我正在使用Flutter制作一款命令和控制应用程序，并遇到了一个奇怪的问题。应用程序的主状态页面显示了一个有状态小部件列表，每个小部件都拥有一个WebSocket连接，该连接从连接的机器人平台中流式传输状态数据。当机器人自身被硬编码时，这种方式很有效。然而，现在我正在通过条形码扫描动态添加它们，只有第一个小部件显示状态。
进一步调查发现，这是由于仅为列表中的第一个小部件创建了状态。随后添加的小部件成功构建，但未获得状态。这意味着除第一个添加的小部件外，createState未被调用。我检查了小部件是否确实被添加到列表中，并且它们各自具有唯一的哈希代码。此外，IOWebSocketChannel具有唯一的哈希代码，所有小部件数据对于列表中的不同元素都是正确且唯一的。
有任何想法是什么导致了这个问题？
HomePageState的代码：
进一步调查发现，这是由于仅为列表中的第一个小部件创建了状态。随后添加的小部件成功构建，但未获得状态。这意味着除第一个添加的小部件外，createState未被调用。我检查了小部件是否确实被添加到列表中，并且它们各自具有唯一的哈希代码。此外，IOWebSocketChannel具有唯一的哈希代码，所有小部件数据对于列表中的不同元素都是正确且唯一的。
有任何想法是什么导致了这个问题？
HomePageState的代码：
class HomePageState extends State<HomePage> {
String submittedString = "";
StateContainerState container;
List<RobotSummary> robotList = [];
List<String> robotIps = [];
final GlobalKey<ScaffoldState> scaffoldKey = new GlobalKey<ScaffoldState>();
void addRobotToList(String ipAddress) {
var channel = new IOWebSocketChannel.connect('ws://' + container.slsData.slsIpAddress + ':' + container.slsData.wsPort);
channel.sink.add("http://" + ipAddress);
var newConnection = new RobotSummary(key: new UniqueKey(), channel: channel, ipAddress: ipAddress, state: -1, fullAddress: 'http://' + container.slsData.slsIpAddress + ':' + container.slsData.wsPort,);
scaffoldKey.currentState.showSnackBar(new SnackBar(
content: new Text("Adding robot..."), duration: Duration(seconds: 2),));
setState(() {
robotList.add(newConnection);
robotIps.add(ipAddress);
submittedString = ipAddress;
});
}
void _onSubmit(String val) {
// Determine the scan data that was entered
if(Validator.isIP(val)) {
if(ModalRoute.of(context).settings.name == '/') {
if (!robotIps.contains(val)) {
addRobotToList(val);
}
else {
scaffoldKey.currentState.showSnackBar(new SnackBar(
content: new Text("Robot already added..."), duration: Duration(seconds: 5),));
}
}
else {
setState(() {
_showSnackbar("Robot scanned. Go to page?", '/');
});
}
}
else if(Validator.isSlotId(val)) {
setState(() {
_showSnackbar("Slot scanned. Go to page?", '/slots');
});
}
else if(Validator.isUPC(val)) {
setState(() {
_showSnackbar("Product scanned. Go to page?", '/products');
});
}
else if (Validator.isToteId(val)) {
}
}
@override
Widget build(BuildContext context) {
container = StateContainer.of(context);
return new Scaffold (
key: scaffoldKey,
drawer: Drawer(
child: CategoryRoute(),
),
appBar: AppBar(
title: Text(widget.topText),
),
bottomNavigationBar: BottomAppBar(
child: new Row(
mainAxisSize: MainAxisSize.max,
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: <Widget>[
IconButton(icon: Icon(Icons.camera_alt), onPressed: scan,),
IconButton(icon: Icon(Icons.search), onPressed: _showModalSheet,),
],
),
),
body: robotList.length > 0 ? ListView(children: robotList) : Center(child: Text("Please scan a robot.", style: TextStyle(fontSize: 24.0, color: Colors.blue),),),
);
}
void _showModalSheet() {
showModalBottomSheet(
context: context,
builder: (builder) {
return _searchBar(context);
});
}
void _showSnackbar(String message, String route) {
scaffoldKey.currentState.showSnackBar(new SnackBar(
content: new Text(message),
action: SnackBarAction(
label: 'Go?',
onPressed: () {
if (route == '/') {
Navigator.popUntil(context,ModalRoute.withName('/'));
}
else {
Navigator.of(context).pushNamed(route);
}
},),
duration: Duration(seconds: 5),));
}
Widget _searchBar(BuildContext context) {
return new Scaffold(
body: Container(
height: 75.0,
color: iam_blue,
child: Center(
child: TextField(
style: TextStyle (color: Colors.white, fontSize: 18.0),
autofocus: true,
keyboardType: TextInputType.number,
onSubmitted: (String submittedStr) {
Navigator.pop(context);
_onSubmit(submittedStr);
},
decoration: new InputDecoration(
border: InputBorder.none,
hintText: 'Scan a tote, robot, UPC, or slot',
hintStyle: TextStyle(color: Colors.white70),
icon: const Icon(Icons.search, color: Colors.white70,)),
),
)));
}
Future scan() async {
try {
String barcode = await BarcodeScanner.scan();
setState(() => this._onSubmit(barcode));
} on PlatformException catch (e) {
if (e.code == BarcodeScanner.CameraAccessDenied) {
setState(() {
print('The user did not grant the camera permission!');
});
} else {
setState(() => print('Unknown error: $e'));
}
} on FormatException{
setState(() => print('null (User returned using the "back"-button before scanning anything. Result)'));
} catch (e) {
setState(() => print('Unknown error: $e'));
}
}
}
RobotSummary类的代码片段：
import 'package:flutter/material.dart';
import 'package:meta/meta.dart';
import 'package:test_app/genericStateSummary_static.dart';
import 'dart:convert';
import 'package:web_socket_channel/web_socket_channel.dart';
import 'package:test_app/StateDecodeJsonFull.dart';
import 'dart:async';
import 'package:test_app/dataValidation.dart';
class RobotSummary extends StatefulWidget {
final String ipAddress;
final String _port = '5000';
final int state;
final String fullAddress;
final WebSocketChannel channel;
RobotSummary({
Key key,
@required this.ipAddress,
@required this.channel,
this.state = -1,
this.fullAddress = "http://10.1.10.200:5000",
}) : assert(Validator.isIP(ipAddress)),
super(key: key);
@override
_RobotSummaryState createState() => new _RobotSummaryState();
}
class _RobotSummaryState extends State<RobotSummary> {
StreamController<StateDecodeJsonFull> streamController;
@override
void initState() {
super.initState();
streamController = StreamController.broadcast();
}
@override
Widget build(BuildContext context) {
return new Padding(
padding: const EdgeInsets.all(20.0),
child: new StreamBuilder(
stream: widget.channel.stream,
builder: (context, snapshot) {
//streamController.sink.add('{"autonomyControllerState" : 3, "pickCurrentListName" : "69152", "plannerExecutionProgress" : 82, "pickUpcCode" : "00814638", "robotName" : "Adam"}');
return getStateWidget(snapshot);
},
),
);
}
@override
void dispose() {
streamController.sink.close();
super.dispose();
}
}
Scaffold body更改为ListView(children: roboList)，它会工作吗？或者如果在setState内部重新创建列表，创建一个新的列表并从旧列表中addAll呢？ - Jacob Phillips