插件化啟動Activity的過程

在宿主里面的AndroidManifest.xml里面注冊一個空的activity

從開始執(zhí)行execStartActivity到最終將Activity對象new出來這個過程，系統(tǒng)層會去校驗需要啟動的activity的合法性[就是是否有在某個應(yīng)用的AndroidManifest.xml里面注冊]以及按啟動要求創(chuàng)建activity對象。清晰了這點我們就可以很好的繞過系統(tǒng)的約束，達(dá)到我們的目的：【插件中的組件擁有真正生命周期，完全交由系統(tǒng)管理、非反射代理】。 簡單來說方案就兩步： Step1、在開始startActivity的時候?qū)⑿枰獑拥牟寮M件替換成宿主預(yù)先聲明號的。

public ActivityResult execStartActivity(Context who, IBinder contextThread, IBinder token, Activity target, Intent intent, int requestCode, Bundle options) { //如果啟動的是插件的activity組件，這里面將會被替換成宿主預(yù)先聲明的 PluginIntentResolver.resolveActivity(intent); return hackInstrumentation.execStartActivity(who, contextThread, token, target, intent, requestCode, ptions);}

Step2、在最終創(chuàng)建activity對象的時候改回成插件組件的。

@Overridepublic Activity newActivity(ClassLoader cl, String className, Intent intent) throws InstantiationException, IllegalAccessException, ClassNotFoundException { ClassLoader orignalCl = cl; String orginalClassName = className; String orignalIntent = intent.toString(); if (ProcessUtil.isPluginProcess()) { // 將PluginStubActivity替換成插件中的activity if (PluginManagerHelper.isStub(className)) { String action = intent.getAction(); if (action != null && action.contains(PluginIntentResolver.CLASS_SEPARATOR)) {String[] targetClassName = action.split(PluginIntentResolver.CLASS_SEPARATOR);String pluginClassName = targetClassName[0];final String pid = intent.getStringExtra(PluginIntentResolver.INTENT_EXTRA_PID).trim();PluginDescriptor pluginDescriptor = TextUtils.isEmpty(pid) ? PluginManagerHelper.getPluginDescriptorByClassName(pluginClassName) : PluginManagerHelper.getPluginDescriptorByPluginId(pid);Class<?> clazz = PluginLoader.loadPluginClassByName(pluginDescriptor, pluginClassName);if (clazz != null) { className = pluginClassName; cl = clazz.getClassLoader(); intent.setExtrasClassLoader(cl); if (targetClassName.length > 1) { // 之前為了傳遞classNae，intent的action被修改過 // 這里再把Action還原到原始的Action intent.setAction(targetClassName[1]); } else { intent.setAction(null); } // 添加一個標(biāo)記符 intent.addCategory(RELAUNCH_FLAG + className);} else { throw new ClassNotFoundException('pluginClassName : ' + pluginClassName, new Throwable());} } else if (PluginManagerHelper.isExact(className, PluginDescriptor.ACTIVITY)) {// 這個邏輯是為了支持外部app喚起配置了stub_exact的插件ActivityPluginDescriptor pluginDescriptor = PluginManagerHelper.getPluginDescriptorByClassName(className);if (pluginDescriptor != null) { boolean isRunning = PluginLauncher.instance().isRunning(pluginDescriptor.getPackageName()); if (!isRunning) { return waitForLoading(pluginDescriptor); }}Class<?> clazz = PluginLoader.loadPluginClassByName(pluginDescriptor, className);if (clazz != null) { cl = clazz.getClassLoader();} else { throw new ClassNotFoundException('className : ' + className, new Throwable());} } else {// 進(jìn)入這個分支可能是因為activity重啟了，比如橫豎屏切換，由于上面的分支已經(jīng)把Action還原到原始到Action了// 這里只能通過之前添加的標(biāo)記符來查找classNameboolean found = false;Set<String> category = intent.getCategories();if (category != null) { Iterator<String> itr = category.iterator(); while (itr.hasNext()) { String cate = itr.next(); if (cate.startsWith(RELAUNCH_FLAG)) { className = cate.replace(RELAUNCH_FLAG, ''); PluginDescriptor pluginDescriptor = PluginManagerHelper.getPluginDescriptorByClassName(className); if (pluginDescriptor != null) {boolean isRunning = PluginLauncher.instance().isRunning( pluginDescriptor.getPackageName());if (!isRunning) { return waitForLoading(pluginDescriptor);} } Class<?> clazz = PluginLoader.loadPluginClassByName(pluginDescriptor, className); cl = clazz.getClassLoader(); found = true; break; } }}if (!found) { throw new ClassNotFoundException( 'className : ' + className + ', intent : ' + intent.toString(), new Throwable());} } } else { if (cl instanceof PluginClassLoader) {PluginIntentResolver.resolveActivity(intent); } else {// Do Nothing } } } try { Activity activity = super.newActivity(cl, className, intent); if (activity instanceof PluginContainer) { ((PluginContainer) activity).setPluginId(intent.getStringExtra(PluginContainer.FRAGMENT_PLUGIN_ID)); } return activity; } catch (ClassNotFoundException e) { // 收集狀態(tài)，便于異常分析 throw new ClassNotFoundException(' orignalCl : ' + orignalCl.toString() + ', orginalClassName : '+ orginalClassName + ', orignalIntent : ' + orignalIntent + ', currentCl : ' + cl.toString()+ ', currentClassName : ' + className + ', currentIntent : ' + intent.toString() + ', process : '+ ProcessUtil.isPluginProcess() + ', isStubActivity : '+ PluginManagerHelper.isStub(orginalClassName) + ', isExact : '+ PluginManagerHelper.isExact(orginalClassName, PluginDescriptor.ACTIVITY), e); }}

