我想在用户成功登录flutter后保持用户登录状态。我正在使用 REST API 来检索用户的用户名和密码。但我想保存这些详细信息，以便用户可以保持登录状态。我目前的情况是我可以成功登录用户，但是当我重新启动应用程序时，我必须再次登录，因此我需要将用户的详细信息保存在共享首选项，以便用户可以在整个会话中保持登录状态，直到注销。但我无法这样做，所以请帮助我。提前致谢
登录.dart
Widget build(BuildContext context) {
return Scaffold(
backgroundColor: Color.fromRGBO(3, 9, 23, 1),
body: Container(
padding: EdgeInsets.only(
top: 100,
right: 30,
left: 30,
),
child: SingleChildScrollView(
child: Form(
key: _formKey,
child: Column(
crossAxisAlignment: CrossAxisAlignment.center,
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
FadeAnimation(
1.2,
Container(
padding: EdgeInsets.all(70.0),
margin: EdgeInsets.only(bottom: 50.0),
decoration: BoxDecoration(
image: DecorationImage(
image: AssetImage(
'assets/images/trakinglogo.png'))),
)),
SizedBox(
height: 30,
),
FadeAnimation(
1.5,
Container(
padding: EdgeInsets.all(10),
decoration: BoxDecoration(
borderRadius: BorderRadius.circular(10),
color: Colors.white),
child: Column(
children: <Widget>[
Container(
decoration: BoxDecoration(
border: Border(
bottom:
BorderSide(color: Colors.grey[300]))),
child: TextFormField(
controller: _emailController,
onFieldSubmitted: (_) =>
FocusScope.of(context).nextFocus(),
textInputAction: TextInputAction.done,
validator: (value) {
if (value.isEmpty) {
return 'Email is required';
}
return null;
},
decoration: InputDecoration(
border: InputBorder.none,
hintStyle: TextStyle(
color: Colors.grey.withOpacity(.8)),
hintText: "Votre adresse mail"),
),
),
Container(
decoration: BoxDecoration(),
child: TextFormField(
controller: _passwordController,
validator: (value) {
if (value.isEmpty) {
return 'Password is required';
}
return null;
},
obscureText: _isHidden,
decoration: InputDecoration(
border: InputBorder.none,
hintStyle: TextStyle(
color: Colors.grey.withOpacity(.8)),
hintText: "Mot de passe",
suffix: InkWell(
onTap: _togglePasswordView,
child: Icon(
_isHidden
? (CommunityMaterialIcons
.eye_outline)
: (CommunityMaterialIcons.eye_off),
color: Color(0xFF939394),
SizedBox(
height: 40,
),
FadeAnimation(
1.8,
Center(
child: Column(
children: [
Row(
mainAxisAlignment: MainAxisAlignment.center,
crossAxisAlignment: CrossAxisAlignment.center,
children: [
Container(
child: RaisedButton(
textColor: Colors.white,
color: kPrimaryColor,
child: Text("Se connecter"),
onPressed: () async {
if (_formKey.currentState.validate()) {
showDialog(
context: context,
builder: (BuildContext context) {
return Center(
child:
CircularProgressIndicator(),
);
});
await loginUser();
}
/* Navigator.push(
context,
MaterialPageRoute(
builder: (context) => MyWidget()),
);*/
// Navigator.pushNamed(context, 'Mywidget');
},
shape: new RoundedRectangleBorder(
borderRadius:
new BorderRadius.circular(30.0),
),
),
width: 250,
padding: EdgeInsets.all(15),
)
],
),
Row(
mainAxisAlignment: MainAxisAlignment.center,
children: [
AlreadyHaveAnAccountCheck(
press: () {
Navigator.push(
context,
MaterialPageRoute(
builder: (context) {
return SignUp();
void loginUser() async {
// if (_formKey.currentState.validate()) {
setState(() {
_isLoading = true;
});
String email = _emailController.text;
String password = _passwordController.text;
authentication.login(email, password).then((user) {
if (user != null)
Navigator.push(
context, MaterialPageRoute(builder: (context) => MyWidget()));
}).catchError((error) {
ScaffoldMessenger.of(context)
.showSnackBar(SnackBar(content: Text(error.toString())));
});
setState(() {
_isLoading = false;
});
}
这是登录功能：
Future<User> login(String email, String password) async {
