android so 动态化 方案 完整源代码 包括下载器

动态化方案是指在应用程序运行时动态地加载和更新资源和代码，从而实现应用程序的灵活性和可扩展性。在 Android 平台上，常用的动态化方案有插件化、热修复和增量更新等。

以下是一个简单的插件化方案的完整源代码，包括下载器：

1. 创建插件化框架的主要类 PluginManager：

public class PluginManager {
    private Context mContext;
    private static PluginManager sInstance;
    private PluginApk mPluginApk;

    private PluginManager(Context context) {
        mContext = context.getApplicationContext();
    }

    public static PluginManager getInstance(Context context) {
        if (sInstance == null) {
            synchronized (PluginManager.class) {
                if (sInstance == null) {
                    sInstance = new PluginManager(context);
                }
            }
        }
        return sInstance;
    }

    public PluginApk getPluginApk() {
        return mPluginApk;
    }

    public void loadPlugin(String pluginPath) {
        PackageInfo packageInfo = mContext.getPackageManager().getPackageArchiveInfo(pluginPath, PackageManager.GET_ACTIVITIES | PackageManager.GET_SERVICES);
        if (packageInfo == null) {
            return;
        }
        DexClassLoader classLoader = createDexClassLoader(pluginPath);
        AssetManager assetManager = createAssetManager(pluginPath);
        Resources resources = createResources(assetManager);
        mPluginApk = new PluginApk(packageInfo, classLoader, resources);
    }

    private Resources createResources(AssetManager assetManager) {
        Resources superRes = mContext.getResources();
        return new Resources(assetManager, superRes.getDisplayMetrics(), superRes.getConfiguration());
    }

    private AssetManager createAssetManager(String apkPath) {
        try {
            AssetManager assetManager = AssetManager.class.newInstance();
            Method addAssetPath = AssetManager.class.getMethod("addAssetPath", String.class);
            addAssetPath.invoke(assetManager, apkPath);
            return assetManager;
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    private DexClassLoader createDexClassLoader(String apkPath) {
        File dexOutputDir = mContext.getDir("dex", Context.MODE_PRIVATE);
        String dexOutputPath = dexOutputDir.getAbsolutePath();
        DexClassLoader classLoader = new DexClassLoader(apkPath, dexOutputPath, null, mContext.getClassLoader());
        return classLoader;
    }
}

2. 创建插件 APK 的类 PluginApk：

public class PluginApk {
    private PackageInfo mPackageInfo;
    private ClassLoader mClassLoader;
    private Resources mResources;

    public PluginApk(PackageInfo packageInfo, ClassLoader classLoader, Resources resources) {
        mPackageInfo = packageInfo;
        mClassLoader = classLoader;
        mResources = resources;
    }

    public PackageInfo getPackageInfo() {
        return mPackageInfo;
    }

    public ClassLoader getClassLoader() {
        return mClassLoader;
    }

    public Resources getResources() {
        return mResources;
    }
}

3. 创建插件 Activity 的基类 PluginActivity：

public class PluginActivity extends AppCompatActivity {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
    }

    @Override
    public void setContentView(int layoutResID) {
        View view = LayoutInflater.from(this).inflate(layoutResID, null);
        setContentView(view);
    }

    @Override
    public void setContentView(View view) {
        if (view == null) {
            return;
        }
        ViewGroup.LayoutParams params = new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT);
        setContentView(view, params);
    }

    @Override
    public void setContentView(View view, ViewGroup.LayoutParams params) {
        if (view == null) {
            return;
        }
        super.setContentView(view, params);
    }

    @Override
    public Resources getResources() {
        return getPluginResources() == null ? super.getResources() : getPluginResources();
    }

    @Override
    public AssetManager getAssets() {
        return getPluginResources() == null ? super.getAssets() : getPluginResources().getAssets();
    }

    @Override
    public Theme getTheme() {
        return getPluginResources() == null ? super.getTheme() : getPluginResources().newTheme();
    }

    private Resources getPluginResources() {
        PluginApk pluginApk = PluginManager.getInstance(this).getPluginApk();
        return pluginApk != null ? pluginApk.getResources() : null;
    }

    private ClassLoader getPluginClassLoader() {
        PluginApk pluginApk = PluginManager.getInstance(this).getPluginApk();
        return pluginApk != null ? pluginApk.getClassLoader() : null;
    }

    public void startActivity(String className) {
        Intent intent = new Intent();
        intent.setClassName(this, className);
        startActivity(intent);
    }

    public void startActivityFromPlugin(String className) {
        Intent intent = new Intent();
        intent.setClassName(this, className);
        intent.putExtra("FROM_PLUGIN", true);
        startActivity(intent);
    }

    @Override
    protected void attachBaseContext(Context newBase) {
        super.attachBaseContext(newBase);
        // 替换 ContextImpl 中的 mClassLoader
        try {
            Class<?> contextImplClass = Class.forName("android.app.ContextImpl");
            Field mClassLoaderField = contextImplClass.getDeclaredField("mClassLoader");
            mClassLoaderField.setAccessible(true);
            mClassLoaderField.set(newBase, getPluginClassLoader());
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

4. 创建一个插件 Activity 的示例：

public class PluginSampleActivity extends PluginActivity {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_plugin_sample);
        TextView textView = findViewById(R.id.text_view);
        textView.setText(getString(R.string.plugin_string));
    }

    public void onClick(View view) {
        startActivityFromPlugin("com.example.plugin.PluginSampleActivity");
    }
}

5. 创建下载器的类 DownloadUtil：

public class DownloadUtil {
    public static void download(String url, String savePath) {
        OkHttpClient okHttpClient = new OkHttpClient();
        Request request = new Request.Builder().url(url).build();
        try {
            Response response = okHttpClient.newCall(request).execute();
            InputStream inputStream = response.body().byteStream();
            FileOutputStream fileOutputStream = new FileOutputStream(savePath);
            byte[] buffer = new byte[1024];
            int len;
            while ((len = inputStream.read(buffer)) != -1) {
                fileOutputStream.write(buffer, 0, len);
            }
            fileOutputStream.flush();
            inputStream.close();
            fileOutputStream.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

以上是一个简单的插件化方案的完整源代码，包括下载器。