如何将消息从 Flutter 传递到 Native？

Question

如果需要与特定 API / 硬件组件交互，您将如何将信息从 Flutter 传回 Android/Native 代码？

是否有任何事件通道可以以其他方式或类似于回调的方式发送信息？

platform_channel documentation points out "method calls can also be sent in the reverse direction, with the platform acting as client to methods implemented in Dart. A concrete example of this is the quick_actions plugin。”我没有看到本机端在这种情况下如何从 Flutter 接收消息。
看来BasicMessageChannel的send()方法可以用来发送"the specified message to the platform plugins on this channel"。谁能提供一个简单的实现示例？

Answer 1

是的，flutter 确实有一个 EventChannel class，这正是您要找的。

Here 是演示如何实现 MethodChannel 和 EventChannel 的示例。和 this 中篇文章展示了如何在 flutter 中实现 EventChannel。

希望对您有所帮助！

Answer 2

这是一个简单的实现展示：

将字符串值从 flutter 传递到 Android 代码
从 Android 代码返回响应以进行 flutter

代码基于以下示例：https://flutter.io/platform-channels/#codec

1.Passing 字符串值 "text" :

String text = "whatever";

Future<Null> _getBatteryLevel(text) async {
String batteryLevel;
try {
  final String result = await platform.invokeMethod('getBatteryLevel',{"text":text}); 
  batteryLevel = 'Battery level at $result % .';
} on PlatformException catch (e) {
  batteryLevel = "Failed to get battery level: '${e.message}'.";
}

setState(() {
  _batteryLevel = batteryLevel;
});

}

2.Getting 返回响应 "batterylevel" 在 RandomFunction() 之后；

 public void onMethodCall(MethodCall call, MethodChannel.Result result) {
                    if (call.method.equals("getBatteryLevel")) {

                        text = call.argument("text");
                        String batteryLevel = RandomFunction(text);

                        if (batteryLevel != null) {
                            result.success(batteryLevel);
                        } else {
                            result.error("UNAVAILABLE", "Battery level not available.", null);
                        }
                    } else {
                        result.notImplemented();
                    }
                }

希望对您有所帮助！

Answer 3

Objective C

call.arguments[@"parameter"]

Android

call.argument("parameter");

Answer 4

对于swift

    guard let args = call.arguments as? [String : Any] else {return}
    let phoneNumber = args["contactNumber"] as! String
    let originalMessage = args["message"] as! String

Answer 5

如果有人想用invoke方法分享从native到flutter的数据按照这个：

main.dart

Future<dynamic> handlePlatformChannelMethods() async {
  platform.setMethodCallHandler((methodCall) async {
   if (methodCall.method == "nativeToFlutter") {
     String text = methodCall.arguments;
     List<String> result = text.split(' ');
     String user = result[0];
     String message = result[1];
    }
   }
  }

MainActivity.java

 nativeToFlutter(text1:String?,text2:String?){
 MethodChannel(flutterEngine!!.dartExecutor.binaryMessenger, 
  CHANNEL.invokeMethod("nativeToFlutter",text1+" "+text2);
 }

如何将消息从 Flutter 传递到 Native？

How to pass a message from Flutter to Native?

android

ios

dart

flutter