我正在尝试在此代码上的应用程序（在主屏幕中）内部的应用程序中创建通知徽章，并且我将Firebase Cloud Messaging与flutter语言的android应用程序一起使用，问题是我不知道如何计算收到通知
有没有建议的方法来计算从Firebase Cloud Messaging到Android应用程序的接收通知数量？
PS：我现在更新了以下答案的代码，但仍然出现错误
// import 'package:flutter/foundation.dart';
// import 'package:flappy_search_bar/flappy_search_bar.dart';
import 'dart:developer';
import 'package:flutter/material.dart';
import 'package:flutter/rendering.dart';
import 'package:mycafe/main.dart';
import 'Custom_Text.dart';
import 'Pasta.dart';
import 'Burger.dart';
import 'Pizza.dart';
import 'AboutUs.dart';
import 'dart:async';
import 'ui/home/HomeScreen.dart';
import 'dart:math';
import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'ContactUs.dart';
import 'package:flutter/services.dart';
import 'package:mycafe/model/User.dart';
import 'package:mycafe/ui/home/HomeScreen.dart';
import 'package:mycafe/ui/services/Authenticate.dart';
import 'package:mycafe/ui/utils/helper.dart';
import 'package:shared_preferences/shared_preferences.dart';
import 'dart:async';
import 'dart:io';
import 'package:flushbar/flushbar.dart';
import 'package:flushbar/flushbar_helper.dart';
// import 'package:flutter/material.dart';
import 'package:firebase_messaging/firebase_messaging.dart';
import 'package:cloud_firestore/cloud_firestore.dart';
import 'constants.dart' as Constants;
import 'ui/auth/AuthScreen.dart';
import 'ui/onBoarding/OnBoardingScreen.dart';
import 'package:flutter/cupertino.dart';
import 'package:mycafe/ui/auth/AuthScreen.dart';
var bannerItems = ["Burger", "cheesechilly", "Noodles", "Pizza"];
var bannerImages = [
"images/burger.jpg",
"images/cheesechilly.jpg",
"images/noodles.jpg",
"images/pizza.jpg"
];
ValueNotifier<int> notificationCounterValueNotifer = ValueNotifier(0);
class Notify extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'FlutterBase',
home: Scaffold(
body: MessageHandler(),
),
);
}
}
class MessageHandler extends StatefulWidget {
@override
_MessageHandlerState createState() => _MessageHandlerState();
}
class _MessageHandlerState extends State<MessageHandler> with ChangeNotifier {
final Firestore _db = Firestore.instance;
final FirebaseMessaging _fcm = FirebaseMessaging();
StreamSubscription iosSubscription;
@override
void initState() {
super.initState();
if (Platform.isIOS) {
iosSubscription = _fcm.onIosSettingsRegistered.listen((data) {
print(data);
_saveDeviceToken();
});
_fcm.requestNotificationPermissions(IosNotificationSettings());
} else {
_saveDeviceToken();
}
// void _incrementCounter() {
_fcm.configure(
onMessage: (Map<String, dynamic> message) async {
print("onMessage: $message");
// RaisedButton(
// child: Text(message['notification']['title']),
// onPressed: () {
// Flushbar(
// flushbarPosition: FlushbarPosition.TOP,
// icon: Icon(
// Icons.notifications_active,
// color: Colors.white,
// ),
// mainButton: FlatButton(
// onPressed: () {
// Navigator.pop(context);
// // Flush.showGoodFlushbar(context, 'login successful!');
// },
// // child: Text(
// // "ADD",
// // style: TextStyle(color: Colors.amber),
// // ),
// ),
// // duration: Duration(seconds: 7))
// ).show(context);
// },
// );
notificationCounterValueNotifer.value++;
notificationCounterValueNotifer
.notifyListeners(); // notify listeners here so ValueListenableBuilder will build the widget.
