Flutter學(xué)習(xí)之旅-混合開發(fā)Part1

場景

  1. Flutter項(xiàng)目中需要與Native進(jìn)行通信
  2. Android原生項(xiàng)目嵌入Flutter開發(fā)模塊
  3. iOS原生項(xiàng)目嵌入Flutter開發(fā)模塊
  4. Flutter插件開發(fā)
image

平臺(tái)通道數(shù)據(jù)類型支持

Dart Android iOS
null null nil (NSNull when nested)
bool java.lang.Boolean NSNumber numberWithBool:
int java.lang.Integer NSNumber numberWithInt:
int, 如果不足32位 java.lang.Long NSNumber numberWithLong:
int, 如果不足64位 java.math.BigInteger FlutterStandardBigInteger
double java.lang.Double NSNumber numberWithDouble:
String java.lang.String NSString
Uint8List byte[] FlutterStandardTypedData typedDataWithBytes:
Int32List int[] FlutterStandardTypedData typedDataWithInt32:
Int64List long[] FlutterStandardTypedData typedDataWithInt64:
Float64List double[] FlutterStandardTypedData typedDataWithFloat64:
List java.util.ArrayList NSArray
Map java.util.HashMap NSDictionary

當(dāng)在發(fā)送和接收值時(shí)，這些值在消息中的序列化和反序列化會(huì)自動(dòng)進(jìn)行。

平臺(tái)通道

Platform Channel 是所以 Flutter 提供的和平臺(tái)端通信的工具，針對不同的使用場景，Platform Channel 又分為以下三類：

  1. Message channel：用于傳遞字符串和半結(jié)構(gòu)化的信息,支持使用自定義消息編解碼器進(jìn)行基本的異步消息傳遞
  2. Method channel：用于傳遞方法調(diào)用（method invocation）
  3. Event channel：用于數(shù)據(jù)流（event streams）的通信,通常用在需要進(jìn)行實(shí)時(shí)監(jiān)聽的使用場景，比如：網(wǎng)絡(luò)狀態(tài)，電池充電狀態(tài)以及一些監(jiān)聽器的實(shí)現(xiàn)

Flutter項(xiàng)目中需要與Native進(jìn)行通信-實(shí)戰(zhàn)

我們這里僅使用Method channel和Event channel進(jìn)行通信實(shí)戰(zhàn)

要實(shí)現(xiàn)的功能：

  1. Flutter給Native傳遞三個(gè)參數(shù)，Native要把這三個(gè)參數(shù)相加得到的結(jié)果返回給Flutter，并顯示在Flutter界面上
  2. Native寫一個(gè)定時(shí)器，每隔1秒進(jìn)行“+1操作”，每次“+1”后，把結(jié)果傳遞給Flutter，當(dāng)結(jié)果大于30的時(shí)候結(jié)束定時(shí)器
功能1：
Android端：

創(chuàng)建MethodChannelDemo.kt

class MethodChannelDemo (messenger: BinaryMessenger): MethodChannel.MethodCallHandler{

    private var channel: MethodChannel = MethodChannel(messenger, "com.mufeng.flutterNativeChannel.MethodChannel")

    init {
        channel.setMethodCallHandler(this)
    }

    override fun onMethodCall(call: MethodCall, result: MethodChannel.Result) {
        when(call.method){
            "add" -> {
                val params1 = call.argument<Int>("params1")
                val params2 = call.argument<Int>("params2")
                val params3 = call.argument<Int>("params3")
                val params = params1!! + params2!! + params3!!
                result.success(params)
            }
        }
    }
}

在MainActivity中啟動(dòng)平臺(tái)通道

class MainActivity: FlutterActivity() {
    override fun configureFlutterEngine(flutterEngine: FlutterEngine) {
        super.configureFlutterEngine(flutterEngine)
        MethodChannelDemo(flutterEngine.dartExecutor.binaryMessenger)
    }
}
iOS端

創(chuàng)建MethodChannelDemo.swift

//
//  MethodChannelDemo.swift
//  Runner
//
//  Created by a on 2020/12/28.
//

import Foundation

import Flutter
import UIKit

public class MethodChannelDemo {
    init(messenger: FlutterBinaryMessenger) {
        let channel = FlutterMethodChannel(name: "com.mufeng.flutterNativeChannel.MethodChannel", binaryMessenger: messenger)
        channel.setMethodCallHandler{ (call: FlutterMethodCall, result:@escaping FlutterResult)in
            if(call.method == "add"){
                if let dict = call.arguments as? Dictionary<String, Any>{
                    let params1: Int = dict["params1"] as? Int ?? 0
                    let params2: Int = dict["params2"] as? Int ?? 0
                    let params3: Int = dict["params3"] as? Int ?? 0
                    result(params1 + params2 + params3)
                }
            }
        }
    }
}

在 AppDelegate 中啟動(dòng)平臺(tái)通道：

import UIKit
import Flutter

@UIApplicationMain
@objc class AppDelegate: FlutterAppDelegate {
  override func application(
    _ application: UIApplication,
    didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
  ) -> Bool {
    
    /// start
    let controller: FlutterViewController = window?.rootViewController as! FlutterViewController
    MethodChannelDemo(messenger: controller.binaryMessenger)
    /// end
    GeneratedPluginRegistrant.register(with: self)
    return super.application(application, didFinishLaunchingWithOptions: launchOptions)
  }
}

