我在 Flutter 应用程序中使用 ESP32 作为 BLE 设备时遇到了问题（我使用 Flutter_Blue_Plus 包）。我希望能够读取 ESP 发送的信息并同时写入另一个特征。 但是当我读完之后开始写作时，我会遇到很大的延迟，这是我想避免的。
我的问题如下：
我有一个 ESP32，配置为充当 BLE 设备。 我的 Flutter 应用程序通过 BLE 连接到该 ESP32，并尝试从特征中读取数据。 我开始通过应用程序将 JSON 文件写入 EPS32 上的另一个特征。 此时在 ESP32 接收数据之前我有一个很大的延迟，该延迟对应于读取的持续时间。 （如果没有开始读取，我就没有这个延迟）
（抱歉我的代码没有优化）
这是我的主页（其中包含已读内容）：
class HomeScreen extends StatefulWidget {
const HomeScreen({Key? key,}) : super(key: key);
@override
State<HomeScreen> createState() => _HomeScreenState();
}
class _HomeScreenState extends State<HomeScreen> {
int? _rssi;
int? _mtuSize;
BluetoothConnectionState _connectionState = BluetoothConnectionState.disconnected;
bool _isConnectingOrDisconnecting = false;
StreamSubscription<BluetoothConnectionState>? _connectionStateSubscription; // pb avec ça j'ai rajouter ? et enlever late mais erreur : _HomeScreenState.dispose failed to call super.dispose. psq pas init
StreamSubscription<bool>? _isConnectingOrDisconnectingSubscription;
StreamSubscription<int>? _mtuSubscription;
@override
void initState() {
super.initState();
if (BLEdevice?.remoteId.toString() != '00:00:00:00:00:00') {
_connectionStateSubscription = BLEdevice!.connectionState.listen((state) async {
_connectionState = state;
if (state == BluetoothConnectionState.connected) {
services = [];
}
if (state == BluetoothConnectionState.connected && _rssi == null) {
_rssi = await BLEdevice!.readRssi();
}
setState(() {});
});
_mtuSubscription = BLEdevice!.mtu.listen((value) {
_mtuSize = value;
setState(() {});
});
_isConnectingOrDisconnectingSubscription = BLEdevice!.isConnectingOrDisconnecting.listen((value) {
_isConnectingOrDisconnecting = value;
setState(() {});
});
getServices();
}
}
@override
void dispose() {
//print(BLEdevice?.remoteId.toString());
if (BLEdevice?.remoteId.toString() != '00:00:00:00:00:00') {
_connectionStateSubscription?.cancel();
_mtuSubscription?.cancel();
_isConnectingOrDisconnectingSubscription?.cancel();
super.dispose();
}
else
{
super.dispose();
}
}
bool get isConnected {
return _connectionState == BluetoothConnectionState.connected;
}
Future onConnectPressed() async {
try {
await BLEdevice!.connectAndUpdateStream();
} catch (e) {
print("Connect Error");
}
}
Future onDisconnectPressed() async {
try {
await BLEdevice!.disconnectAndUpdateStream();
BLEdevice = BluetoothDevice(remoteId: const DeviceIdentifier('00:00:00:00:00:00'));
MaterialPageRoute route = MaterialPageRoute(
builder: (context) => HomeScreen(), settings: const RouteSettings(name: '/ScanScreen'));
Navigator.of(context).push(route);
} catch (e) {
print("Disconnect Error");
}
}
Future getServices() async {
try {
services = await BLEdevice!.discoverServices();
} catch (e) {
print('Error: service discovery failed');
}
}
Widget buildCustomCard(BuildContext context, Icon icon, String text, double valueBLE, [Widget? destinationScreen]) // build custom card avec data
{
Size size = MediaQuery.of(context).size;
return FutureBuilder<void>(
future: getServices(),
builder: (BuildContext context, AsyncSnapshot<void> snapshot) {
if (snapshot.hasError)
{
return Text('Error line 166 home: ${snapshot.error}');
}
else
{
BluetoothCharacteristic? firstCharacteristic;
if (services.isNotEmpty && services[0].characteristics.isNotEmpty) {
firstCharacteristic = services[0].characteristics[0];
BluetoothUtil.readCharacteristic(firstCharacteristic,() => mounted? {setState(() {})}:null);
