我有一个网络调用要执行。但在此之前,我需要检查设备是否有互联网连接。
这是我目前为止所做的:
var connectivityResult = new Connectivity().checkConnectivity();// User defined class
if (connectivityResult == ConnectivityResult.mobile ||
connectivityResult == ConnectivityResult.wifi) {*/
this.getData();
} else {
neverSatisfied();
}
上述方法行不通。
使用connectivity_widget: ^0.1.7
添加附件:
dependencies:
connectivity_widget: ^0.1.7
添加代码:
ConnectivityWidget(
builder: (context, isOnline) => Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text(
"${isOnline ? 'Connected' : 'Offline'}",
style: TextStyle(
fontSize: 30,
color: isOnline ? Colors.green : Colors.red),
),
],
),
),
)
输出:
使用
dependencies:
connectivity: ^0.4.2
我们从资源处得到的是
import 'package:connectivity/connectivity.dart';
Future<bool> check() async {
var connectivityResult = await (Connectivity().checkConnectivity());
if (connectivityResult == ConnectivityResult.mobile) {
return true;
} else if (connectivityResult == ConnectivityResult.wifi) {
return true;
}
return false;
}
未来对我来说没什么问题,我们必须每次都实现它,比如:
check().then((intenet) {
if (intenet != null && intenet) {
// Internet Present Case
}
// No-Internet Case
});
所以为了解决这个问题,我创建了一个类,它接受一个布尔isNetworkPresent参数的函数,就像这样
methodName(bool isNetworkPresent){}
实用工具类是
import 'package:connectivity/connectivity.dart';
class NetworkCheck {
Future<bool> check() async {
var connectivityResult = await (Connectivity().checkConnectivity());
if (connectivityResult == ConnectivityResult.mobile) {
return true;
} else if (connectivityResult == ConnectivityResult.wifi) {
return true;
}
return false;
}
dynamic checkInternet(Function func) {
check().then((intenet) {
if (intenet != null && intenet) {
func(true);
}
else{
func(false);
}
});
}
}
并使用连接检查实用程序
fetchPrefrence(bool isNetworkPresent) {
if(isNetworkPresent){
}else{
}
}
我将使用这种语法
NetworkCheck networkCheck = new NetworkCheck();
networkCheck.checkInternet(fetchPrefrence)
基于这个答案https://stackoverflow.com/a/68436867/10761151
如果你使用dart零安全,你会得到一个错误,
因此,您可以将依赖项data_connection_checker: ^0.3.4更新为internet_connection_checker: ^0.0.1+2
你可以用这个代码
import 'dart:async';
import 'package:connectivity_plus/connectivity_plus.dart';
import 'package:internet_connection_checker/internet_connection_checker.dart';
class ConnectionUtil {
static final ConnectionUtil _singleton = new ConnectionUtil._internal();
ConnectionUtil._internal();
static ConnectionUtil getInstance() => _singleton;
bool hasConnection = false;
StreamController connectionChangeController = StreamController();
final Connectivity _connectivity = Connectivity();
void initialize() {
_connectivity.onConnectivityChanged.listen(_connectionChange);
}
void _connectionChange(ConnectivityResult result) {
_hasInternetInternetConnection();
}
Stream get connectionChange => connectionChangeController.stream;
Future<bool> _hasInternetInternetConnection() async {
bool previousConnection = hasConnection;
var connectivityResult = await (Connectivity().checkConnectivity());
if (connectivityResult == ConnectivityResult.mobile || connectivityResult == ConnectivityResult.wifi) {
// this is the different
if (await InternetConnectionChecker().hasConnection) {
hasConnection = true;
} else {
hasConnection = false;
}
} else {
hasConnection = false;
}
if (previousConnection != hasConnection) {
connectionChangeController.add(hasConnection);
}
return hasConnection;
}
}
在有状态小部件上可以实现此代码
bool hasInterNetConnection = false;
@override
initState() {
ConnectionUtil connectionStatus = ConnectionUtil.getInstance();
connectionStatus.initialize();
connectionStatus.connectionChange.listen(connectionChanged);
super.initState();
}
void connectionChanged(dynamic hasConnection) {
setState(() {
hasInterNetConnection = hasConnection;
});
}
import 'dart:async';
import 'dart:io';
import 'package:flutter/material.dart';
import 'package:app_settings/app_settings.dart';
import 'package:connectivity/connectivity.dart';
class InternetConnect extends StatefulWidget {
@override
InternetConnectState createState() => InternetConnectState();
}
class InternetConnectState extends State<InternetConnect> {
ConnectivityResult previous;
bool dialogshown = false;
StreamSubscription connectivitySubscription;
Future<bool> checkinternet() async {
try {
final result = await InternetAddress.lookup('google.com');
if (result.isNotEmpty && result[0].rawAddress.isNotEmpty) {
return Future.value(true);
}
} on SocketException catch (_) {
return Future.value(false);
}
}
void checkInternetConnect(BuildContext context) {
connectivitySubscription = Connectivity()
.onConnectivityChanged
.listen((ConnectivityResult connresult) {
if (connresult == ConnectivityResult.none) {
dialogshown = true;
showDialog(
context: context, barrierDismissible: false, child: alertDialog());
} else if (previous == ConnectivityResult.none) {
checkinternet().then((result) {
if (result == true) {
if (dialogshown == true) {
dialogshown = false;
Navigator.pop(context);
}
}
});
}
previous = connresult;
});
}
AlertDialog alertDialog() {
return AlertDialog(
title: Text('ERROR'),
content: Text("No Internet Detected."),
actions: <Widget>[
FlatButton(
// method to exit application programitacally
onPressed: () {
AppSettings.openWIFISettings();
},
child: Text("Settings"),
),
],
);
}
@override
Widget build(BuildContext context) {
return Container();
}
}
and you can use this method in init of any class
@override
void initState() {
// TODO: implement initState
InternetConnectState().checkInternetConnect(context);
super.initState();
}