一、环境搭建
首先，须要开发者依照原生Android、iOS的搭建流程搭建好开发环境。而后，去Flutter官网下载最新的SDK，下载结束后解压到自定义目录即可。如果呈现下载问题，能够应用Flutter官网为中国开发者搭建的长期镜像。
export PUB_HOSTED_URL=https://pub.flutter-io.cnexport FLUTTER_STORAGE_BASE_URL=https://storage.flutter-io.cn为了方便使用命令行，还须要额定配置下环境变量。首先，应用vim命令关上终端。
vim ~/.bash_profile 而后，将如下代码增加到.bash_profile文件中，并应用source ~/.bash_profile命令使文件更改失效。
export PATH=/Users/mac/Flutter/flutter/bin:$PATH//刷新.bash_profilesource ~/.bash_profile实现上述操作之后，接下来应用flutter doctor命令查看环境是否正确，胜利会输入如下信息。
二、创立Flutter aar包
原生Android集成Flutter次要有两种形式，一种是创立flutter module，而后以原生module那样依赖；另一种形式是将flutter module打包成aar，而后在原生工程中依赖aar包，官网举荐aar的形式接入。
创立flutter aar有两种形式，一种是应用Android Studio进行生成，另一种是间接应用命令行。应用命令行创立flutter module如下：
flutter create -t module flutter_module而后，进入到flutter_module，执行flutter build aar命令生成aar包，如果没有任何出错，会在/flutter_module/.android/Flutter/build/outputs目录下生成对应的aar包，如下图。
build/host/outputs/repo└── com └── example └── my_flutter ├── flutter_release │ ├── 1.0 │ │ ├── flutter_release-1.0.aar │ │ ├── flutter_release-1.0.aar.md5 │ │ ├── flutter_release-1.0.aar.sha1 │ │ ├── flutter_release-1.0.pom │ │ ├── flutter_release-1.0.pom.md5 │ │ └── flutter_release-1.0.pom.sha1 │ ├── maven-metadata.xml │ ├── maven-metadata.xml.md5 │ └── maven-metadata.xml.sha1 ├── flutter_profile │ ├── ... └── flutter_debug └── ...当然，咱们也能够应用Android Studio来生成aar包。顺次抉择File -> New -> New Flutter Project -> Flutter Module生成Flutter module工程。
而后咱们顺次抉择build ->Flutter ->Build AAR即可生成aar包。
接下来，就是在原生Android工程中集成aar即可。
三、增加Flutter依赖
3.1 增加aar依赖
官网举荐形式
集成aar包的形式和集成一般的aar包的形式是一样大的。首先，在app的目录下新建libs文件夹 并在build.gradle中增加如下配置。
android { ...buildTypes { profile { initWith debug } } String storageUrl = System.env.FLUTTER_STORAGE_BASE_URL ?: "https://storage.googleapis.com" repositories { maven { url '/Users/mac/Flutter/module_flutter/build/host/outputs/repo' } maven { url "$storageUrl/download.flutter.io" } } }dependencies { debugImplementation 'com.xzh.module_flutter:flutter_debug:1.0' profileImplementation 'com.xzh.module_flutter:flutter_profile:1.0' releaseImplementation 'com.xzh.module_flutter:flutter_release:1.0' }本地Libs形式
当然，咱们也能够把生成的aar包拷贝到本地libs中，而后关上app/build.grade增加本地依赖，如下所示。
repositories { flatDir { dirs 'libs' }}dependencies { ... //增加本地依赖 implementation fileTree(dir: 'libs', include: ['*.jar']) implementation(name: 'flutter_debug-1.0', ext: 'aar') implementation 'io.flutter:flutter_embedding_debug:1.0.0-f0826da7ef2d301eb8f4ead91aaf026aa2b52881' implementation 'io.flutter:armeabi_v7a_debug:1.0.0-f0826da7ef2d301eb8f4ead91aaf026aa2b52881' implementation 'io.flutter:arm64_v8a_debug:1.0.0-f0826da7ef2d301eb8f4ead91aaf026aa2b52881' implementation 'io.flutter:x86_64_debug:1.0.0-f0826da7ef2d301eb8f4ead91aaf026aa2b52881'}io.flutter:flutter_embedding_debug来自哪里呢，其实是build/host/outputs/repo生成的时候flutter_release-1.0.pom文件中，
<groupId>com.example.flutter_library</groupId> <artifactId>flutter_release</artifactId> <version>1.0</version> <packaging>aar</packaging> <dependencies> <dependency> <groupId>io.flutter.plugins.sharedpreferences</groupId> <artifactId>shared_preferences_release</artifactId> <version>1.0</version> <scope>compile</scope> </dependency> <dependency> <groupId>io.flutter</groupId> <artifactId>flutter_embedding_release</artifactId> <version>1.0.0-626244a72c5d53cc6d00c840987f9059faed511a</version> <scope>compile</scope> </dependency>在拷贝的时候，留神咱们本地aar包的环境，它们是一一对应的。接下来，为了可能正确依赖，还须要在外层的build.gradle中增加如下依赖。
buildscript {repositories { google() jcenter() maven { url "http://download.flutter.io" //flutter依赖 } }dependencies { classpath 'com.android.tools.build:gradle:4.0.0' }}如果，原生Android工程应用的是组件化开发思路，通常是在某个module/lib下依赖，比方module_flutter进行增加。
在module_flutter build.gradle下配置 repositories { flatDir { dirs 'libs' // aar目录 } }在主App 下配置repositories {// 具体门路flatDir { dirs 'libs', '../module_flutter/libs' }}3.2 源码依赖
除了应用aar形式外， 咱们还能够应用flutter模块源码的形式进行依赖。首先，咱们在原生Android工程中创立一个module，如下图。
