【发布时间】：2021-04-29 08:51:48
【问题描述】：
我正在创建一个应用程序，我必须在其中更改按钮的状态并保存状态。然后当该页面再次打开时，应显示更改后的状态。
例如：如果我单击收藏按钮，则其状态从未选择更改为已选择，因此在此之后，当我关闭应用程序并再次打开它时，收藏按钮应处于已选择状态而不是未选择状态。
请帮我解决这个问题。
我使用了一个变量来存储值，然后我正在检查条件。
import 'package:EventsApp/Models/EventModel.dart';
import 'package:flutter/material.dart';
import 'package:fluttertoast/fluttertoast.dart';
import 'package:http/http.dart' as http;
import 'package:favorite_button/favorite_button.dart';
import 'package:shared_preferences/shared_preferences.dart';
class DetailPage extends StatefulWidget {
final String image;
final EventModel value;
const DetailPage({Key key, this.image, @required this.value})
: super(key: key);
@override
_DetailPageState createState() => _DetailPageState();
}
class _DetailPageState extends State<DetailPage> {
String eventId;
String userId;
bool isPartcipated = false;
bool isfavorite;
Future<http.Response> participateinEvent() async {
SharedPreferences prefs = await SharedPreferences.getInstance();
var uid = prefs.getString('userId');
var eveid = prefs.getString('eventId');
var res = await http.post(
'http://10.0.2.2:8080/eventusermapping/addParticipant/' +
uid +
'/' +
eveid);
print(res.body);
Fluttertoast.showToast(
msg: 'Participation Successful',
toastLength: Toast.LENGTH_SHORT,
gravity: ToastGravity.BOTTOM,
timeInSecForIos: 1,
);
}
Future<http.Response> addfavorite() async {
SharedPreferences prefs = await SharedPreferences.getInstance();
var uid = prefs.getString('userId');
var eveid = prefs.getString('eventId');
var res = await http
.post('http://10.0.2.2:8080/event/addtoFavorites/' + uid + '/' + eveid);
Fluttertoast.showToast(
msg: 'Added to favorite',
toastLength: Toast.LENGTH_SHORT,
gravity: ToastGravity.BOTTOM,
timeInSecForIos: 1,
);
setState(() {
isfavorite = true;
});
}
Future<http.Response> removefavorite() async {
SharedPreferences prefs = await SharedPreferences.getInstance();
var uid = prefs.getString('userId');
var eveid = prefs.getString('eventId');
var res = await http.post(
'http://10.0.2.2:8080/event/removeFromFavorites/' + uid + '/' + eveid);
Fluttertoast.showToast(
msg: 'Removed from favorite',
toastLength: Toast.LENGTH_SHORT,
gravity: ToastGravity.BOTTOM,
timeInSecForIos: 1,
);
setState(() {
isfavorite = false;
});
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: new AppBar(
leading: IconButton(
icon: Icon(Icons.arrow_back, color: Color(0xffffffff)),
onPressed: () => Navigator.of(context).pop(),
),
centerTitle: true,
backgroundColor: Colors.lightBlue[900],
elevation: 0.0,
title: new Text("Event Details",
style: const TextStyle(
color: const Color(0xffffffff),
fontWeight: FontWeight.w500,
fontStyle: FontStyle.normal,
fontSize: 19.0)),
),
body: Container(
child: SingleChildScrollView(
child: Column(
children: [
Container(
width: double.infinity,
height: 400.0,
child: Stack(
children: [
Positioned(
top: 0,
left: 0,
right: 0,
bottom: 90,
child: Container(
decoration: BoxDecoration(
image: DecorationImage(
image: NetworkImage('${widget.value.coverimg}'),
fit: BoxFit.fitWidth,
),
),
// child: Column(
// children: [
// IconButton(
// icon: Icon(Icons.arrow_back),
// onPressed: () => Navigator.pop(context),
