelessWidget {
String name;
final Function callback;
details(this.name,this.callback);
@override
Widget build(BuildContext context) {
return Scaffold(
body:Center(child: Column(
mainAxisAlignment: MainAxisAlignment.spaceAround,
children: <Widget>[
Text(name),
MaterialButton(onPressed: () => callback,
child: Text("Log out"),color: Colors.orange),
],
),),
);
}
}
您必须小心尝试执行的操作，因为您可能正在访问未安装的页面/小部件。想象一下你做了一个pushReplacement(new MaterialPageroute(...)). 上一页在树中不再可用，因此您无法访问它或其任何方法。
除非您的树中有明确的父子关系，否则您应该将逻辑抽象为外部或业务逻辑类。因此，您确定您正在调用类的活动实例。
以下是您可以使用的传递 Business 对象的示例。如果您使用其他模式，如 BLOC、ScopedModel、Streams 等，那就更好了。但为了简单起见，我认为这应该足够了。
import "package:flutter/material.dart";
void main() {
runApp(MyApp(new Logic()));
}
class Logic {
void doSomething() {
print("doing something");
}
}
class MyApp extends StatelessWidget {
final Logic logic;
MyApp(this.logic);
@override
Widget build(BuildContext context) {
return new MaterialApp(
home: new HomePage(widget.logic),
);
}
}
class HomePage extends StatelessWidget {
final Logic logic;
HomePage(this.logic);
@override
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child: FlatButton(
onPressed: () { Navigator.of(context).pushReplacement(
MaterialPageRoute(
builder: (context) => AnotherPage(logic),
))},
child: Text("Go to AnotherPage"),
),
),
);
}
}
class AnotherPage extends StatelessWidget {
final Logic logic;
AnotherPage(this.logic);
@override
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child: FlatButton(
onPressed: logic.doSomething,
child: Text("Press me"),
),
),
);
}
}
如果您仍想调用另一个 Page 中的函数，并且您确定该页面已安装（您执行的是 apush而不是 a pushReplacement），您可以执行以下操作。（小心轻放）
class HomePage extends StatelessWidget {
HomePage();
void onCalledFromOutside() {
print("Call from outside");
}
@override
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child: FlatButton(
onPressed: () { Navigator.of(context).push(
MaterialPageRoute(
builder: (context) => AnotherPage(onCalledFromOutside),
))},
child: Text("Go to AnotherPage"),
),
),
);
}
}
class AnotherPage extends StatelessWidget {
final Function callback
AnotherPage(this.callback);
@override
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child: FlatButton(
onPressed: callback,
child: Text("Press me"),
),
),
);
}
}
很简单让我用一个例子来解释
class Animals
{
var animalList = ['dog','cat','cow'];
// function for printing the list of animals
void animalListPrinter(){
for(var animal in animalList){
print(animal);
}
}
}
将上述函数调用到另一个类
class ShowingAnimalList extends StatelessWidget {
final Animals ani= new Animals();
@override
Widget build(BuildContext context) {
return GestureDetector(
onTap:()=> ani.animalListPrinter(),
);
}
}
你可以从父类调用任何小部件
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