增加胜利后，零碎会默认在settings.gradle文件中生成如下代码。
include ':app' setBinding(new Binding([gradle: this])) evaluate(new File( settingsDir.parentFile, 'my_flutter/.android/include_flutter.groovy' )) 而后，在app/build.gradle文件中增加源码依赖。
dependencies { implementation project(':flutter')}3.3 应用 fat-aar 编译 aar
如果flutter 中引入了第三方的一些库，那么多个我的项目在应用flutter的时候就须要应用 fat-aar。首先，在 .android/build.gradle 中增加fat-aar 依赖。
dependencies { ... com.github.kezong:fat-aar:1.3.6 }而后,在 .android/Flutter/build.gradle 中增加如下 plugin 和依赖。
dependencies { testImplementation 'junit:junit:4.12' // 增加 flutter_embedding.jar debug embed "io.flutter:flutter_embedding_debug:1.0.0-eed171ff3538aa44f061f3768eec3a5908e8e852" // 增加 flutter_embedding.jar release embed "io.flutter:flutter_embedding_release:1.0.0-e1e6ced81d029258d449bdec2ba3cddca9c2ca0c" // 增加各个 cpu 版本 flutter.so embed "io.flutter:arm64_v8a_debug:1.0.0-eed171ff3538aa44f061f3768eec3a5908e8e852" embed "io.flutter:armeabi_v7a_debug:1.0.0-eed171ff3538aa44f061f3768eec3a5908e8e852" embed "io.flutter:x86_64_debug:1.0.0-eed171ff3538aa44f061f3768eec3a5908e8e852" embed "io.flutter:x86_debug:1.0.0-eed171ff3538aa44f061f3768eec3a5908e8e852"此时，如果咱们运行我的项目，可能会报一个Cannot fit requested classes in a single dex file的谬误。这是一个很古老的分包问题，意思是dex超过65k办法一个dex曾经装不下了须要个多个dex。解决的办法是，只须要在 app/build.gradle 增加multidex即可。
android { defaultConfig { ··· multiDexEnabled true }}dependencies { //androidx反对库的multidex库 implementation 'androidx.multidex:multidex:2.0.1'}五、跳转Flutter
5.1 启动FlutterActivity
集成Flutter之后，接下来咱们在AndroidManifest.xml中注册FlutterActivity实现一个简略的跳转。
<activity android:name="io.flutter.embedding.android.FlutterActivity" android:theme="@style/LaunchTheme" android:configChanges="orientation|keyboardHidden|keyboard|screenSize|locale|layoutDirection|fontScale|screenLayout|density|uiMode" android:hardwareAccelerated="true" android:windowSoftInputMode="adjustResize" android:exported="true" />而后在任何页面增加一个跳转代码，比方。
myButton.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { startActivity( FlutterActivity.createDefaultIntent(this) ); }});不过当我运行我的项目，执行跳转的时候还是报错了，谬误的信息如下。
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.snbc.honey_app/io.flutter.embedding.android.FlutterActivity}: java.lang.IllegalStateException: ensureInitializationComplete must be called after startInitialization at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2946) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3081) at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78) at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108) at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1831) at android.os.Handler.dispatchMessage(Handler.java:106) at android.os.Looper.loop(Looper.java:201) at android.app.ActivityThread.main(ActivityThread.java:6806) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:547) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:873)看报错应该是初始化的问题，然而官网文档没有提到任何初始化步骤相干的代码，查查Flutter 官网的issue，示意要加一行初始化代码：
public class MyApplication extends Application { @Override public void onCreate() { super.onCreate(); FlutterMain.startInitialization(this); }}而后，我再次运行，发现报了如下谬误。
java.lang.NoClassDefFoundError: Failed resolution of: Landroid/arch/lifecycle/DefaultLifecycleObserver; at io.flutter.embedding.engine.FlutterEngine.<init>(FlutterEngine.java:152) at io.flutter.embedding.android.FlutterActivityAndFragmentDelegate.setupFlutterEngine(FlutterActivityAndFragmentDelegate.java:221) at io.flutter.embedding.android.FlutterActivityAndFragmentDelegate.onAttach(FlutterActivityAndFragmentDelegate.java:145) at io.flutter.embedding.android.FlutterActivity.onCreate(FlutterActivity.java:399) at android.app.Activity.performCreate(Activity.java:7224) at android.app.Activity.performCreate(Activity.java:7213) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1272) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2926) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3081) at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78) at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108) at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1831) at