Deferred Components-实现Flutter运行时动态下发Dart代码

dependencies {  implementation "com.google.android.play:core:1.8.0"}

@Overrideprotected void onCreate(){ super.onCreate()// 负责deferred components的下载与安装 PlayStoreDeferredComponentManager deferredComponentManager = new  PlayStoreDeferredComponentManager(this, null);FlutterInjector.setInstance(new FlutterInjector.Builder()    .setDeferredComponentManager(deferredComponentManager).build());}
@Overrideprotected void attachBaseContext(Context base) {    super.attachBaseContext(base);    // Emulates installation of future on demand modules using SplitCompat.    SplitCompat.install(this);}

flutter:    deferred-components:

// box.dart
import 'package:flutter/widgets.dart';
/// A simple blue 30x30 box.class DeferredBox extends StatelessWidget {  DeferredBox() {}
  @override  Widget build(BuildContext context) {    return Container(      height: 30,      width: 30,      color: Colors.blue,    );  }}

import 'box.dart' deferred as box;
class SomeWidget extends StatefulWidget {  @override  _SomeWidgetState createState() => _SomeWidgetState();}
class _SomeWidgetState extends State<SomeWidget> {  Future<void> _libraryFuture;
  @override  void initState() { //只有调用了loadLibrary方法，才会去真正下载并安装deferred components.    _libraryFuture = box.loadLibrary();    super.initState();  }
  @override  Widget build(BuildContext context) {    return FutureBuilder<void>(      future: _libraryFuture,      builder: (BuildContext context, AsyncSnapshot<void> snapshot) {        if (snapshot.connectionState == ConnectionState.done) {          if (snapshot.hasError) {            return Text('Error: ${snapshot.error}');          }          return box.DeferredBox();        }        return CircularProgressIndicator();      },    );  }}

 Navigator.push(context, MaterialPageRoute(      builder: (context) {        return const SomeWidget();      },    ));

java -jar bundletool.jar build-apks --bundle=<your_app_project_dir>/build/app/outputs/bundle/release/app-release.aab --output=<your_temp_dir>/app.apks --local-testing
java -jar bundletool.jar install-apks --apks=<your_temp_dir>/app.apks

@Overridepublic void installDeferredComponent(int loadingUnitId, String componentName) {    String resolvedComponentName = componentName != null ? componentName : loadingUnitIdToComponentNames.get(loadingUnitId);    if (resolvedComponentName == null) {         Log.e(TAG, "Deferred component name was null and could not be resolved from loading unit id.");         return;     }     // Handle a loading unit that is included in the base module that does not need download.     if (resolvedComponentName.equals("") && loadingUnitId > 0) {     // No need to load assets as base assets are already loaded.         loadDartLibrary(loadingUnitId, resolvedComponentName);         return;     }     //耗时操作，模拟网络请求去下载android module     new Thread(         () -> {//将so文件从外部存储移动到内部私有存储中              boolean result = moveSoToPrivateDir();              if (result) {                 //模拟网络下载，添加2秒网络延迟                 new Handler(Looper.getMainLooper()).postDelayed(                                () -> {                                    loadAssets(loadingUnitId, resolvedComponentName);                                    loadDartLibrary(loadingUnitId, resolvedComponentName);                                    if (channel != null) {                                        channel.completeInstallSuccess(resolvedComponentName);                                    }                                }                                , 2000);                 } else {                        new Handler(Looper.getMainLooper()).post(                                () -> {                                    Toast.makeText(context, "未在sd卡中找到so文件", Toast.LENGTH_LONG).show();
                                    if (channel != null) {                                        channel.completeInstallError(resolvedComponentName, "未在sd卡中找到so文件");                                    }
                                    if (flutterJNI != null) {                                        flutterJNI.deferredComponentInstallFailure(loadingUnitId, "未在sd卡中找到so文件", true);                                    }                                }                        );                  }              }        ).start();    }

  @Override    public void loadDartLibrary(int loadingUnitId, String componentName) {        if (!verifyJNI()) {            return;        }        // Loading unit must be specified and valid to load a dart library.        //asset-only的component的unit id为-1，不需要加载so文件        if (loadingUnitId < 0) {            return;        }
        //拿到so的文件名字        String aotSharedLibraryName = loadingUnitIdToSharedLibraryNames.get(loadingUnitId);        if (aotSharedLibraryName == null) {            // If the filename is not specified, we use dart's loading unit naming convention.            aotSharedLibraryName = flutterApplicationInfo.aotSharedLibraryName + "-" + loadingUnitId + ".part.so";        }
        //拿到支持的abi格式--arm64_v8a        // Possible values: armeabi, armeabi-v7a, arm64-v8a, x86, x86_64, mips, mips64        String abi;        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {            abi = Build.SUPPORTED_ABIS[0];        } else {            abi = Build.CPU_ABI;        }        String pathAbi = abi.replace("-", "_"); // abis are represented with underscores in paths.
        // TODO(garyq): Optimize this apk/file discovery process to use less i/o and be more        // performant and robust.
        // Search directly in APKs first        List<String> apkPaths = new ArrayList<>();        // If not found in APKs, we check in extracted native libs for the lib directly.        List<String> soPaths = new ArrayList<>();
        Queue<File> searchFiles = new LinkedList<>();        // Downloaded modules are stored here--下载的 modules 存储位置        searchFiles.add(context.getFilesDir());        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {            //第一次通过appbundle形式安装的split apks位置            // The initial installed apks are provided by `sourceDirs` in ApplicationInfo.            // The jniLibs we want are in the splits not the baseDir. These            // APKs are only searched as a fallback, as base libs generally do not need            // to be fully path referenced.            for (String path : context.getApplicationInfo().splitSourceDirs) {                searchFiles.add(new File(path));            }        }
        //查找apk和so文件        while (!searchFiles.isEmpty()) {            File file = searchFiles.remove();            if (file != null && file.isDirectory() && file.listFiles() != null) {                for (File f : file.listFiles()) {                    searchFiles.add(f);                }                continue;            }            String name = file.getName();            // Special case for "split_config" since android base module non-master apks are            // initially installed with the "split_config" prefix/name.            if (name.endsWith(".apk")                    && (name.startsWith(componentName) || name.startsWith("split_config"))                    && name.contains(pathAbi)) {                apkPaths.add(file.getAbsolutePath());                continue;            }            if (name.equals(aotSharedLibraryName)) {                soPaths.add(file.getAbsolutePath());            }        }
        List<String> searchPaths = new ArrayList<>();
        // Add the bare filename as the first search path. In some devices, the so        // file can be dlopen-ed with just the file name.        searchPaths.add(aotSharedLibraryName);
        for (String path : apkPaths) {            searchPaths.add(path + "!lib/" + abi + "/" + aotSharedLibraryName);        }        for (String path : soPaths) {            searchPaths.add(path);        }//打开so文件        flutterJNI.loadDartDeferredLibrary(loadingUnitId, searchPaths.toArray(new String[searchPaths.size()]));    }

override fun onCreate() {        super.onCreate()        val deferredComponentManager = CustomDeferredComponentsManager(this, null)        val injector = FlutterInjector.Builder().setDeferredComponentManager(deferredComponentManager).build()        FlutterInjector.setInstance(injector)