await checkInternet();
Map<String, String> headers = {
'Content-type': 'application/json',
'Accept': 'application/json',
};
Map<String, String> body = {'email': email, 'password': password};
var response = await http.post(Uri.parse(ApiUtil.AUTH_LOGIN),
headers: headers, body: jsonEncode(body));
switch (response.statusCode) {
case 200:
var body = jsonDecode(response.body);
var data = body['user'];
User user = User.fromJson(data);
Track track = Track.fromJson(body);
if (body['code'] == 0) {
SharedPreferences localStorage =
await SharedPreferences.getInstance();
localStorage.setInt('id', body['user']['id']);
localStorage.setString('adress', body['user']['adress']);
localStorage.setString('phone', body['user']['phone']);
localStorage.setString('access_token', body['access_token']);
localStorage.setString('user', json.encode(body['user']));
String user = localStorage.getString('user');
}
return user;
case 500:
throw ('Erreur serveur');
break;
case 400:
throw LoginFailed();
default:
throw ('connection timeout');
break;
}
}
答案 0 :(得分：0)
创建一个类 AppSharedPreference 并在该类中创建这些方法：
User 是您的 modal 类。
保存用户：
static saveUser(String key, User value) async {
final prefs = await SharedPreferences.getInstance();
//We cannot save custom objects.
//So json.encode is used to convert User Object to Json a string.
prefs.setString(key, json.encode(value));
}
获取用户：
static readUser(String key) async {
final prefs = await SharedPreferences.getInstance();
//json.decode to convert json string back to Json Object
return json.decode(prefs.getString(key));
}
确保您的模态 User 类包含 toJson 方法：
Map<String, String> toJson() => {
'id': Id,
'address': address,
'phone': phone,
// rest of your attributes...
};
调用 saveUser 方法：
await AppSharedPreference.saveUser('your_key', user);
调用 readUser 方法：
（确保您的模态 User 类包含 fromJson 方法）
User user = User.fromJson(await AppSharedPreference.readUser('your_key'));
然后您可以检查 user 是否为 null。如果是 null，则表示没有数据且 user 未登录。
如果您想要 logout 用户，您可以创建一个方法从 SharedPreference 中删除用户：
删除用户：
static removeUser(String key) async {
final prefs = await SharedPreferences.getInstance();
prefs.remove(key);
}
调用 removeUser 方法：
await AppSharedPreference.removeUser('your_key');
答案 1 :(得分：0)
您必须在应用程序启动时检查 sharedPreference 中是否有数据，然后根据该数据重定向用户。一个例子是在闪屏中实现这个
import 'dart:async';
import 'package:flutter/material.dart';
import 'package:shared_preferences/shared_preferences.dart';
import 'home_page.dart';
import 'login_page.dart';
class SplashScreen extends StatefulWidget {
static const String splashRoute = '/';
@override
_SplashScreenState createState() => _SplashScreenState();
}
class _SplashScreenState extends State<SplashScreen> {
void timeToShowSplashScreenOnScreen() async {
Timer(Duration(seconds: 3), () async {
if (!mounted) return;
SharedPreferences _prefs = await SharedPreferences.getInstance();
bool isLoggedIn = _prefs.getBool("loggedIn");
if (isLoggedIn != null && isLoggedIn) {
Navigator.of(context).pushNamedAndRemoveUntil(HomePage.homePageRoute, (route) => false);
} else {
Navigator.of(context).pushNamedAndRemoveUntil(LoginPage.loginRoute, (route) => false);
}
});
}
@override
void initState() {
super.initState();
timeToShowSplashScreenOnScreen();
}
@override
Widget build(BuildContext context) {
double _width = MediaQuery.of(context).size.width;
double _height = MediaQuery.of(context).size.height;
return Scaffold(
body: Container(
width: _width,
height: _height,
child: Stack(
children: [
// Your UI for splash screen
],
),
),
);
}
}
这个例子使用存储在 prefs 中的布尔值，但你也可以用字符串做类似的事情。