方案確實很簡單，不過還有一些收尾工作，就是將創(chuàng)建好的[插件]組件進(jìn)行一些必要的init操作，比如：在聲明周期onCreate之前進(jìn)行上下文替換等操作，這些都在插件框架提供的PluginInstrumentionWrapper里面進(jìn)行完成的，看一下代碼片段：

@Overridepublic void callActivityOnCreate(Activity activity, Bundle icicle) { PluginInjector.injectActivityContext(activity); Intent intent = activity.getIntent(); if (intent != null) { intent.setExtrasClassLoader(activity.getClassLoader()); } if (icicle != null) { icicle.setClassLoader(activity.getClassLoader()); } if (ProcessUtil.isPluginProcess()) { installPluginViewFactory(activity); if (activity instanceof WaitForLoadingPluginActivity) { // NOTHING } else { } if (activity.isChild()) { // 修正TabActivity中的Activity的ContextImpl的packageName Context base = activity.getBaseContext(); while (base instanceof ContextWrapper) {base = ((ContextWrapper) base).getBaseContext(); } if (HackContextImpl.instanceOf(base)) {HackContextImpl impl = new HackContextImpl(base);String packageName = PluginLoader.getApplication().getPackageName();// String packageName1 = activity.getPackageName();impl.setBasePackageName(packageName);impl.setOpPackageName(packageName); } } } super.callActivityOnCreate(activity, icicle); monitor.onActivityCreate(activity);}

到這插件activity組件就被順序的啟動起來了，并且是系統(tǒng)在維護(hù)具備完整的生命周期。 組件service、Receiver也是一樣的，只是這兩個組件的攔截點在ActivityThread的Handler成員的回調(diào)Callback里面進(jìn)行的。Application和provider在插件啟動的時候進(jìn)行加載。

資源沖突的解決方案resources.arsc資源描述符詳解

packageId: 包名id 資源類型id：string,drawable,layout,color 偏移：某一種類型的偏移值 解決沖突的方案

由于每個插件的包名是不一致的，可以事先規(guī)定某個插件的packageId的值固定，然后修改aapt對其進(jìn)行編譯固定，就可以保證每個插件分配的值不一樣了。

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