//eg: if you give /Nexpage3 in the status field then it will navigate to Nextpage3 of your App
第一个信息标题在你的Firebase云信息传递页面中的部分被称为通知数据[当应用程序被最小化或关闭时，它将显示为一个通知]。
位于网页底部的第二个信息标题部分被称为信息数据。它将以通知或警报对话的形式显示在应用程序内部，这取决于你的愿望。
STEPS
创建一个假的项目，然后使用Firebase消息插件，在这个盒子里把宝马汽车作为
主题，然后点击订阅
现在去你的控制台，然后发送一条格式为FollowOWING的信息，它必须包含Id和Status键，因为我们正在解析Id和Status键，以便用Status键的值显示NextPage，但如果你喜欢标题或正文这样的字段，你也可以这样做，但要确保在你的flutter代码中解析map值。
//THIS IS A LITTLE BIT MODIFIED VERSION OF Example Code given in Firebase
//Messaging Plugin
//WHEN U PASTE THE CODE IN UR VS CODE OR ANDROID STUDIO PLEASE Format the
//Document because it is aligned in single lines
import 'dart:async';
import 'package:firebase_messaging/firebase_messaging.dart';
import 'package:flutter/material.dart';
void main() {
runApp(
new MaterialApp(
home: new PushMessagingExample(),
routes: <String,WidgetBuilder>{
"/Nexpage1":(BuildContext context)=> new Nexpage1(),
"/Nexpage2":(BuildContext context)=> new Nexpage2(),
"/Nexpage3":(BuildContext context)=> new Nexpage3(),
} ),);}
//INITIAL PARAMETERS
String _homeScreenText = "Waiting for token...";
bool _topicButtonsDisabled = false;
final FirebaseMessaging _firebaseMessaging = new FirebaseMessaging();
final TextEditingController _topicController = new TextEditingController(text: 'topic');
final Map<String, Item> _items = <String, Item>{};
Item _itemForMessage(Map<String, dynamic> message) {
final String itemId = message['id'];
final Item item = _items.putIfAbsent(itemId, () => new Item(itemId: itemId))..status = message['status'];
return item;
//MAIN CLASS WHICH IS THE HOMEPAGE
class PushMessagingExample extends StatefulWidget {
@override
_PushMessagingExampleState createState() => new _PushMessagingExampleState();
class _PushMessagingExampleState extends State<PushMessagingExample> {
void _navigateToItemDetail(Map<String, dynamic> message) {
final String pagechooser= message['status'];
Navigator.pushNamed(context, pagechooser);
//CLEAR TOPIC
void _clearTopicText() {setState(() {_topicController.text = "";_topicButtonsDisabled = true;});}
//DIALOGUE
void _showItemDialog(Map<String, dynamic> message) {showDialog<bool>(context: context,builder: (_) => _buildDialog(context, _itemForMessage(message)),).then((bool shouldNavigate) {if (shouldNavigate == true) {_navigateToItemDetail(message);}});}
//WIDGET WHICH IS GOING TO BE CALLED IN THE ABOVE DIALOGUE
Widget _buildDialog(BuildContext context, Item item) {return new AlertDialog(content: new Text("Item ${item.itemId} has been updated"),actions: <Widget>[new FlatButton(child: const Text('CLOSE'),onPressed: () {Navigator.pop(context, false);},),new FlatButton(child: const Text('SHOW'),onPressed: () {Navigator.pop(context, true);},),]);}
@override
void initState() {
super.initState();
_firebaseMessaging.configure(
onLaunch: (Map<String, dynamic> message) async { _navigateToItemDetail(message);},
onResume: (Map<String, dynamic> message) async { _navigateToItemDetail(message);},
onMessage: (Map<String, dynamic> message) async {_showItemDialog(message);},);
//GETTING TOKEN FOR TESTING MANUALY
_firebaseMessaging.getToken().then((String token) {assert(token != null);setState(() {_homeScreenText = "Push Messaging token: $token";});print(_homeScreenText);});}
@override
Widget build(BuildContext context) {
return new Scaffold(
appBar: new AppBar( title: const Text('Push Messaging Demo'),),
body: new Material(
child: new Column(
children: <Widget>[
new Center(
child: new Text(_homeScreenText),
new Row(children: <Widget>[
new Expanded(
child: new TextField(
controller: _topicController,
onChanged: (String v) {
setState(() {
_topicButtonsDisabled = v.isEmpty;
new FlatButton(
child: const Text("subscribe"),
onPressed: _topicButtonsDisabled
? null
: () {
_firebaseMessaging
.subscribeToTopic(_topicController.text);
_clearTopicText();
new FlatButton(child: const Text("unsubscribe"),
onPressed: _topicButtonsDisabled? null: () { _firebaseMessaging.unsubscribeFromTopic(_topicController.text);
_clearTopicText();},),
])],),));}}
//THREE DUMMY CLASSES FOR TESTING PURPOSE
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
//PAGE1
class Nexpage1 extends StatefulWidget { @override _Nexpage1State createState() => _Nexpage1State();}
class _Nexpage1State extends State<Nexpage1> { @override Widget build(BuildContext context) { return Scaffold(body: new Center(child: new Text(" Page1"),));}}
//PAGE2
class Nexpage2 extends StatefulWidget { @override _Nexpage2State createState() => _Nexpage2State();}
class _Nexpage2State extends State<Nexpage2> { @override Widget build(BuildContext context) { return Scaffold( body: Center(child: new Text("2pending"),) ); }}
//PAGE3
class Nexpage3 extends StatefulWidget { @override _Nexpage3State createState() => _Nexpage3State();}
class _Nexpage3State extends State<Nexpage3> { @override Widget build(BuildContext context) { return Scaffold( body: Center(child: new Text("3connected"),) ); }}
//THIS IS THE CLASS WHICH IS USED TO PARSE THE INFORMATION
class Item {
Item({this.itemId});
final String itemId;
StreamController<Item> _controller = new StreamController<Item>.broadcast();
Stream<Item> get onChanged => _controller.stream;
String _status;
String get status => _status;
set status(String value) {
_status = value;
_controller.add(this);
static final Map<String, Route<Null>> routes = <String, Route<Null>>{};
Route<Null> get route {
final String routeName = '/detail/$itemId';
return routes.putIfAbsent(
routeName,
() => new MaterialPageRoute<Null>(
settings: new RouteSettings(name: routeName),
builder: (BuildContext context) => new Nexpage3(),
