携程DynamicAPK插件化框架源码分析
携程DynamicAPK插件化框架源码分析
Author:莫川
插件核心思想
1.aapt的改造
分别对不同的插件项目分配不同的packageId,然后对各个插件的资源进行编译,生成R文件,然后与宿主项目的R文件进行id的合并。
要求:由于最终会将所有的资源文件id进行合并,因此,所有的资源名称均不能相同。
2.运行ClassLoader加载各Bundle
和MultiDex的思路是一样的,所有的插件都被加载到同一个ClassLoader当中,因此,不同插件中的Class必须保持包名和类名的唯一。否则,加载过的类不会再次被加载。
优缺点:各个Bundle之间完全可以相互调用,但是这也造成了各个Bundle之间ClassLoader的非隔离性。并且随着数组的加长,每次findClass的时间会变长,对性能照成一定长度的影响。
让我们在熟悉一下这张图:
在DynamicAPK框架中,每个Bundle被加载到ClassLoader的调用栈如下:
Bundle的Application:BundleBaseApplication
->BundleBaseApplication(onCreate)
->BundleCore(run)
->BundleImpl(optDexFile)
->BundleArchiveRevision(optDexFile)
->BundlePathLoader(installBundleDexs)
->…
如下图所示:
3.热修复
由于所有的插件都被加载到同一个ClassLoader当中,因为,热修复的方案都是从dexElements数组的顺序入手,修改expandFieldArray方法的实现,将修复的类放到dexElements的前方。核心代码如下(详见BundlePathLoader):
private static void expandFieldArray(Object instance, String fieldName, Object[] extraElements,boolean isHotFix) throws NoSuchFieldException, IllegalArgumentException, IllegalAccessException { synchronized (BundlePathLoader.class) { Field jlrField = findField(instance, fieldName); Object[] original = (Object[]) jlrField.get(instance); Object[] combined = (Object[]) Array.newInstance( original.getClass().getComponentType(), original.length + extraElements.length); if(isHotFix) { System.arraycopy(extraElements, 0, combined, 0, extraElements.length); System.arraycopy(original, 0, combined, extraElements.length, original.length); }else { System.arraycopy(original, 0, combined, 0, original.length); System.arraycopy(extraElements, 0, combined, original.length, extraElements.length); } jlrField.set(instance, combined); } }
调用的关键代码如下(HotPatchItem.class):
public void optDexFile() throws Exception{ List<File> files = new ArrayList<File>(); files.add(this.hotFixFile); BundlePathLoader.installBundleDexs(RuntimeArgs.androidApplication.getClassLoader(), storageDir, files, false); } public void optHotFixDexFile() throws Exception{ List<File> files = new ArrayList<File>(); files.add(this.hotFixFile); BundlePathLoader.installBundleDexs(RuntimeArgs.androidApplication.getClassLoader(), storageDir, files, true); }
4.运行时资源的加载
所有插件的资源都加载到DelegateResources中,关键代码如下:
DelegateResources.class
... public static void newDelegateResources(Application application, Resources resources) throws Exception { List<Bundle> bundles = Framework.getBundles(); if (bundles != null && !bundles.isEmpty()) { Resources delegateResources; List<String> arrayList = new ArrayList(); arrayList.add(application.getApplicationInfo().sourceDir); for (Bundle bundle : bundles) { arrayList.add(((BundleImpl) bundle).getArchive().getArchiveFile().getAbsolutePath()); } AssetManager assetManager = AssetManager.class.newInstance(); for (String str : arrayList) { SysHacks.AssetManager_addAssetPath.invoke(assetManager, str); } //处理小米UI资源 if (resources == null || !resources.getClass().getName().equals("android.content.res.MiuiResources")) { delegateResources = new DelegateResources(assetManager, resources); } else { Constructor declaredConstructor = Class.forName("android.content.res.MiuiResources").getDeclaredConstructor(new Class[]{AssetManager.class, DisplayMetrics.class, Configuration.class}); declaredConstructor.setAccessible(true); delegateResources = (Resources) declaredConstructor.newInstance(new Object[]{assetManager, resources.getDisplayMetrics(), resources.getConfiguration()}); } RuntimeArgs.delegateResources = delegateResources; AndroidHack.injectResources(application, delegateResources); StringBuffer stringBuffer = new StringBuffer(); stringBuffer.append("newDelegateResources ["); for (int i = 0; i < arrayList.size(); i++) { if (i > 0) { stringBuffer.append(","); } stringBuffer.append(arrayList.get(i)); } stringBuffer.append("]"); log.log(stringBuffer.toString(), Logger.LogLevel.DBUG); } } ...