// iconSize: 30.0,
// color: Colors.lightBlue[900],
// ),
// ],
// ),
),
),
Positioned(
top: 270,
left: 20,
right: 20,
bottom: 0,
child: Card(
elevation: 0.5,
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.circular(25.0),
),
child: Padding(
padding: EdgeInsets.all(15.0),
child: Column(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: [
Row(
mainAxisAlignment:
MainAxisAlignment.spaceBetween,
children: [
Text(
'${widget.value.name}',
style: TextStyle(
fontSize: 23.0,
fontWeight: FontWeight.bold,
color: Colors.lightBlue[900]),
),
],
),
Row(
children: [
Icon(
Icons.location_on,
color: Colors.grey,
size: 20,
),
SizedBox(width: 12.0),
Text(
" Kalyan west",
style: TextStyle(
fontSize: 18,
color: Colors.lightBlue[900]),
),
],
),
Row(
children: [
Icon(
Icons.calendar_today,
color: Colors.grey,
size: 20,
),
SizedBox(width: 12.0),
Text(
'${widget.value.date}',
style: TextStyle(
fontSize: 17,
color: Colors.lightBlue[900]),
),
],
),
],
),
),
),
),
],
),
),
Container(
width: double.infinity,
child: Column(
children: [
SizedBox(height: 12.0),
ListTile(
leading: CircleAvatar(
radius: 25,
backgroundImage:
NetworkImage('${widget.value.eventheadphoto}'),
),
title: Text(
'${widget.value.eventheadname}',
style: TextStyle(
fontWeight: FontWeight.bold,
fontSize: 20,
color: Colors.lightBlue[900]),
),
subtitle: Text(
"Event Head",
style: TextStyle(fontSize: 17, color: Colors.grey),
),
),
SizedBox(height: 15.0),
Padding(
padding: EdgeInsets.symmetric(horizontal: 18),
child: Text(
'${widget.value.description}',
textAlign: TextAlign.left,
style: TextStyle(
fontSize: 19, color: Colors.lightBlue[900]),
),
),
SizedBox(height: 20.0),
Container(
child: Row(
children: [
Padding(
padding: const EdgeInsets.only(left: 70.0),
child: Center(
child: SizedBox(
width: 190,
child: isPartcipated
? RaisedButton(
onPressed: null,
shape: RoundedRectangleBorder(
borderRadius:
BorderRadius.circular(30.0)),
color: Colors.grey,
child: Text(
"Participated",
style: TextStyle(
color: Colors.white,
fontSize: 18.0,
letterSpacing: 1.5),
),
disabledColor: Colors.black12,
disabledElevation: 1,
disabledTextColor: Colors.black,
)
: RaisedButton(
onPressed: () {
participateinEvent();
setState(() {
isPartcipated = !isPartcipated;
});
},
shape: RoundedRectangleBorder(
borderRadius:
BorderRadius.circular(30.0)),
color: Colors.lightBlue[900],
child: Text(
"Participate",
style: TextStyle(
color: Colors.white,
fontSize: 18.0,
letterSpacing: 1.5),
),
),
),
),
),
Padding(
padding: EdgeInsets.only(left: 50.0),
child: Container(
decoration: BoxDecoration(
// borderRadius: BorderRadius.circular(50),
// color: Colors.blue,
// border:
// Border.all(width: 1, color: Colors.grey),
),
child: FavoriteButton(
isFavorite: false,
valueChanged: (isfavorite) {
if (isfavorite) {
addfavorite();
} else {
removefavorite();
}
},
), //IconButton(
// iconSize: 35,
// color: Colors.redAccent[400],
// icon: Icon(Icons.favorite_border),
// tooltip: 'Add to Favorite',
// onPressed: () {}),
),
)
],
),
),
SizedBox(height: 30.0)
],
),
)
],
),
),
),
);
}
}
【问题讨论】：
-
你可以使用
SharedPreferences。 -
不，我试过了，它不起作用，你能举个例子，我该怎么做，可能是我做错了
-
或许可以向我们展示您的尝试？
-
好的，我会放代码
-
我已经添加了你可以看到的代码并给出建议