在ios中也用同樣的操作，要保證平臺(tái)通道的channel保持一致，這樣在Flutter中就可以保證一套代碼試用兩個(gè)平臺(tái)了

Flutter
 /// 保證平臺(tái)channel保持一致
 var channel = MethodChannel('com.mufeng.flutterNativeChannel.MethodChannel');
 var result = await channel.invokeMethod('add', {'params1': int.parse(controller1.text), 'params2': int.parse(controller2.text), 'params3': int.parse(controller3.text)});
 setState(() {
   this.result = result.toString();
 });
顯示結(jié)果：

Android：


image

iOS:


image
功能2：
Android端

android 下創(chuàng)建 EventChannelDemo：

package com.mufeng.flutter_native_channel

import android.app.Activity
import io.flutter.plugin.common.BinaryMessenger
import io.flutter.plugin.common.EventChannel
import java.util.*
import kotlin.concurrent.timerTask

class EventChannelDemo(private var activity: Activity, messenger: BinaryMessenger) : EventChannel.StreamHandler {

    private var channel: EventChannel = EventChannel(messenger, "com.mufeng.flutterNativeChannel.EventChannel")
    private var count = 0
    private var events: EventChannel.EventSink? = null
    init {
        channel.setStreamHandler(this)
        startTimer()
    }

    private fun startTimer() {
        var timer = Timer().schedule(timerTask {
            count++
            val map = mapOf("count" to count)
            activity.runOnUiThread {
                // 必須運(yùn)行在主線程
                events?.success(map)
            }
            if(count >= 30){
                 activity.runOnUiThread {
                    events?.error("400", "超過30秒,倒計(jì)時(shí)結(jié)束", null)
                }
                cancel()
            }
        }, 0, 1000)
    }

    override fun onListen(arguments: Any?, events: EventChannel.EventSink?) {
        this.events = events
    }

    override fun onCancel(arguments: Any?) {
        this.events = null
    }
}

在 MainActivity 啟動(dòng)：

class MainActivity: FlutterActivity() {
    override fun configureFlutterEngine(flutterEngine: FlutterEngine) {
        super.configureFlutterEngine(flutterEngine)
        // MethodChannelDemo(flutterEngine.dartExecutor.binaryMessenger)
        EventChannelDemo(this, flutterEngine.dartExecutor.binaryMessenger)
    }
}
iOS端

ios 下創(chuàng)建 EventChannelDemo


import Foundation
import Flutter
import UIKit

public class EventChannelDemo: NSObject, FlutterStreamHandler {
    var channel: FlutterEventChannel?
    var count = 0
    var events: FlutterEventSink?
    var timer: Timer?
    
    public override init() {
        super.init()
    }
    
    convenience init(messenger: FlutterBinaryMessenger) {
        self.init()
        
        channel = FlutterEventChannel(name: "com.mufeng.flutterNativeChannel.EventChannel", binaryMessenger: messenger)
        channel?.setStreamHandler(self)
        startTimer()
    }
    
    func startTimer() {
        timer = Timer.scheduledTimer(timeInterval: 1, target: self,selector: #selector(self.tickDown),userInfo: nil,repeats: true)
    }
    
    @objc func tickDown(){
        count += 1
        let args = ["count": count]
        if(events != nil){
            events!(args)
        }
        if(count >= 30){
            if(events != nil){
                events!(FlutterError.init(code: "400", message: "超過30秒,倒計(jì)時(shí)結(jié)束", details: nil))
            }
            timer?.fireDate = Date.distantFuture
            timer?.invalidate()
        }
    }
    
    public func onListen(withArguments arguments: Any?, eventSink events: @escaping FlutterEventSink) -> FlutterError? {
        self.events = events
        return nil
    }
    
    public func onCancel(withArguments arguments: Any?) -> FlutterError? {
        self.events = nil
        timer?.invalidate()
        self.timer = nil
        return nil
    }
}

在 AppDelegate 啟動(dòng)：

@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)
    EventChannelDemo(messenger: controller.binaryMessenger)
    GeneratedPluginRegistrant.register(with: self)
    return super.application(application, didFinishLaunchingWithOptions: launchOptions)
  }
}
Flutter端
var _eventChannel = EventChannel('com.mufeng.flutterNativeChannel.EventChannel');

_eventChannel.receiveBroadcastStream().listen(_listen, onError: (value){
      print(value);
    });
    
  void _listen(event) {
    setState(() {
      second = event['count'].toString();
    });
  }
顯示結(jié)果

Android：

// 打印出原生發(fā)揮的錯(cuò)誤信息
I/flutter (24053): PlatformException(400, 超過30秒,倒計(jì)時(shí)結(jié)束, null, null)
image

iOS：

// 打印出原生發(fā)揮的錯(cuò)誤信息
flutter: PlatformException(400, 超過30秒,倒計(jì)時(shí)結(jié)束, null, null)
image

源碼地址：flutter_native_channel

總結(jié)

Flutter 與 Native 通信在 Flutter 應(yīng)用中幾乎是不可缺少的步驟，所以掌握其原理和實(shí)際用法尤其重要。熟練的掌握Flutter與Native的通信能極大的提高開發(fā)效率

感謝

老孟Flutter

Flutter中文網(wǎng)-Flutter實(shí)戰(zhàn)

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