Flutter混合開發(fā)和Android動態(tài)更新實踐

感謝閑魚和csdn的文章給的思路：

閑魚flutter混合工程持續(xù)集成的最佳實踐

深入理解 Flutter 的編譯原理與優(yōu)化

Flutter混合開發(fā)和動態(tài)更新的探索歷程 Android版

本篇是實踐性文章包含兩部分

1. 將Flutter工程編譯后的文件集成到Android項目
2. 將Flutter代碼熱更新

不涉及源碼和理論，想要了解的話可以閱讀上面的文章

將Flutter工程編譯后的文件集成到Android項目

? 因為Flutter無法完全替代原生絕大部分項目都是Flutter和Native混合開發(fā)的模式，所以存在一部分同學只做Native開發(fā)，并不熟悉Flutter技術(shù)。如果直接采用Flutter工程來開發(fā)，那這部分原生開發(fā)同學也需要配置Flutter環(huán)境，學習Flutter。

? 由于上述原因，所以采用flutter項目和原生項目相互獨立開發(fā)，將flutter項目編譯后的文件以module的形式集成到Android項目中。

原理：Android項目依賴flutter的文件

1. Flutter庫

   主要是flutter.jar，文件位于Flutter SDK目錄下flutter/bin/cache/artifacts/engine

2. Flutter工程編譯文件

   isolate_snapshot_data、isolate_snapshot_instr、vm_snapshot_data、vm_snapshot_instr、flutter_assets下所有文件

   位于Flutter工程build/app/intermediates/flutter/release/下

3. Flutter Plugin編譯文件(暫時沒用到，待補充)

集成步驟

1. 在原生項目中新建一個module例如fluttermodule

2. 將flutter.jar放入libs文件夾

3. 將isolate_snapshot_data、isolate_snapshot_instr、vm_snapshot_data、vm_snapshot_instr和flutter_assets下所有文件放入assets/flutter_assets/下

   為了方便可以在flutter項目中用gradle腳本實現(xiàn)，例如

   task copyAndroidFlutterModule << {
       println "project.rootDir = ${project.rootDir}/"
   
       println "buildDir = ${this.buildDir}/"
       def flutterOutputDir = "${this.buildDir}/flutter_android_output/flutter_module/"
       def flutterPluginFile = new File(flutterOutputDir)
       if (!flutterPluginFile.exists()) {
           flutterPluginFile.mkdirs()
       } else {
           flutterPluginFile.deleteDir()
       }
       def flutterReleaseBuildDir = "${this.buildDir}/app/intermediates/flutter/release/"
       println "flutterReleaseBuildDir=$flutterReleaseBuildDir"
       //復制snapshot_data和snapshot_instr
       project.copy {
           from flutterReleaseBuildDir
           include "*snapshot_data"
           include "*snapshot_instr"
           into flutterOutputDir
       }
       //復制flutter_assets
       project.copy {
           from "${flutterReleaseBuildDir}flutter_assets/"
           into flutterOutputDir
       }
   }
   

4. 將application指定為FlutterApplication或者自定義類集成FlutterApplication

   <application
           android:allowBackup="true"
           android:icon="@mipmap/ic_launcher"
           android:label="@string/app_name"
           android:name="io.flutter.app.FlutterApplication"
           android:roundIcon="@mipmap/ic_launcher_round"
           android:supportsRtl="true"
           android:theme="@style/AppTheme">
     </application>
   

5. 新建Activity繼承FlutterActivity

   package com.gmail.jackxuechen.fluttermodel;
   
   import android.os.Bundle;
   import io.flutter.app.FlutterActivity;
   
   public class FlutterRootActivity extends FlutterActivity {
     @Override
     protected void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
       GeneratedPluginRegistrant.registerWith(this);
     }
   }
   

6. 集成成功

Android動態(tài)更新

原理：替換/data/data/包名/app_flutter/flutter_assets/

下的isolate_snapshot_data、isolate_snapshot_instr、vm_snapshot_data、vm_snapshot_instr即可實現(xiàn)flutter項目的更新

為了方便可以寫個gradle腳本將flutter工程編譯的isolate_snapshot_data、isolate_snapshot_instr、vm_snapshot_data、vm_snapshot_instr文件放到一個單獨文件夾

task copyAndroidFlutterAssets << {
    println "project.rootDir = ${project.rootDir}/"
    println "buildDir = ${this.buildDir}/"
    def flutterOutputDir = "${this.buildDir}/flutter_android_output/flutter_assets/"
    def flutterPluginFile = new File(flutterOutputDir)
    if (!flutterPluginFile.exists()) {
        flutterPluginFile.mkdirs()
    } else {
        flutterPluginFile.deleteDir()
    }
    def flutterReleaseBuildDir = "${this.buildDir}/app/intermediates/flutter/release/"
    println "flutterReleaseBuildDir=$flutterReleaseBuildDir"
    //復制snapshot_data和snapshot_instr
    project.copy {
        from flutterReleaseBuildDir
        include "*snapshot_data"
        include "*snapshot_instr"
        into flutterOutputDir
    }
}

注意事項

1. vm_snapshot_data、vm_snapshot_instr和flutter sdk版本有關(guān)，生成更新文件時應保持和集成到原生項目中的flutter sdk版本一致

2. 因為isolate_snapshot_data、isolate_snapshot_instr、vm_snapshot_data、vm_snapshot_instr可能是在FlutterApplication中處理(需要看源碼目前還沒研究到)的。如果直接替換相關(guān)文件而沒有冷啟動，可能會導致崩潰，不過可以通過升級邏輯實現(xiàn)冷啟更新，類型騰訊tinker。

3. 如果flutter項目中添加新的依賴原生的插件，則無法通過替換flutter編譯后的文件升級，強制升級會崩潰