工具插件：pigeon

推薦必看的官方例子：pigeon_plugin_example

其他pigeon寫法的例子：
① pigeon/example
② pigeons

Pigeon is a code generator tool to make communication between Flutter and the host platform type-safe, easier and faster.
一個代碼生成工具鸠信，讓Flutter和宿主平臺更安全纵寝、更簡單、更快地通信星立。

通過Dart入口爽茴，生成兩端通用的模板代碼，原生則只需重寫模板內(nèi)的接口绰垂，無需管理Method Channel的實現(xiàn)室奏。參數(shù)可以通過模板來同步生成。

目前的pigeon只支持生成OC和Java代碼劲装。

1胧沫、命令創(chuàng)建Plugin

$ flutter create --template=plugin --platforms=android,ios -i swift -a kotlin flutter_pigeon_plugin

2、flutter項目中pubspec.yaml的dev_dependencies中占业，添加pigeon插件依賴

dev_dependencies:
  flutter_test:
    sdk: flutter
  flutter_lints: ^1.0.0

  pigeon: 

3绒怨、在Flutter項目的lib目錄外創(chuàng)建一個pigeons文件夾，在pigeons文件夾中創(chuàng)建all_types_pigeon.dart

import 'package:pigeon/pigeon.dart';

class Everything {
  bool? aBool;
  int? anInt;
  double? aDouble;
  String? aString;
  Uint8List? aByteArray;
  Int32List? a4ByteArray;
  Int64List? a8ByteArray;
  Float64List? aFloatArray;
  // ignore: always_specify_types
  List? aList;
  // ignore: always_specify_types
  Map? aMap;
  List<List<bool?>?>? nestedList;
  Map<String?, String?>? mapWithAnnotations;
}

/// Flutter調(diào)用原生的方法
@HostApi()
abstract class HostEverything {
  Everything giveMeEverything();
  Everything echo(Everything everything);
}

/// 原生調(diào)用Flutter的方法
@FlutterApi()
abstract class FlutterEverything {
  Everything giveMeEverythingFlutter();
  Everything echoFlutter(Everything everything);
}

4纺酸、執(zhí)行命令

首先創(chuàng)建存放生成文件的文件夾：
在android/src/mian下創(chuàng)建java/com/example/flutter_pigeon_plugin/文件夾窖逗，存放生成的Java文件。

在項目目錄~/flutter_pigeon_plugin下餐蔬，執(zhí)行以下命令：
$ flutter pub run pigeon --input pigeons/all_types_pigeon.dart --dart_out lib/all_types_pigeon.dart --objc_header_out ios/Classes/AllTypesPigeon.h --objc_source_out ios/Classes/AllTypesPigeon.m --java_out android/src/main/java/com/example/flutter_pigeon_plugin/AllTypesPigeon.java --java_package "com.example.flutter_pigeon_plugin"

命令拆解：
①` flutter pub run pigeon`  
生成代碼的命令

②` --input pigeons/all_types_pigeon.dart `
指定生成代碼的輸入`dart`文件

③ `--dart_out lib/all_types_pigeon.dart `
指定輸出生成`dart`文件的目錄文件

④ `--objc_header_out ios/Classes/AllTypesPigeon.h  `
指定要生成的`iOS`的`.h`文件路徑

⑤ `--objc_source_out ios/Classes/AllTypesPigeon.m  `
指定要生成的`iOS`的`.m`文件路徑

⑥ `--java_out android/src/main/java/com/example/flutter_pigeon_plugin/AllTypesPigeon.java `
指定要生成的`Android`的`.java`文件路徑

⑦  `--java_package "com.example.flutter_pigeon_plugin`
指定`Android`的包名碎紊，在`android/src/main/`下的`AndroidManifest.xml`里的`package`

⑧ `--objc_prefix FLT`（可選）指定生成OC文件的前綴為FLT，前綴自己定義為自己的樊诺。

可以參考官方的例子里的做法：
① 項目目錄下創(chuàng)建一個run_pigeon.sh文件
② 每次有改動仗考，執(zhí)行命令：. ./run_pigeon.sh即可
③ run_pigeon.sh文件內(nèi)容如下：

flutter pub run pigeon \
  --input pigeons/all_types_pigeon.dart \
  --dart_out lib/all_types_pigeon.dart \
  --objc_header_out ios/Classes/AllTypesPigeon.h \
  --objc_source_out ios/Classes/AllTypesPigeon.m \
  --objc_prefix FLT \
  --java_out android/src/main/java/com/example/flutter_pigeon_plugin/AllTypesPigeon.java \
  --java_package "com.example.flutter_pigeon_plugin"