上述代码就是将所有Bundle中的资源,通过调用AssetManager的addAssetPath方法,加载到assetManager对象中,然后再用assetManager对象,创建delegateResources对象,并保存在RuntimeArgs.delegateResources当中,然后调用AndroidHack.injectResources方法,对Application和LoadedApk中的mResources成员变量进行注入,代码如下:
public static void injectResources(Application application, Resources resources) throws Exception { Object activityThread = getActivityThread(); if (activityThread == null) { throw new Exception("Failed to get ActivityThread.sCurrentActivityThread"); } Object loadedApk = getLoadedApk(activityThread, application.getPackageName()); if (loadedApk == null) { throw new Exception("Failed to get ActivityThread.mLoadedApk"); } SysHacks.LoadedApk_mResources.set(loadedApk, resources); SysHacks.ContextImpl_mResources.set(application.getBaseContext(), resources); SysHacks.ContextImpl_mTheme.set(application.getBaseContext(), null); }
其中,上述获取LoadedApk的代码,也是通过反射,获取运行时ActivityThread类的LoadedApk对象.
5.运行时动态替换Resource对象
ContextImplHook,动态替换getResources
为了控制startActivity的时候,能够及时替换Activity的Resource和AssetsManager对象,使用ContextImplHook类对Comtext进行替换,然后动态的返回上一步加载的RuntimeArgs.delegateResources委托资源对象。ContextImplHook的核心代码如下:
@Override public Resources getResources() { log.log("getResources is invoke", Logger.LogLevel.INFO); return RuntimeArgs.delegateResources; } @Override public AssetManager getAssets() { log.log("getAssets is invoke", Logger.LogLevel.INFO); return RuntimeArgs.delegateResources.getAssets(); }
如何在Activity跳转过程中,动态的替换呢
通过反射替换ActivityThread的mInstrumentation对象,替换成InstrumentationHook.class,然后就可以在执行startActivity时,拦截其newActivity和callActivityOnCreate方法,在newActivity方法中,动态的替换newActivity的mResources对象。在callActivityOnCreate方法中将ContextImplHook注入到新创建的Activity中。核心代码如下:
@Override public Activity newActivity(Class<?> cls, Context context, IBinder iBinder, Application application, Intent intent, ActivityInfo activityInfo, CharSequence charSequence, Activity activity, String str, Object obj) throws InstantiationException, IllegalAccessException { Activity newActivity = this.mBase.newActivity(cls, context, iBinder, application, intent, activityInfo, charSequence, activity, str, obj); if (RuntimeArgs.androidApplication.getPackageName().equals(activityInfo.packageName) && SysHacks.ContextThemeWrapper_mResources != null) { SysHacks.ContextThemeWrapper_mResources.set(newActivity, RuntimeArgs.delegateResources); } return newActivity; } @Override public Activity newActivity(ClassLoader classLoader, String str, Intent intent) throws InstantiationException, IllegalAccessException, ClassNotFoundException { Activity newActivity; try { newActivity = this.mBase.newActivity(classLoader, str, intent); if (SysHacks.ContextThemeWrapper_mResources != null) { SysHacks.ContextThemeWrapper_mResources.set(newActivity, RuntimeArgs.delegateResources); } } catch (ClassNotFoundException e) { String property = Framework.getProperty("ctrip.android.bundle.welcome", "ctrip.android.view.home.CtripSplashActivity"); if (StringUtil.isEmpty(property)) { throw e; } else { List runningTasks = ((ActivityManager) this.context.getSystemService(Context.ACTIVITY_SERVICE)).getRunningTasks(1); if (runningTasks != null && runningTasks.size() > 0 && ((ActivityManager.RunningTaskInfo) runningTasks.get(0)).numActivities > 1) { if (intent.getComponent() == null) { intent.setClassName(this.context, str); } } log.log("Could not find activity class: " + str, Logger.LogLevel.WARN); log.log("Redirect to welcome activity: " + property, Logger.LogLevel.WARN); newActivity = this.mBase.newActivity(classLoader, property, intent); } } return newActivity; } @Override public void callActivityOnCreate(Activity activity, Bundle bundle) { if (RuntimeArgs.androidApplication.getPackageName().equals(activity.getPackageName())) { ContextImplHook contextImplHook = new ContextImplHook(activity.getBaseContext()); if (!(SysHacks.ContextThemeWrapper_mBase == null || SysHacks.ContextThemeWrapper_mBase.getField() == null)) { SysHacks.ContextThemeWrapper_mBase.set(activity, contextImplHook); } SysHacks.ContextWrapper_mBase.set(activity, contextImplHook); } this.mBase.callActivityOnCreate(activity, bundle); }
总结如下图,Resource的加载和动态替换:
6.插件Activity在宿主AndroidManifest中的预注册
每个插件的Activity,必须在宿主的AndroidManifest.xml中进行注册。
DynamicAPK源码导读:
源代码的目录结构图
- framework
管理各个Bundle以及各个Bundle的封装、版本控制等。
- hack
通过反射的形式,hack类,方法,成员变量等
- hotpatch
热修复相关的封装
- loader
对MultiDex的修改,各Bundle加载到ClassLoader,热修复。
- log
日志管理
- runtime
运行时,对Resources进行动态替换
- util
工具类
博客相关Demo的Github地址
参考
1.AssetManager源码
2.LoadedApk源码
3.ActivityThread源码
4.DynamicAPK源码
来自: http://blog.csdn.net/nupt123456789/article/details/50531709