Flutter开发进阶之Package

通常我们在Flutter开发中需要将部分功能与整体项目隔离，一般有两种方案Plugin和Package，Application是作为主体项目，Module是作为原生项目接入Flutter模块。
Flutter开发进阶
当独立模块不需要与原生项目通讯只需要Plugin就可以，但是当需要与原生通讯就需要Package。

一、创建Package

cd /Users/kevin/Desktop/Myflutter create --org com.kevin --template=plugin --platforms=android,ios -a kotlin -i swift  package_demo

创建Package必须指定平台：
android、ios、web、linux、macos 和 windows。
命令中-a后是指定Android的开发语言，-i是指定iOS的开发语言。
Package

二、通讯

Package会自动创建MethodChannel，还可以根据需要创建BasicMessageChannel和EventChannel。

Flutter

class MethodChannelPackageDemo extends PackageDemoPlatform {/// The method channel used to interact with the native platform.@visibleForTestingfinal methodChannel = const MethodChannel('package_demo_method');final messageChannel = const BasicMessageChannel('package_demo_message', StandardMessageCodec());final eventChannel = const EventChannel('package_demo_event');MethodChannelPackageDemo() {methodChannel.setMethodCallHandler((call) async {/// 方法return call.method;});messageChannel.setMessageHandler((message) async {/// 字符串和半结构化return message;});eventChannel.receiveBroadcastStream().listen((event) {/// 事件流}, onError: (error) {///}, cancelOnError: true,);}@overrideFuture<String?> getPlatformVersion() async {final version = await methodChannel.invokeMethod<String>('getPlatformVersion');return version;}
}

iOS

public class PackageDemoPlugin: NSObject, FlutterPlugin {public static func register(with registrar: FlutterPluginRegistrar) {let methodChannel = FlutterMethodChannel(name: "package_demo_method", binaryMessenger: registrar.messenger())let instance = PackageDemoPlugin()registrar.addMethodCallDelegate(instance, channel: methodChannel)}public func handle(_ call: FlutterMethodCall, result: @escaping FlutterResult) {switch call.method {case "getPlatformVersion":result("iOS " + UIDevice.current.systemVersion)default:result(FlutterMethodNotImplemented)}}
}

Android

class PackageDemoPlugin: FlutterPlugin, MethodCallHandler {/// The MethodChannel that will the communication between Flutter and native Android////// This local reference serves to register the plugin with the Flutter Engine and unregister it/// when the Flutter Engine is detached from the Activityprivate lateinit var methodChannel : MethodChanneloverride fun onAttachedToEngine(flutterPluginBinding: FlutterPlugin.FlutterPluginBinding) {methodChannel = MethodChannel(flutterPluginBinding.binaryMessenger, "package_demo_method")methodChannel.setMethodCallHandler(this)}override fun onMethodCall(call: MethodCall, result: Result) {if (call.method == "getPlatformVersion") {result.success("Android ${android.os.Build.VERSION.RELEASE}")} else {result.notImplemented()}}override fun onDetachedFromEngine(binding: FlutterPlugin.FlutterPluginBinding) {channel.setMethodCallHandler(null)}
}

三、调用原生控件

Flutter

class PackageView extends StatelessWidget {const PackageView({super.key});@overrideWidget build(BuildContext context) {// TODO: implement buildif (Platform.isAndroid) {return AndroidView(viewType: 'package_demo/android',onPlatformViewCreated: (id) {},creationParams: const {'type': 'android'},creationParamsCodec: const StandardMessageCodec(),);} else if (Platform.isIOS) {return UiKitView(viewType: 'package_demo/ios',onPlatformViewCreated: (id) {},creationParams: const {'type': 'ios'},creationParamsCodec: const StandardMessageCodec(),);}return const SizedBox();}
}

iOS

public class PackageDemoPlugin: NSObject, FlutterPlugin {public static func register(with registrar: FlutterPluginRegistrar) {let methodChannel = FlutterMethodChannel(name: "package_demo_method", binaryMessenger: registrar.messenger())let instance = PackageDemoPlugin()registrar.addMethodCallDelegate(instance, channel: methodChannel)registrar.register(PackageViewFactory(), withId: "package_demo/ios")}public func handle(_ call: FlutterMethodCall, result: @escaping FlutterResult) {switch call.method {case "getPlatformVersion":result("iOS " + UIDevice.current.systemVersion)default:result(FlutterMethodNotImplemented)}}
}class PackageViewFactory: NSObject, FlutterPlatformViewFactory {func create(withFrame frame: CGRect, viewIdentifier viewId: Int64, arguments args: Any?) -> FlutterPlatformView {return PackageView()}func createArgsCodec() -> FlutterMessageCodec & NSObjectProtocol {return FlutterStandardMessageCodec.sharedInstance()}}class PackageView: NSObject, FlutterPlatformView {func view() -> UIView {return UIView()}}

Android

class PackageDemoPlugin: FlutterPlugin, MethodCallHandler {/// The MethodChannel that will the communication between Flutter and native Android////// This local reference serves to register the plugin with the Flutter Engine and unregister it/// when the Flutter Engine is detached from the Activityprivate lateinit var methodChannel : MethodChanneloverride fun onAttachedToEngine(flutterPluginBinding: FlutterPlugin.FlutterPluginBinding) {methodChannel = MethodChannel(flutterPluginBinding.binaryMessenger, "package_demo_method")methodChannel.setMethodCallHandler(this)flutterPluginBinding.platformViewRegistry.registerViewFactory("package_demo/android", PackageViewFactory());}override fun onMethodCall(call: MethodCall, result: Result) {if (call.method == "getPlatformVersion") {result.success("Android ${android.os.Build.VERSION.RELEASE}")} else {result.notImplemented()}}override fun onDetachedFromEngine(binding: FlutterPlugin.FlutterPluginBinding) {methodChannel.setMethodCallHandler(null)}
}class PackageViewFactory: PlatformViewFactory(StandardMessageCodec.INSTANCE){override fun create(context: Context?, viewId: Int, args: Any?): PlatformView {return PackageView(context)}}class PackageView internal constructor(context: Context?): PlatformView{override fun getView(): View? {TODO("Not yet implemented")}override fun dispose() {TODO("Not yet implemented")}}