命令執(zhí)行完成，會自動在命令中指定的幾個位置生成響應(yīng)的文件词爬。

5秃嗜、iOS實現(xiàn)Flutter調(diào)用原生的方法

① 刪掉項目中之前的獲取版本的原生的和Flutter側(cè)的相關(guān)channel代碼
② 在AllTypesPigeon.m中自動生成了一個方法HostEverythingSetup

void HostEverythingSetup(id<FlutterBinaryMessenger> binaryMessenger, NSObject<HostEverything> *api) {
  {
    FlutterBasicMessageChannel *channel =
      [FlutterBasicMessageChannel
        messageChannelWithName:@"dev.flutter.pigeon.HostEverything.giveMeEverything"
        binaryMessenger:binaryMessenger
        codec:HostEverythingGetCodec()];
    if (api) {
      NSCAssert([api respondsToSelector:@selector(giveMeEverythingWithError:)], @"HostEverything api doesn't respond to @selector(giveMeEverythingWithError:)");
      [channel setMessageHandler:^(id _Nullable message, FlutterReply callback) {
        FlutterError *error;
        Everything *output = [api giveMeEverythingWithError:&error];
        callback(wrapResult(output, error));
      }];
    }
    else {
      [channel setMessageHandler:nil];
    }
  }
  {
    FlutterBasicMessageChannel *channel =
      [FlutterBasicMessageChannel
        messageChannelWithName:@"dev.flutter.pigeon.HostEverything.echo"
        binaryMessenger:binaryMessenger
        codec:HostEverythingGetCodec()];
    if (api) {
      NSCAssert([api respondsToSelector:@selector(echoEverything:error:)], @"HostEverything api doesn't respond to @selector(echoEverything:error:)");
      [channel setMessageHandler:^(id _Nullable message, FlutterReply callback) {
        NSArray *args = message;
        Everything *arg_everything = args[0];
        FlutterError *error;
        Everything *output = [api echoEverything:arg_everything error:&error];
        callback(wrapResult(output, error));
      }];
    }
    else {
      [channel setMessageHandler:nil];
    }
  }
}

③ 在SwiftFlutterPigeonPlugin.swift的注冊方法里，調(diào)用這個setup方法進行初始化和設(shè)置

    public static func register(with registrar: FlutterPluginRegistrar) {
        let messenger: FlutterBinaryMessenger = registrar.messenger()
        let api: HostEverything & NSObjectProtocol = SwiftFlutterPigeonPlugin.init()
        HostEverythingSetup(messenger, api)
    }

④ SwiftFlutterPigeonPlugin遵循HostEverything協(xié)議顿膨，實現(xiàn)Flutter調(diào)原生的方法

import Flutter
import UIKit

/// 遵循HostEverything協(xié)議锅锨，實現(xiàn)Flutter調(diào)原生的方法
public class SwiftFlutterPigeonPlugin: NSObject, FlutterPlugin, HostEverything {
    public static func register(with registrar: FlutterPluginRegistrar) {
        let messenger: FlutterBinaryMessenger = registrar.messenger()
        let api: HostEverything & NSObjectProtocol = SwiftFlutterPigeonPlugin.init()
        HostEverythingSetup(messenger, api)
    }

    // MARK: HostEverything

    public func giveMeEverythingWithError(_ error: AutoreleasingUnsafeMutablePointer<FlutterError?>) -> Everything? {
        let everyThing = Everything()
        everyThing.aString = "原生返給Flutter的字符串"
        everyThing.aBool = false
        everyThing.anInt = 11
        return everyThing
    }

    /// 遵循HostEverything協(xié)議，實現(xiàn)Flutter調(diào)原生的方法
    public func echo(_ everything: Everything, error: AutoreleasingUnsafeMutablePointer<FlutterError?>) -> Everything? {
        everything.aString = "原生交換的給Flutter的字符串"
        everything.aBool = false
        everything.anInt = 12
        return everything
    }
}

⑤ iOS/Classes目錄下恋沃，創(chuàng)建flutter_pigeon_plugin.h文件必搞，導(dǎo)入頭文件，此文件在iOS自動生成的<flutter_pigeon_plugin/flutter_pigeon_plugin-Swift.h>文件中會自動引用囊咏。

//
//  flutter_pigeon_plugin.h
//  Pods
//
//  Created by yuanzhiying on 2021/9/13.
//

#ifndef flutter_pigeon_plugin_h
#define flutter_pigeon_plugin_h

#import "AllTypesPigeon.h"