android.os.Handler.dispatchMessage(Handler.java:106) at android.os.Looper.loop(Looper.java:201) at android.app.ActivityThread.main(ActivityThread.java:6806) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:547) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:873) Caused by: java.lang.ClassNotFoundException: Didn't find class "android.arch.lifecycle.DefaultLifecycleObserver" on path: DexPathList[[zip file "/data/app/com.example.myapplication-kZH0dnJ-qI1ow1NqGOB2ug==/base.apk"],nativeLibraryDirectories=[/data/app/com.example.myapplication-kZH0dnJ-qI1ow1NqGOB2ug==/lib/arm64, /data/app/com.example.myapplication-kZH0dnJ-qI1ow1NqGOB2ug==/base.apk!/lib/arm64-v8a, /system/lib64, /vendor/lib64]]最初的日志给出的提醒是lifecycle缺失，所以增加lifecycle的依赖即可，如下。
implementation 'android.arch.lifecycle:common-java8:1.1.0'而后再次运行就没啥问题了。
5.2 应用FlutterEngine启动
默认状况下，每个FlutterActivity被创立时都会创立一个FlutterEngine，每个FlutterEngine都有一个初始化操作。这意味着在启动一个规范的FlutterActivity时会有肯定的提早。为了缩小此提早，咱们能够在启动FlutterActivity之前事后创立一个FlutterEngine，而后在跳转FlutterActivity时应用FlutterEngine即可。最常见的做法是在Application中先初始化FlutterEngine，比方。
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) }}而后，咱们在跳转FlutterActivity时应用这个缓冲的FlutterEngine即可，因为FlutterEngine初始化的时候曾经增加了engine_id，所以启动的时候须要应用这个engine_id进行启动。
myButton.setOnClickListener { startActivity( FlutterActivity .withCachedEngine("my_engine_id") .build(this) )}当然，在启动的时候，咱们也能够跳转一个默认的路由，只须要在启动的时候调用setInitialRoute办法即可。
class MyApplication : Application() { lateinit var flutterEngine : FlutterEngine override fun onCreate() { super.onCreate() // Instantiate a FlutterEngine. flutterEngine = FlutterEngine(this) // Configure an initial route. flutterEngine.navigationChannel.setInitialRoute("your/route/here"); // Start executing Dart code to pre-warm the FlutterEngine. flutterEngine.dartExecutor.executeDartEntrypoint( DartExecutor.DartEntrypoint.createDefault() ) // Cache the FlutterEngine to be used by FlutterActivity or FlutterFragment. FlutterEngineCache .getInstance() .put("my_engine_id", flutterEngine) }}六、与Flutter通信
通过下面的操作，咱们曾经可能实现原生Android 跳转Flutter，那如何实现Flutter跳转原生Activity或者Flutter如何销毁本人返回原生页面呢？此时就用到了Flutter和原生Android的通迅机制，即Channel，别离是MethodChannel、EventChannel和BasicMessageChannel。
- MethodChannel：用于传递办法调用，是比拟罕用的PlatformChannel。
- EventChannel: 用于传递事件。
- BasicMessageChannel：用于传递数据。
对于这种简略的跳转操作，间接应用MethodChannel即可实现。首先，咱们在flutter_module中新建一个PluginManager的类，而后增加如下代码。
import 'package:flutter/services.dart';class PluginManager { static const MethodChannel _channel = MethodChannel('plugin_demo'); static Future<String> pushFirstActivity(Map params) async { String resultStr = await _channel.invokeMethod('jumpToMain', params); return resultStr; }}而后，当咱们点击Flutter入口页面的返回按钮时，增加一个返回的办法，次要是调用PluginManager发送音讯，如下。
Future<void> backToNative() async { String result; try { result = await PluginManager.pushFirstActivity({'key': 'value'}); } on PlatformException { result = '失败'; } print('backToNative: '+result); }接下来，从新应用flutter build aar从新编译aar包，并在原生Android的Flutter入口页面的configureFlutterEngine办法中增加如下代码。
class FlutterContainerActivity : FlutterActivity() { private val CHANNEL = "plugin_demo" override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) } override fun configureFlutterEngine(flutterEngine: FlutterEngine) { GeneratedPluginRegistrant.registerWith(flutterEngine) MethodChannel(flutterEngine.dartExecutor, CHANNEL).setMethodCallHandler { call, result -> if (call.method == "jumpToMain") { val params = call.argument<String>("key") Toast.makeText(this,"返回原生页面",Toast.LENGTH_SHORT).show() finish() result.success(params) } else { result.notImplemented() } } }}从新运行原生我的项目时，点击Flutter左上角的返回按钮就能够返回到原生页面，其余的混合跳转也能够应用这种形式进行解决。
对于混合开发中混合路由和FlutterEngine多实例的问题，能够参考FlutterBoost。