android深入四大组件（四）广播的注册、发送和接收过程

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1、Android深入四大组件（四）广播的注册、发送和接收过程1.广播的注册过程BroadcastReceiver的注册分为两种，分别是静态注册和动态注册，静态注册在应用安装时由PackageManagerService来完成注册过程，关于这一过程，我会在后续的介绍PackageManagerService文章中详细介绍。这里只介绍BroadcastReceiver的动态注册。要想动态注册BroadcastReceiver，需要调用registerReceiver方法，它的实现在ContextWrapper中，代码如下所示。frameworks/base/core/J

2、ava/android/content/ContextWrapper.javaOverridepublicIntentregisterReceiver(BroadcastReceiverreceiver,IntentFilterfilter){returnmBase.registerReceiver(receiver,filter);}ContextImpl的registerReceiver方法有很多重载的方法最终会调用registerReceiverInternal方法：frameworks/base/core/java/android/app/ContextI

3、mpl.javaprivateIntentregisterReceiverInternal(BroadcastReceiverreceiver,intuserId,IntentFilterfilter,StringbroadcastPermission,Handlerscheduler,Contextcontext){IIntentReceiverrd=null;if(receiver!=null){if(mPackageInfo!=null&&context!=null){//1if(scheduler==null){scheduler=mMainThread.

4、getHandler();}rd=mPackageInfo.getReceiverDispatcher(receiver,context,scheduler,mMainThread.getInstrumentation(),true);//2}else{if(scheduler==null){scheduler=mMainThread.getHandler();}rd=newLoadedApk.ReceiverDispatcher(receiver,context,scheduler,null,true).getIIntentReceiver();//3}}try

5、{finalIntentintent=ActivityManagerNative.getDefault().registerReceiver(mMainThread.getApplicationThread(),mBasePackageName,rd,filter,broadcastPermission,userId);//4if(intent!=null){intent.setExtrasClassLoader(getClassLoader());intent.prepareToEnterProcess();}returnintent;}catch(Remote

6、Exceptione){throwe.rethrowFromSystemServer();}在注释1处判断如果LoadedApk类型的mPackageInfo不等于null并且context不等null就调用注释2处的代码通过mPackageInfo的getReceiverDispatcher方法获取rd对象，否则就调用注释3处的代码来创建rd对象。注释2和3的代码的目的都是要获取IIntentReceiver类型的rd对象，IIntentReceiver是一个Binder接口，用于进行跨进程的通信，它的具体实现在LoadedApk.ReceiverDispatc

7、her.InnerReceiver，如下所示。frameworks/base/core/java/android/app/LoadedApk.javastaticfinalclassReceiverDispatcher{finalstaticclassInnerReceiverextendsIIntentReceiver.Stub{finalWeakReferencemDispatcher;finalLoadedApk.ReceiverDispatchermStrongRef;InnerReceiver(

8、Loade