#endif /* flutter_pigeon_plugin_h */

6恕洲、 flutter_pigeon_plugin.dart中實現(xiàn)插件調(diào)原生方法

import 'dart:async';

import 'package:flutter_pigeon_plugin/all_types_pigeon.dart';

class FlutterPigeonPlugin {
  static final HostEverything _hostEverything = HostEverything();

  /// Flutter 調(diào)用原生方法
  static Future<Everything> getEverything() async {
    return await _hostEverything.giveMeEverything();
  }

  /// Flutter 調(diào)用原生方法
  static Future<Everything> echoEveryThing(Everything everything) async {
    return await _hostEverything.echo(everything);
  }
}

7塔橡、使用插件的方法

  Future<void> getHostData() async {
    /// 通過插件調(diào)用原生方法
    Everything everything = await FlutterPigeonPlugin.getEverything();
    debugPrint('everything.aString: ${everything.aString}');
    debugPrint('everything.aBool: ${everything.aBool}');
    debugPrint('everything.anInt：${everything.anInt}');
  }

  void echoHostData() async {
    Everything echoEveryThing = Everything();
    echoEveryThing.aString = '我要跟原生交換的字符串';
    echoEveryThing.aBool = true;
    echoEveryThing.anInt = 10;

    /// 通過插件調(diào)用原生方法
    Everything everything = await FlutterPigeonPlugin.echoEveryThing(echoEveryThing);
    debugPrint('everything.aString: ${everything.aString}');
    debugPrint('everything.aBool: ${everything.aBool}');
    debugPrint('everything.anInt：${everything.anInt}');
  }

至此，flutter調(diào)用原生iOS方法完成霜第。

8葛家、flutter調(diào)用安卓原生的實現(xiàn)

① 刪除原有的獲取版本號的channel的代碼
② FlutterPigeonPlugin.kt中繼承AllTypesPigeon.HostEverything，并實現(xiàn)對應(yīng)的方法

  override fun giveMeEverything(): AllTypesPigeon.Everything {
    var everything: AllTypesPigeon.Everything = AllTypesPigeon.Everything()
    everything.aString = "原生返給Flutter的字符串"
    everything.aBool = false
    everything.anInt = 11
    return everything
  }

  override fun echo(everything: AllTypesPigeon.Everything?): AllTypesPigeon.Everything? {
    everything?.aString = "原生交換的給Flutter的字符串"
    everything?.aBool = false
    everything?.anInt = 12
    return everything
  }

③ 通過自動生成的setup方法泌类，進行初始化和設(shè)置

  override fun onAttachedToEngine(@NonNull flutterPluginBinding: FlutterPlugin.FlutterPluginBinding) {
    AllTypesPigeon.HostEverything.setup(flutterPluginBinding.binaryMessenger, this)
  }

  override fun onDetachedFromEngine(@NonNull binding: FlutterPlugin.FlutterPluginBinding) {
    AllTypesPigeon.HostEverything.setup(binding.binaryMessenger, null)
  }

最終如下：

package com.example.flutter_pigeon_plugin

import androidx.annotation.NonNull

import io.flutter.embedding.engine.plugins.FlutterPlugin
import io.flutter.plugin.common.MethodCall
import io.flutter.plugin.common.MethodChannel
import io.flutter.plugin.common.MethodChannel.MethodCallHandler
import io.flutter.plugin.common.MethodChannel.Result

/** FlutterPigeonPlugin */
class FlutterPigeonPlugin: FlutterPlugin, MethodCallHandler, AllTypesPigeon.HostEverything {

  override fun onAttachedToEngine(@NonNull flutterPluginBinding: FlutterPlugin.FlutterPluginBinding) {
    AllTypesPigeon.HostEverything.setup(flutterPluginBinding.binaryMessenger, this)
  }

  override fun onMethodCall(@NonNull call: MethodCall, @NonNull result: Result) {
    result.notImplemented()
  }

  override fun onDetachedFromEngine(@NonNull binding: FlutterPlugin.FlutterPluginBinding) {
    AllTypesPigeon.HostEverything.setup(binding.binaryMessenger, null)
  }

  override fun giveMeEverything(): AllTypesPigeon.Everything {
    var everything: AllTypesPigeon.Everything = AllTypesPigeon.Everything()
    everything.aString = "原生返給Flutter的字符串"
    everything.aBool = false
    everything.anInt = 11
    return everything
  }

  override fun echo(everything: AllTypesPigeon.Everything?): AllTypesPigeon.Everything? {
    everything?.aString = "原生交換的給Flutter的字符串"
    everything?.aBool = false
    everything?.anInt = 12
    return everything
  }
}

項目代碼見：flutter_pigeon_plugin