Android&Flutter混合開發初體驗

最近flutter不是一般的火呀，但對於一些成熟的產品來說，完全摒棄原有App的歷史沉澱，全面轉向Flutter是不現實的。因此使用Flutter去統一Android、iOS技術棧，把它作為已有原生App的擴充套件能力，通過有序推進來提升行動端的開發效率
（1）建立flutter模組，建立module後會AS會自動進行flutter的相關設定

（2）將FlutterActivity新增到AndroidManifest.xml

        <activity
            android:name="io.flutter.embedding.android.FlutterActivity"
            android:configChanges="orientation|keyboardHidden|keyboard|screenSize|locale|layoutDirection|fontScale|screenLayout|density|uiMode"
            android:hardwareAccelerated="true"
            android:theme="@style/FlutterTheme"
            android:windowSoftInputMode="adjustResize" />

（3）跳轉到flutter頁面

startActivity(FlutterActivity.withNewEngine().initialRoute("route").build(this))

（4）你也可以使用快取的FlutterEngine，可以減少載入延遲
在MyApplication中範例化一個FlutterEngine

class MyApplication : Application() {
    lateinit var flutterEngine: FlutterEngine
    override fun onCreate() {
        super.onCreate()
        flutterEngine = FlutterEngine(this)
        flutterEngine.dartExecutor.executeDartEntrypoint(DartExecutor.DartEntrypoint.createDefault())
        FlutterEngineCache.getInstance().put("my_engine_id", flutterEngine)
    }
}

然後在Activity中跳轉

        btn.setOnClickListener {
            startActivity(FlutterActivity.withCachedEngine("my_engine_id").build(this))
        }

注意：使用withCachedEngine()工廠方法時，請傳遞與快取所需的ID相同的ID FlutterEngine

設定快取引擎時也可以初始路由，修改MyApplication

        flutterEngine = FlutterEngine(this)
        flutterEngine.navigationChannel.setInitialRoute("route") //可以藉此攜帶一些字串資料，可傳遞到flutter頁面
        flutterEngine.dartExecutor.executeDartEntrypoint(DartExecutor.DartEntrypoint.createDefault())
        FlutterEngineCache.getInstance().put("my_engine_id", flutterEngine)

對應的dart

import 'dart:ui';
import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: _widgetForRoute(window.defaultRouteName),
    );
  }
}

//路由的選擇
Widget _widgetForRoute(String route) {
  switch (route) {
    case 'route':
      return MaterialApp(
        home: Scaffold(
          appBar: AppBar(
            title: Text('Flutter頁面'),
          ),
          body: Center(
            child: Text('行走的豬蹄',
                style: TextStyle(color: Colors.red),
                textDirection: TextDirection.ltr),
          ),
        ),
      );
    default:
      return Center(
        child: Text('Unknown route: $route',
            style: TextStyle(color: Colors.red),
            textDirection: TextDirection.ltr),
      );
  }
}