}
return firstCharacteristic != null
? CustomCard(
size: size,
title: text,
icon: icon,
valueBLE: valueBLE,
destinationScreen:destinationScreen
)
: CustomCard(
size: size,
title: text,
icon: icon,
valueBLE: valueBLE,
);
}
}
);
}
Widget buildCustomCardSelect(BuildContext context,Icon icon, String title, Color color, bool state, Function() onToggle) //build customCard avec bouton
{
Size size = MediaQuery.of(context).size;
return FutureBuilder<void>(
future: getServices(),
builder: (BuildContext context, AsyncSnapshot<void> snapshot) {
if (snapshot.connectionState == ConnectionState.waiting)
{
return CustomCardSelect(
size: size,
title: title,
icon: icon,
color: color,
state: state,
onToggle: onToggle,
);
}
else if (snapshot.hasError)
{
return Text('Error: ${snapshot.error}');
}
else
{
BluetoothCharacteristic? writeCharacteristic;
if (services.isNotEmpty && services[0].characteristics.isNotEmpty) {
writeCharacteristic = services[0].characteristics[1];
}
return writeCharacteristic != null
? CustomCardSelect(
size: size,
title: title,
icon: icon,
color: color,
state: state,
onToggle: onToggle,
characteristic: writeCharacteristic
):CustomCardSelect(
size: size,
title: title,
icon: icon,
color: color,
state: state,
onToggle: onToggle,
);
}
}
);
}
@override
Widget build(BuildContext context, ) {
Size size = MediaQuery.of(context).size; //Size(400, 400);// !!!! ???
return Scaffold(
backgroundColor: WhiteColor,
body: SafeArea(
child: SingleChildScrollView(
child: Padding(
padding: EdgeInsets.symmetric(horizontal: size.width * 0.01),
child: Column(
children: [
Container(
alignment: Alignment.centerLeft,
padding: EdgeInsets.only(left: size.width * 0.01),
child: Text(
"Data ",
style: TextStyle(fontSize: 23, fontWeight: FontWeight.bold, color: Color.fromARGB(255, 0, 0, 0)),
),
),
SizedBox(height: size.height * 0.02),
Container(
padding: EdgeInsets.only(left: size.width * 0.02),
height: size.height * 0.20,
child: ListView(
clipBehavior: Clip.none,
scrollDirection: Axis.horizontal,
children:[
buildCustomCard(context, Icon(Icons.thermostat, size: 99 ,color: Colors.grey.shade400), "Température",currentTemp ,temperatureScreen()),
SizedBox(width: size.width * 0.05),
buildCustomCard(context, Icon(Icons.bubble_chart_outlined, size :55,color: Colors.grey.shade400), "TDS",currentTDS.toDouble()),
SizedBox(width: size.width * 0.05),
buildCustomCard(context, Icon(Icons.science_outlined, size: 99 ,color: Colors.grey.shade400), "PH",currentPH),
SizedBox(width: size.width * 0.05),
]
),
),
Padding(padding: EdgeInsets.only(bottom: size.width * 0.05)),
Container(
alignment: Alignment.centerLeft,
padding: EdgeInsets.only(left: size.width * 0.01),
child: const Text(
"Action ",
style: TextStyle(fontSize: 23, fontWeight: FontWeight.bold, color: Color.fromARGB(255, 0, 0, 0),),
),
),
SizedBox(height: size.height * 0.02),
// buildCustomCardSelect(context, const Icon(Icons.water_drop_outlined) ,"Pompe à air", Colors.blue.shade400),
Padding(padding: EdgeInsets.only(bottom: size.width * 0.05)),
buildCustomCardSelect(context, const Icon(Icons.light_mode) ,"Lumière", Colors.yellow.shade400, light, () => setState(() {light = !light;})),
Padding(padding: EdgeInsets.only(bottom: size.width * 0.07 )),
]
),
)
)
),
);
}
}
这是我的读写功能：
import 'dart:convert';
import 'package:flutter_blue_plus/flutter_blue_plus.dart';
import 'package:fishbotica/constants/data.dart';
