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。
我几乎读了所有的帖子,@dennmat的帖子对我最有用。虽然它对我没用,而且也过时了。我有更新颤振更新连接包(I。E connectivity_plus)和data_connection_checker(检查移动和wifi是否有实际的互联网连接)。
在这篇文章之后,你将能够连续监听互联网连接。
1. 添加依赖关系
A)连通性:^1.0.6
B) data_connection_checker: ^0.3.4
2. 处理所有连接的自定义类。
import 'dart:async';
import 'package:connectivity_plus/connectivity_plus.dart';
import 'package:data_connection_checker/data_connection_checker.dart';
class ConnectionUtil {
//This creates the single instance by calling the `_internal` constructor specified below
static final ConnectionUtil _singleton = new ConnectionUtil._internal();
ConnectionUtil._internal();
//This is what's used to retrieve the instance through the app
static ConnectionUtil getInstance() => _singleton;
//This tracks the current connection status
bool hasConnection = false;
//This is how we'll allow subscribing to connection changes
StreamController connectionChangeController = StreamController();
//flutter_connectivity
final Connectivity _connectivity = Connectivity();
void initialize() {
_connectivity.onConnectivityChanged.listen(_connectionChange);
}
//flutter_connectivity's listener
void _connectionChange(ConnectivityResult result) {
hasInternetInternetConnection();
}
Stream get connectionChange => connectionChangeController.stream;
Future<bool> hasInternetInternetConnection() async {
bool previousConnection = hasConnection;
var connectivityResult = await (Connectivity().checkConnectivity());
//Check if device is just connect with mobile network or wifi
if (connectivityResult == ConnectivityResult.mobile ||
connectivityResult == ConnectivityResult.wifi) {
//Check there is actual internet connection with a mobile network or wifi
if (await DataConnectionChecker().hasConnection) {
// Network data detected & internet connection confirmed.
hasConnection = true;
} else {
// Network data detected but no internet connection found.
hasConnection = false;
}
}
// device has no mobile network and wifi connection at all
else {
hasConnection = false;
}
// The connection status changed send out an update to all listeners
if (previousConnection != hasConnection) {
connectionChangeController.add(hasConnection);
}
return hasConnection;
}
}
检查任何地方的连接并倾听变化。
@override
initState() {
print('called');
//Create instance
ConnectionUtil connectionStatus = ConnectionUtil.getInstance();
//Initialize
connectionStatus.initialize();
//Listen for connection change
_connectionChangeStream = connectionStatus.connectionChange.listen((event) {
print(event);
});
super.initState();
}
切换飞行模式时检查日志。你应该得到有true和false值的日志。
注意:这将无法在flutter web工作,如果你想让它工作,请使用dio或http插件而不是data_connection_checker。
项目示例可以在这里找到。谢谢
对我来说,我只是在Firebase中创建一个数据,并使用未来构建器来等待数据。在这里,就像这样,你可以检查连接是否太慢,所以数据将被加载:
FutureBuilder(
future: _getImage(context),
builder: (context, snapshot) {
switch (snapshot.connectionState) {
case ConnectionState.none:
return Text('Press button to start.');
case ConnectionState.active:
case ConnectionState.waiting:
return Container(
height:
MediaQuery.of(context).size.height / 1.25,
width:
MediaQuery.of(context).size.width / 1.25,
child: Loading());
case ConnectionState.done:
if (snapshot.hasData) {
return snapshot.data;
} else {
return FlatButton(
onPressed: () {
Navigator.push(
context,
MaterialPageRoute(
builder: (context) =>
ProfilePage()));
},
child: Icon(
Icons.add_a_photo,
size: 50,
),
);
}
// You can reach your snapshot.data['url'] in here
}
return null;
},
),
我写了一个包来检查活跃的互联网连接和显示相应的小部件。
flutter_no_internet_widget
例子:
InternetWidget(
online: Text('Online'),
offline: Text('Offline),
);
根据网络状态,将显示适当的小部件。如果您有一个活跃的互联网连接,一个在线小部件将显示。
所有重量级的工作都由包完成,您所要做的就是提供在线和离线小部件。您还可以提供一个加载小部件和查找URL。
欢迎讨论、提交意见书或提出建议。