在Flutter中,我想监听websocket断开事件,该如何实现?当应用程序进入后台时,websocket连接将会断开,我仍然没有找到让它在后台持续运行的方法(有人有解决方案吗?),因此我必须检测是否丢失了websocket连接,以便在失去连接时重新连接。如果有人知道如何实现,请帮忙。
onDone
回调来判断 WebSocket 是否关闭。请参考以下示例: _channel = IOWebSocketChannel.connect(
'ws://yourserver.com:port',
);
///
/// Start listening to new notifications / messages
///
_channel.stream.listen(
(dynamic message) {
debugPrint('message $message');
},
onDone: () {
debugPrint('ws channel closed');
},
onError: (error) {
debugPrint('ws error $error');
},
);
希望这可以帮助你。
ws.pingInterval = const Duration(seconds: 5);
应该调用onDone。
基本的乒乓足以。
其他关于SO和网络的答案表明,你不能仅仅将套接字保持在后台(这似乎是合理的,因为你会保持打开可能影响电池寿命的网络连接)。根据您的用例,您可能更好地查看推送通知或定期检查的内容。
WebSocketChannel channel = WebSocketChannel.connect(uri );
Stream stream = channel.stream;
stream.listen((event) {
print('Event from Stream: $event');
},onError: (e){
Future.delayed(Duration(seconds: 10)).then((value) {
connectAndListen();
},);
},
onDone: (() {
Future.delayed(Duration(seconds: 10)).then((value) {
connectAndListen();
},);
})
);
我建议您使用这个跨平台的WebSocket包https://pub.dev/packages/websocket_universal,在那里您甚至可以跟踪所有发生的WS事件(如果需要,还有内置的ping测量):
import 'package:websocket_universal/websocket_universal.dart';
/// Example works with Postman Echo server
void main() async {
/// Postman echo ws server (you can use your own server URI)
/// 'wss://ws.postman-echo.com/raw'
/// For local server it could look like 'ws://127.0.0.1:42627/websocket'
const websocketConnectionUri = 'wss://ws.postman-echo.com/raw';
const textMessageToServer = 'Hello server!';
const connectionOptions = SocketConnectionOptions(
pingIntervalMs: 3000, // send Ping message every 3000 ms
timeoutConnectionMs: 4000, // connection fail timeout after 4000 ms
/// see ping/pong messages in [logEventStream] stream
skipPingMessages: false,
/// Set this attribute to `true` if do not need any ping/pong
/// messages and ping measurement. Default is `false`
pingRestrictionForce: false,
);
/// Example with simple text messages exchanges with server
/// (not recommended for applications)
/// [<String, String>] generic types mean that we receive [String] messages
/// after deserialization and send [String] messages to server.
final IMessageProcessor<String, String> textSocketProcessor =
SocketSimpleTextProcessor();
final textSocketHandler = IWebSocketHandler<String, String>.createClient(
websocketConnectionUri, // Postman echo ws server
textSocketProcessor,
connectionOptions: connectionOptions,
);
// Listening to webSocket status changes
textSocketHandler.socketHandlerStateStream.listen((stateEvent) {
// ignore: avoid_print
print('> status changed to ${stateEvent.status}');
});
// Listening to server responses:
textSocketHandler.incomingMessagesStream.listen((inMsg) {
// ignore: avoid_print
print('> webSocket got text message from server: "$inMsg" '
'[ping: ${textSocketHandler.pingDelayMs}]');
});
// Listening to debug events inside webSocket
textSocketHandler.logEventStream.listen((debugEvent) {
// ignore: avoid_print
print('> debug event: ${debugEvent.socketLogEventType}'
' [ping=${debugEvent.pingMs} ms]. Debug message=${debugEvent.message}');
});
// Listening to outgoing messages:
textSocketHandler.outgoingMessagesStream.listen((inMsg) {
// ignore: avoid_print
print('> webSocket sent text message to server: "$inMsg" '
'[ping: ${textSocketHandler.pingDelayMs}]');
});
// Connecting to server:
final isTextSocketConnected = await textSocketHandler.connect();
if (!isTextSocketConnected) {
// ignore: avoid_print
print('Connection to [$websocketConnectionUri] failed for some reason!');
return;
}
textSocketHandler.sendMessage(textMessageToServer);
await Future<void>.delayed(const Duration(seconds: 30));
// Disconnecting from server:
await textSocketHandler.disconnect('manual disconnect');
// Disposing webSocket:
textSocketHandler.close();
}