final snackbar = SnackBar(
content: Text(message['notification']['title']),
action: SnackBarAction(
label: 'Go',
onPressed: () => null,
),
);
Scaffold.of(context).showSnackBar(snackbar);
// showDialog(
// context: context,
// builder: (context) => AlertDialog(
// content: ListTile(
// title: Text(message['notification']['title']),
// subtitle: Text(message['notification']['body']),
// ),
// actions: <Widget>[
// FlatButton(
// color: Colors.amber,
// child: Text('Ok'),
// onPressed: () => Navigator.of(context).pop(),
// ),
// ],
// ),
// );
},
onLaunch: (Map<String, dynamic> message) async {
print("onLaunch: $message");
// TODO optional
},
onResume: (Map<String, dynamic> message) async {
print("onResume: $message");
// TODO optional
},
);
}
@override
void dispose() {
if (iosSubscription != null) iosSubscription.cancel();
super.dispose();
}
@override
Widget build(BuildContext context) {
// _handleMessages(context);
return MaterialApp(home: Scaffold(body: HomeApp()));
}
/// Get the token, save it to the database for current user
_saveDeviceToken() async {
// Get the current user
String uid = 'jeffd23';
// FirebaseUser user = await _auth.currentUser();
// Get the token for this device
String fcmToken = await _fcm.getToken();
// Save it to Firestore
if (fcmToken != null) {
var tokens = _db
.collection('users')
.document(uid)
.collection('tokens')
.document(fcmToken);
await tokens.setData({
'token': fcmToken,
'createdAt': FieldValue.serverTimestamp(), // optional
'platform': Platform.operatingSystem // optional
});
}
}
/// Subscribe the user to a topic
_subscribeToTopic() async {
// Subscribe the user to a topic
_fcm.subscribeToTopic('puppies');
}
}
Widget myAppBarIcon() {
if (State is ValueNotifier) {
return ValueListenableBuilder(
builder: (BuildContext context, int newNotificationCounterValue,
Widget child) {
// return Container(
// width: 50,
// height: 10,
child:
Stack(
children: [
Icon(
Icons.notifications,
color: Colors.white,
size: 30,
),
Container(
width: 30,
height: 30,
alignment: Alignment.topRight,
margin: EdgeInsets.only(top: 2),
child: Container(
width: 15,
height: 15,
decoration: BoxDecoration(
shape: BoxShape.circle,
color: Color(0xffc32c37),
border: Border.all(color: Colors.white, width: 1)),
child: Padding(
padding: const EdgeInsets.all(0.0),
child: Text(
newNotificationCounterValue.toString(),
),
),
),
),
],
);
//return your badge here
},
valueListenable: notificationCounterValueNotifer,
);
// return Container(
// width: 50,
// height: 10,
// child: Stack(
// children: [
// Icon(
// Icons.notifications,
// color: Colors.white,
// size: 30,
// ),
// Container(
// width: 30,
// height: 30,
// alignment: Alignment.topRight,
// margin: EdgeInsets.only(top: 2),
// child: Container(
// width: 15,
// height: 15,
// decoration: BoxDecoration(
// shape: BoxShape.circle,
// color: Color(0xffc32c37),
// border: Border.all(color: Colors.white, width: 1)),
// child: Padding(
// padding: const EdgeInsets.all(0.0),
// child: Center(
// child: ValueListenableBuilder(),
// ),
// ),
// ),
// ),
// ],
// ),
// );
} else {
return Container();
}
}
class HomeApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
backgroundColor: Colors.deepOrange[900],
title: Text('HuQQa BuzZ'),
actions: <Widget>[myAppBarIcon()],
答案 0 :(得分：2)
这是我的方法：
//define a global variable
ValueNotifier<int> notificationCounterValueNotifer =
ValueNotifier(0);
您可以阅读有关ValueNotifier here的信息。
然后，当您收到新通知时，将该值增加1：
_fcm.configure(
onMessage: (Map<String, dynamic> message) async {
print("onMessage: $message");
notificationCounterValueNotifer.value++;
notificationCounterValueNotifer.notifyListeners(); // notify listeners here so ValueListenableBuilder will build the widget.
// final snackbar = SnackBar(
// content: Text(message['notification']['title']),
// action: SnackBarAction(
// label: 'Go',
// onPressed: () => null,
// ),
// );
// Scaffold.of(context).showSnackBar(snackbar);
showDialog(
context: context,
builder: (context) => AlertDialog(
content: ListTile(
title: Text(message['notification']['title']),
subtitle: Text(message['notification']['body']),
),
actions: <Widget>[
FlatButton(
color: Colors.amber,
child: Text('Ok'),
onPressed: () => Navigator.of(context).pop(),
),
],
),
);
},
);
为了通知侦听器，您必须将ChangeNotifer作为混合添加到您的班级：
class _MessageHandlerState extends State<MessageHandler> with ChangeNotifier
只要值更改，就可以选择ValueListenableBuilder来构建窗口小部件。为了更新徽章，我们使用以下小部件：
ValueListenableBuilder(
builder: (BuildContext context, int newNotificationCounterValue, Widget child) {
// This builder will only get called when the notificationCounterValueNotifer is updated.
return Text(newNotificationCounterValue.toString()); //return your badge here
},
valueListenable: notificationCounterValueNotifer,
);
您可以将值存储在数据库文档中，并在应用程序的开头进行分配，以使notificationCounterValueNotifer的值不为0。
如果需要，可以在导航到notificationScreen时再次将其设置为0。
也许有更好的方法可以做到这一点，但这就是我的方法。
更新：
您需要从ValueListenableBuilder返回myAppBarIcon：
Widget myAppBarIcon() {
//you have to return the widget from builder method.
//you can add logics inside your builder method. for example, if you don't want to show a badge when the value is 0.
return ValueListenableBuilder(
builder: (BuildContext context, int newNotificationCounterValue,
Widget child) {
//returns an empty container if the value is 0 and returns the Stack otherwise
return newNotificationCounterValue == 0? Container(): Stack(
children: [
Icon(
Icons.notifications,
color: Colors.white,
size: 30,
),
Container(
width: 30,
height: 30,
alignment: Alignment.topRight,
margin: EdgeInsets.only(top: 2),
child: Container(
width: 15,
height: 15,
decoration: BoxDecoration(
shape: BoxShape.circle,
color: Color(0xffc32c37),
border: Border.all(color: Colors.white, width: 1)),
child: Padding(
padding: const EdgeInsets.all(0.0),
child: Text(
newNotificationCounterValue.toString(),
),
),
),
),
],
);
},
valueListenable: notificationCounterValueNotifer,
);
}