//2.本地kotlin代码
class MainActivity : FlutterActivity() {

    companion object {
        const val FLUTTER_ANDROID_LOG_CHANNEL = "flutter_android_log"
    }

    override fun configureFlutterEngine(flutterEngine: FlutterEngine) {
        super.configureFlutterEngine(flutterEngine)
        GeneratedPluginRegistrant.registerWith(flutterEngine)
        MethodChannel(flutterEngine.dartExecutor.binaryMessenger, FLUTTER_ANDROID_LOG_CHANNEL)
                .setMethodCallHandler { call, result ->
                    var tag: String = call.argument("tag") ?: "LogUtils"
                    var message: String = call.argument("msg") ?: "unknown log message"
                    when (call.method) {
                        "logD" -> Log.d(tag, message)
                        "logE" -> Log.e(tag, message)
                    }
                    result.success(null)
                }
    }
}

//2.flutter的dart代码 下划线_表示私有变量
import ‘package:flutter/services.dart‘;
class LogUtils {
  static const String _tag = "LogUtils";
  static const _perform = const MethodChannel("flutter_android_log");

  static void d(String message) {
    _perform.invokeMethod("logD", {‘tag‘: _tag, ‘msg‘: message});
  }

  static void e(String message) {
    _perform.invokeMethod("logE", {‘tag‘: _tag, ‘msg‘: message});
  }
}

//3.调用

void _onPush() {
  LogUtils.e("_onPush press");
}

注意坑：与native方法有交互时，最好先Stop掉，再Start。热启动很多时候无效，坑死了。。。