class BluetoothUtil {
static Future<void> writeCharacteristic(
//< BluetoothCharacteristic? characteristic,
) async {
try {
await services[0].characteristics[1].write(
jsonToByte(),
withoutResponse: services[0].characteristics[1].properties.writeWithoutResponse,
);
} catch (e) {
print('error write ble : $e');
}
}
static List<int> jsonToByte() {
String jsonData =
json.encode(
{
"regulationTemp" :1// regulationTemp,
// "forceTemp" : forceTemp ? 1 : 0,
// "light" : setLight ? 1: 0,
}
);
List<int> dataByte = utf8.encode(jsonData);
return dataByte;
}
static Future<void> readCharacteristic(BluetoothCharacteristic characteristic, Function() onToggle) async {
String characteristicValue = "999";
double doubleValue = 999;
try {
final List<int> value = await characteristic.read();
print(value.toString());
// Convertir les données de la caractéristique en chaîne
String jsonString = String.fromCharCodes(value );
Map<String, dynamic> jsonData = json.decode(jsonString);
currentTemp = double.parse(jsonData["temp"]);
currentPH = jsonData["pH"];
currentTDS = jsonData["TDS"];
onToggle();
} catch (e) {
print('Erreur lors de la lecture de la caractéristique : $e');
}
}
}
这是我管理写入并在主页上启动的小部件：
class CustomCardSelect extends StatefulWidget {
Size size;
String title;
Icon icon;
Color color;
bool state;
Function() onToggle;
BluetoothCharacteristic? characteristic;
CustomCardSelect(
{super.key,
required this.size,
required this.title,
required this.icon,
required this.color,
required this.state,
required this.onToggle,
this.characteristic,
});
@override
State<CustomCardSelect> createState() => _CustomCardSelectState();
}
class _CustomCardSelectState extends State<CustomCardSelect>
with SingleTickerProviderStateMixin {
// BLE
late bool isChecked;
//bool temp = false;
BluetoothCharacteristic? get c => widget.characteristic;
@override
void initState() {
super.initState();
isChecked = widget.state;
}
@override
void dispose() {
super.dispose();
}
void setIconColor() {
setState(() {
if (!isChecked) {
widget.icon = Icon(widget.icon.icon, size: 35, color: Colors.grey.shade400);
} else {
widget.icon = Icon(widget.icon.icon, size: 35, color: widget.color);
}
});
}
@override
Widget build(BuildContext context) {
return
Container(
height: widget.size.height * 0.14,
width: widget.size.width * 0.9,
decoration: BoxDecoration(
color: KCustomCard,
borderRadius: BorderRadius.circular(20),
border: Border.all(color: Colors.grey.shade400),
boxShadow: const [
BoxShadow(
color: Colors.black12,
offset: Offset(3, 3),
blurRadius: 8,
),
BoxShadow(
color: Colors.white,
offset: Offset(-3, -3),
blurRadius: 8,
),
],
),
child: Padding(
padding: EdgeInsets.all(15),
child:Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: [
Row(
mainAxisAlignment: MainAxisAlignment.spaceAround,
children:
[
Icon(widget.icon.icon, color: Colors.black, size: 35),
Padding(padding: EdgeInsets.only(left: 15)),
Text(widget.title, style: const TextStyle(fontSize: 19, fontWeight: FontWeight.bold, color: kBlueColor)) ,
]
),
Transform.scale(
scale: 1.1,
child: CupertinoSwitch(
value: isChecked,
onChanged: (isChecked) async {
this.isChecked = isChecked;
setState(() {
if (isChecked) {
setIconColor();
} else {
setIconColor();
}
});
await BluetoothUtil.writeCharacteristic();
widget.onToggle();
}
)
),
]
),
)
);
}
}
我还没有找到任何人谈论这个问题。 预先感谢您的回复;)
我想建议，为了避免等待蓝色被读取，您可以将蓝色读取条目保存在列表中，并在写入 json 文件之前监听此列表中的更改。