Flutter和原生代码的通信

1.Flutter和原生代码的通信

我们只用Flutter实现了一个页面，现有的大量逻辑都是用Java实现，在运行时会有许多场景必须使用原生应用中的逻辑和功能，例如网络请求，我们统一的网络库会在每个网络请求中添加许多通用参数，也会负责成功率等指标的监控，还有异常上报，我们需要在捕获到关键异常时将其堆栈和环境信息上报到服务器。这些功能不太可能立即使用Dart实现一套出来，所以我们需要使用Dart提供的Platform Channel功能来实现Dart→Java之间的互相调用。

以网络请求为例，我们在Dart中定义一个MethodChannel对象：

import 'dart:async';
import 'package:flutter/services.dart';
const MethodChannel _channel = const MethodChannel('com.kuaiX.happy/getVersion');
Future<Map<String, dynamic>> post(String path, [Map<String, dynamic> form]) async {
  return _channel.invokeMethod("getVersion", {'path': path, 'body': form}).then((result) {
    return new Map<String, dynamic>.from(result);
  }).catchError((_) => null);
}

然后在Java端实现相同名称的MethodChannel：

public class FlutterNetworkPlugin implements MethodChannel.MethodCallHandler {

    private static final String CHANNEL_NAME = "com.kuaiX.happy/getVersion";

    @Override
    public void onMethodCall(MethodCall methodCall, final MethodChannel.Result result) {
        switch (methodCall.method) {
            case "getVersion":
                RetrofitManager.performRequest(post((String) methodCall.argument("path"), (Map) methodCall.argument("body")),
                        new DefaultSubscriber<Map>() {
                            @Override
                            public void onError(Throwable e) {
                                result.error(e.getClass().getCanonicalName(), e.getMessage(), null);
                            }

                            @Override
                            public void onNext(Map stringBaseResponse) {
                                result.success(stringBaseResponse);
                            }
                        }, tag);
                break;

            default:
                result.notImplemented();
                break;
        }
    }
}

在Flutter页面中注册后，调用post方法就可以调用对应的Java实现：

loadData: (callback) async {
    Map<String, dynamic> data = await getVersion("version/level");
    if (data == null) {
      callback(false);
      return;
    }
    _data = AllCategoryResponse.fromJson(data);
    if (_data == null || _data.code != 0) {
      callback(false);
      return;
    }
    callback(true);
  }),

2.Demo实现 -> 从原生传数据到FLutter端

class AppUtils : FlutterPlugin, MethodCallHandler {

  private var channel: MethodChannel? = null
    private var sContext: Context? = null
    private val TAG = "AppUtils"
          override fun onAttachedToEngine(binding: FlutterPlugin.FlutterPluginBinding) {
        channel = MethodChannel(binding.getBinaryMessenger(), TAG)
        channel?.setMethodCallHandler(this)
        sContext = binding.getApplicationContext()
    }

    override fun onDetachedFromEngine(binding: FlutterPlugin.FlutterPluginBinding) {
        channel?.setMethodCallHandler(null);
    }
    override fun onMethodCall(call: MethodCall, result: MethodChannel.Result) {
        if (sContext == null) {
            throw RuntimeException(" context is null  please call setContext(this) in Application.onCreate()")
        }
        if (call.method.equals("getPlatformVersion")) {
            result.success("Android " + android.os.Build.VERSION.RELEASE);
        } else if (call.method.equals("getSmid")) {

        } else {
            result.notImplemented();
        }
    }
}

Flutter端实现

class HomeLogic extends GetMaterialController {

static const MethodChannel channel = const MethodChannel('AppUtils');

  static Future<String?> getPlatformVersion() async {
    final String? version = await channel.invokeMethod('getPlatformVersion');
    return version;
  }

	@override
  onInit(){
		String? temp = await getPlatformVersion();
    print("12i3904201" + temp.toString());
  }
}