PlatformChannel功能簡介
PlatformChannel分為BasicMessageChannel、MethodChannel以及EventChannel三種。其各自的主要用途如下：
BasicMessageChannel: 用于傳遞數(shù)據(jù)。Flutter與原生項目的資源是不共享的，可以通過BasicMessageChannel來獲取Native項目的圖標等資源。
MethodChannel: 傳遞方法調(diào)用。Flutter主動調(diào)用Native的方法，并獲取相應的返回值。比如獲取系統(tǒng)電量，發(fā)起Toast等調(diào)用系統(tǒng)API，可以通過這個來完成。
EventChannel: 傳遞事件。這里是Native將事件通知到Flutter。比如Flutter需要監(jiān)聽網(wǎng)絡情況，這時候MethodChannel就無法勝任這個需求了。EventChannel可以將Flutter的一個監(jiān)聽交給Native，Native去做網(wǎng)絡廣播的監(jiān)聽，當收到廣播后借助EventChannel調(diào)用Flutter注冊的監(jiān)聽，完成對Flutter的事件通知。
其實可以看到，無論傳方法還是傳事件，其本質(zhì)上都是數(shù)據(jù)的傳遞，不過上層包的一些邏輯不同而已。
具體實現(xiàn)
1.BasicMessageChannel （可以實現(xiàn)相互傳遞）
flutter
static const messageChannel = const BasicMessageChannel('samples.flutter.io/message', StandardMessageCodec());
static const messageChannel2 = const BasicMessageChannel('samples.flutter.io/message2', StandardMessageCodec());
Future<String> sendMessage() async {
String reply = await messageChannel.send('發(fā)送給Native端的數(shù)據(jù)');
print('reply: $reply');
return reply;
}
void receiveMessage() {
messageChannel2.setMessageHandler((message) async {
print('message: $message');
return '返回Native端的數(shù)據(jù)';
});
}
@override
void initState() {
// TODO: implement initState
super.initState();
receiveMessage();
sendMessage();
}
ios
// 初始化定義
FlutterBasicMessageChannel* messageChannel = [FlutterBasicMessageChannel messageChannelWithName:@"samples.flutter.io/message" binaryMessenger:controller];
// 接收消息監(jiān)聽
[messageChannel setMessageHandler:^(id message, FlutterReply callback) {
NSLog(message);
callback(@"返回flutter端的數(shù)據(jù)");
}];
// 觸發(fā)事件執(zhí)行
FlutterViewController* controller = (FlutterViewController*)self.window.rootViewController;
FlutterBasicMessageChannel* messageChannel2 = [FlutterBasicMessageChannel messageChannelWithName:@"samples.flutter.io/message2" binaryMessenger:controller];
// 發(fā)送消息
[messageChannel2 sendMessage:(@"發(fā)送給flutter的數(shù)據(jù)") reply:^(id reply) {
NSLog(reply);
}];
2.MethodChannel （ Flutter主動調(diào)用Native的方法）
flutter
static const platform = const MethodChannel('samples.flutter.io/battery');
Future<Null> _getBatteryLevel() async {
String batteryLevel;
try {
//關(guān)鍵 platform.invokeMethod('方法名')
final int result = await platform.invokeMethod('getBatteryLevel');
batteryLevel = 'Battery level at $result % .';
} on PlatformException catch (e) {
batteryLevel = "Failed to get battery level: '${e.message}'.";
}
setState(() {
_batteryLevel = batteryLevel;
});
}
// 執(zhí)行_getBatteryLevel方法
ios
FlutterViewController* controller = (FlutterViewController*)self.window.rootViewController;
FlutterMethodChannel* batteryChannel = [FlutterMethodChannel
methodChannelWithName:@"samples.flutter.io/battery"
binaryMessenger:controller];
[batteryChannel setMethodCallHandler:^(FlutterMethodCall* call, FlutterResult result) {
// TODO
if ([@"getBatteryLevel" isEqualToString:call.method]) {
///Do some thing 做一些事
} else {
result(FlutterMethodNotImplemented);
}
}];
3.FlutterEventChannel （Native將事件通知到Flutter）
