Flutter 平台通道将多数据传递给 windows 功能

我正在用Windows VISUAL Studio 2022测试Platform-Channels.

我可以在获得电池电池值的同时，从Ffltter用户界面传递单个值，但我想要将Ffltter中的多个数据发送到Windows代码. 以下是我的测试代码，我将遵循Fighting教程:

class _MyHomePageState extends State<MyHomePage> {
  static const MethodChannel platform =
      MethodChannel('samples.flutter.dev/battery');

  String _batteryLevel = 'Unknown battery level.';
  int value = 100;
  Future<void> _getBatteryLevel(int fluval) async {
    String batteryLevel;
    try {
      final int result = await platform.invokeMethod('getBatteryLevel', fluval);
      batteryLevel = 'Battery level at $result % .';
    } on PlatformException catch (e) {
      batteryLevel = "Failed to get battery level: '${e.message}'.";
    }
    setState(() {
      _batteryLevel = batteryLevel;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Material(
      child: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.spaceEvenly,
          children: [
            ElevatedButton(
              onPressed: () {
                _getBatteryLevel(100);
              },
              child: const Text('Get Battery Level'),
            ),
            Text(_batteryLevel),
          ],
        ),
      ),
    );
  }
}

和窗边:

void initMethodChannel(flutter::FlutterEngine* flutter_instance) {
    const static std::string channel_name("samples.flutter.dev/battery");
    auto channel =
        std::make_unique<flutter::MethodChannel<>>(
            flutter_instance->messenger(), channel_name,
            &flutter::StandardMethodCodec::GetInstance());
    channel->SetMethodCallHandler(
        [](const flutter::MethodCall<>& call,
            std::unique_ptr<flutter::MethodResult<flutter::EncodableValue>> result) {

                // cheack method name called from dart
                if (call.method_name().compare("getBatteryLevel") == 0) {
                    int battery_level = GetBatteryLevel();
                    const auto* flu_value = std::get_if<int>(call.arguments());
                    std::cout << typeid(flu_value).name() << std::endl;

                    if (!flu_value) {
                        result->Error("Missing required type parameter","Expected int");
                    }
                    std::cout << "From Flutter: " << *flu_value << std::endl;

                    if (battery_level != -1) {
                        result->Success(battery_level);
                    }
                    else {
                        result->Error("UNAVAILABLE", "Battery level not available.");
                    }
                }
                else {
                    result->NotImplemented();
                }
        });
}

如果我想像这样发送多个数据:

Future<void> _getBatteryLevel(int fluval, int data2,...,...) ...

当调用一次invkeMethod时，我应该如何处理或解析这两个值:Fluval和Data2？

有什么我可以参考的例子吗？或者是WindowsUI设计的小贴士？

我试着搜索，但大多数答案是针对Android或iOS应用程序的，Android的答案是使用call.argument("value")，你可以 Select 特定的数据值来使用，但Windows只有call.arguments();个函数调用，我不知道如何获得我想要的特定数据.

============================================================ [更新] 从@Richard Tips and Example， 我做了一个测试，它起作用了，谢谢你，理查德！

下面是Flutter 用户界面示例代码:(在Stateful Widget State类中)，Fluval=100，flval2=87

  String _getBackV1 = 'Unknown Value 1.';
  String _getBackV2 = 'Unknown Value 2.';
  int value = 100;
  Future<void> _testMapPassValue(int fluval, int fluval2) async {
    String backValue1, backValue2;
    try {
      final Map<String, dynamic>? getReply = await platform
          .invokeMapMethod<String, dynamic>('testPass',
              <String, dynamic>{"fluval": fluval, "fluval2": fluval2});
      backValue1 = "Get Back Value 1 from windows: ${getReply!["fluval"]}";
      backValue2 = "Get Back Value 2 from windows: ${getReply!["fluval2"]}";
    } on PlatformException catch (e) {
      backValue1 = "Failed to get Value 1: '${e.message}'.";
      backValue2 = "Failed to get Value 2: '${e.message}'.";
    }
    setState(() {
      _getBackV1 = backValue1;
      _getBackV2 = backValue2;
    });
  }

在Windows端的示例代码中:

using flutter::EncodableList;
using flutter::EncodableMap;
using flutter::EncodableValue;
constexpr char testMapPassValue[] = "testPass";

constexpr char passKey1[] = "fluval";
constexpr char passKey2[] = "fluval2";

方法调用处理程序:

if (call.method_name().compare(testMapPassValue) == 0) {
  const auto* getArguments_flu = std::get_if<flutter::EncodableMap>(call.arguments());
  assert(getArguments_flu);
  return Flu_2_Win_MethodHandler(*getArguments_flu, std::move(result));
}

void Flu_2_Win_MethodHandler(
    const EncodableMap& args, std::unique_ptr<flutter::MethodResult<>> result) {
    // Parse enableAudio argument.
    int wins2fluValue1;
    int wins2fluValue2;
    EncodableMap win2fluMap;

    const auto* flu2winsValue1 =
        std::get_if<int>(ValueOrNull(args, passKey1));
    if (!flu2winsValue1) {
        return result->Error("argument_error",
            std::string(passKey1) + " argument missing");
    }
    wins2fluValue1 = *flu2winsValue1;
    std::cout << "From Flutter value1: " << *flu2winsValue1 << std::endl;
    wins2fluValue1 = wins2fluValue1 + 10;
    std::cout << "After calculate value1: " << wins2fluValue1 << std::endl;

    const auto* flu2winsValue2 =
        std::get_if<int>(ValueOrNull(args, passKey2));
    if (!flu2winsValue2) {
        return result->Error("argument_error",
            std::string(passKey2) + " argument missing");
    }
    wins2fluValue2 = *flu2winsValue2;
    std::cout << "From Flutter value1: " << *flu2winsValue2 << std::endl;
    wins2fluValue2 = wins2fluValue2 + 20;
    std::cout << "After calculate value2: " << wins2fluValue2 << std::endl;

    win2fluMap.insert(std::pair<std::string, int>("fluval", wins2fluValue1));
    win2fluMap.insert(std::pair<std::string, int>("fluval2", wins2fluValue2));
    
    return result->Success(std::move(EncodableValue(win2fluMap)));
}

最后的结果是:

谢谢!