There are three ways to communicate between Flutter and Native terminal:
MethodChannel: The Flutter and the Native can call each other, and the result can be returned after the call. The Native can call the Flutter actively, and the Flutter can call the result actively, which is two-way communication. This is the most common method, and Native calls need to be executed in the main thread.
BasicMessageChannel: Used to encode and decode messages using a specified codec. It is bidirectional communication and can be actively invoked by either the Native end or the Flutter.
EventChannel: Used for the communication of Event Streams. The Native end actively sends data to Flutter, which is usually used to monitor the state of Flutter, such as network changes and sensor data.
The Flutter communicates asynchronously with the Native end.
When the Native endpoint of the Flutter actively sends data to the main thread, the Native endpoint code needs to be executed in the main thread. The Android endpoint jumps from the child thread to the main thread. Handler(looper.getMainLooper ()).post {} Java code:
new Handler(Looper.getMainLooper()).post(new Runnable() {
@Override
public void run() {
}
});
Copy the codeIf the current Activity is available, you can also use the following method: activity.runonuithread {}
Dispatch_async (dispatch_get_main_queue(), ^{}); Swift code: dispatchqueue.main.async {}
The Flutter end creates a MethodChannel to communicate with the native end:
var channel = MethodChannel('com.flutter.guide.MethodChannel'); Com. Flutter. Guide. MethodChannel is MethodChannel, the name of the primary side and the matching.Copy the codeSend a message:
var result = await channel.invokeMethod('sendData',{'name': 'laomeng', 'age': 18})
Copy the codeThe first parameter represents method, the name of the method, which is parsed by the native end. The second parameter represents a parameter of any type. Map is usually used for multiple parameters. Return the Future, the data returned by the native end. Complete code:
class MethodChannelDemo extends StatefulWidget { @override _MethodChannelDemoState createState() => _MethodChannelDemoState(); } class _MethodChannelDemoState extends State<MethodChannelDemo> { var channel = MethodChannel('com.flutter.guide.MethodChannel'); var _data; @override Widget build(BuildContext context) { return Scaffold( appBar: AppBar(), body: Column( children: [SizedBox(height: 50,), RaisedButton(Child: Text(' send data to native '), onPressed: () async { var result = await channel .invokeMethod('sendData', {'name': 'laomeng', 'age': 18}); var name = the result (' name '), var age = result [' age ']; setState (() {_data while forming = '$name, $age;});},), Text (" native return data: $_data') ], ), ); }}Copy the codeCreate MethodChannelDemo on Android:
package com.flutter.guide
import io.flutter.plugin.common.BinaryMessenger
import io.flutter.plugin.common.MethodCall
import io.flutter.plugin.common.MethodChannel
/**
* des:
*/
class MethodChannelDemo(messenger: BinaryMessenger): MethodChannel.MethodCallHandler {
private var channel: MethodChannel
init {
channel = MethodChannel(messenger, "com.flutter.guide.MethodChannel")
channel.setMethodCallHandler(this)
}
override fun onMethodCall(call: MethodCall, result: MethodChannel.Result) {
}
}
Copy the codeThe onMethodCall method calls the invokeMethod callback on the Flutter side as follows:
override fun onMethodCall(call: MethodCall, result: MethodChannel.Result) {
if (call.method == "sendData") {
val name = call.argument("name") as String?
val age = call.argument("age") as Int?