flutter
static const EventChannel _eventChannel =
const EventChannel('samples.flutter.io/test');
void _onEvent(Object event) {
print('=======返回的內(nèi)容: $event');
//Map eventMap = json.decode(event);
// String parts = eventMap['parts'];
// print("===parts==="+parts);
}
void _onError(Object error) {
print('返回的錯誤');
}
@override
void initState() {
// TODO: implement initState
super.initState();
// 監(jiān)聽開始
_eventChannel.receiveBroadcastStream('123456').listen(_onEvent, onError: _onError);
}
@override
Widget build(BuildContext context) {
print("=======build");
return new Scaffold(
appBar: new AppBar(
title: new Text('TwoPage'),
),
body:ListView(
children: <Widget>[
ListTile(title: Text('1'),),
ListTile(title: Text('2'),),
ListTile(title: Text('3'),),
ListTile(title: Text('4'),),
ListTile(title: Text('5'),),
ListTile(title: Text('6'),),
],
));
}
@override
void dispose() {
super.dispose();
///取消獲取登錄數(shù)據(jù)
if (_eventSub != null) _eventSub.cancel();
}
ios
//1.創(chuàng)建控制器
FlutterViewController* controller = [[FlutterViewController alloc]init];
//2.創(chuàng)建事件渠道
FlutterEventChannel* eventChannel = [FlutterEventChannel eventChannelWithName:@"samples.flutter.io/test" binaryMessenger:controller];
//3.設置代理
[eventChannel setStreamHandler:self];
FlutterEventSink eventSink;
#pragma mark - FlutterStreamHandler代理
// // 這個onListen是Flutter端開始監(jiān)聽這個channel時的回調(diào)，第二個參數(shù) EventSink是用來傳數(shù)據(jù)的載體。
- (FlutterError* _Nullable)onListenWithArguments:(id _Nullable)arguments
eventSink:(FlutterEventSink)events {
eventSink = events;
// arguments flutter給native的參數(shù)
// 回調(diào)給flutter， 建議使用實例指向，因為該block可以使用多次
if (events) {
events(@"主動發(fā)送通知到flutter");//回調(diào)給flutter
}
///可以在此做一些事
NSLog(@"======%@", arguments);
return nil;
}
/// flutter不再接收
- (FlutterError* _Nullable)onCancelWithArguments:(id _Nullable)arguments {
// arguments flutter給native的參數(shù)
///可以在此做一些事
eventSink = nil;
return nil;
}
代碼執(zhí)行順序
//創(chuàng)建完flutterVc 和eventChannel 以后
1.flutter：initState()
2.native：onListenWithArguments
(調(diào)用此方法時，先打印方法名，再打印接收的參數(shù)arguments，因為執(zhí)行events會有短暫的延遲，所以會先打印后面的)
3.native： ======12345
4.flutter: =======build
5.flutter: _onEvent
6.flutter: =======返回的內(nèi)容:主動發(fā)送通知到flutter
4.原生跳Flutter頁面路由傳參
ios setInitialRoute
FlutterViewController *vc = [[FlutterViewController alloc]init];
///初始化路由名稱
[vc setInitialRoute:@"myApp"];
FlutterEventChannel *evenChannal = [FlutterEventChannel eventChannelWithName:@"com.jiaparts.flutter_event/plugin" binaryMessenger:vc];
[evenChannal setStreamHandler:self];
[self.navigationController pushViewController:vc animated:YES];
flutter main.dart
window.defaultRouteName獲取路由名稱
void main() => runApp(_widgetForRoute(window.defaultRouteName));
Widget _widgetForRoute(String route){
return MaterialApp(
home: Scaffold(
resizeToAvoidBottomPadding: false, //輸入框抵住鍵盤 內(nèi)容不隨鍵盤滾動
body: _ylmPage(route)
));
}
Widget _ylmPage(String routeStr){
switch(routeStr){//接收從原生跳轉(zhuǎn)過來的路由，決定跳轉(zhuǎn)哪個頁面
case 'myApp':
return new TwoPage();
default:
return MyApp();
}
}