var map = mapOf("name" to "hello,$name",
"age" to "$age"
)
result.success(map)
}
}
Copy the codeThe call.method string is the method passed in by the invokeMethod method. Call. argument is the argument passed to the invokeMethod. Since the Flutter end is passed to a Map, the above resolution is resolved according to the Map. Result.success () is the result returned to Flutter. Var result = await channel. invokeMethod(‘sendData’, {‘name’: ‘laomeng’, ‘age’: 18}); var name = result[‘name’]; var age = result[‘age’]; The parsing at both ends should correspond to each other. Start in MainActivity:
class MainActivity : FlutterActivity() {
override fun configureFlutterEngine(flutterEngine: FlutterEngine) {
super.configureFlutterEngine(flutterEngine)
MethodChannelDemo(flutterEngine.dartExecutor.binaryMessenger)
}
}
Copy the codeIOS To create MethodChannelDemo on iOS, do as follows:
import Flutter
import UIKit
public class MethodChannelDemo {
init(messenger: FlutterBinaryMessenger) {
let channel = FlutterMethodChannel(name: "com.flutter.guide.MethodChannel", binaryMessenger: messenger)
channel.setMethodCallHandler { (call:FlutterMethodCall, result:@escaping FlutterResult) in
if (call.method == "sendData") {
if let dict = call.arguments as? Dictionary<String, Any> {
let name:String = dict["name"] as? String ?? ""
let age:Int = dict["age"] as? Int ?? -1
result(["name":"hello,\(name)","age":age])
}
}
}
}
}
Copy the codeStart in AppDelegate:
import UIKit import Flutter @UIApplicationMain @objc class AppDelegate: FlutterAppDelegate { override func application( _ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]? ) -> Bool { let controller : FlutterViewController = window? .rootViewController as! FlutterViewController MethodChannelDemo(messenger: controller.binaryMessenger) GeneratedPluginRegistrant.register(with: self) return super.application(application, didFinishLaunchingWithOptions: launchOptions) } }Copy the codeThe native end actively sends messages to the Flutter end to receive data
@override
void initState() {
super.initState();
channel.setMethodCallHandler((call) {
setState(() {
_nativeData = call.arguments['count'];
});
});
}
Copy the codeThe Android native starts a timer to send data to the Flutter every second.
class MethodChannelDemo(var activity: Activity, messenger: BinaryMessenger) : MethodChannel.MethodCallHandler {
private var channel: MethodChannel
private var count = 0
init {
channel = MethodChannel(messenger, "com.flutter.guide.MethodChannel")
channel.setMethodCallHandler(this)
startTimer()
}
fun startTimer() {
var timer = Timer().schedule(timerTask {
activity.runOnUiThread {
var map = mapOf("count" to count++)
channel.invokeMethod("timer", map)
}
}, 0, 1000)
}
override fun onMethodCall(call: MethodCall, result: MethodChannel.Result) {
if (call.method == "sendData") {
val name = call.argument("name") as String?
val age = call.argument("age") as Int?
var map = mapOf("name" to "hello,$name",
"age" to "$age"
)
result.success(map)
}
}
}
Copy the codeNote: The data sent by Android should be called in the main scene, i.e. :
Activity.runonuithread {var map = mapOf("count" to count++) channel.invokemethod ("timer", map)} class MainActivity : FlutterActivity() { override fun configureFlutterEngine(flutterEngine: FlutterEngine) { super.configureFlutterEngine(flutterEngine) MethodChannelDemo(this,flutterEngine.dartExecutor.binaryMessenger) flutterEngine.plugins.add(MyPlugin()) } }Copy the codeIOS Sends data. The code for the iOS timer is as follows:
import Flutter
import UIKit
public class MethodChannelDemo {
var count = 0
var channel:FlutterMethodChannel
init(messenger: FlutterBinaryMessenger) {
channel = FlutterMethodChannel(name: "com.flutter.guide.MethodChannel", binaryMessenger: messenger)
channel.setMethodCallHandler { (call:FlutterMethodCall, result:@escaping FlutterResult) in
if (call.method == "sendData") {
if let dict = call.arguments as? Dictionary<String, Any> {
let name:String = dict["name"] as? String ?? ""
let age:Int = dict["age"] as? Int ?? -1
result(["name":"hello,\(name)","age":age])
}
}
}
startTimer()
}
func startTimer() {
var timer = Timer.scheduledTimer(timeInterval:1, target: self, selector:#selector(self.tickDown),userInfo:nil,repeats: true)
}
@objc func tickDown(){
count += 1
var args = ["count":count]
channel.invokeMethod("timer", arguments:args)
}
}
Copy the code