推荐下载Android Broadcast广播机制分析Word文件下载.docx

推荐下载Android Broadcast广播机制分析Word文件下载.docx

《推荐下载Android Broadcast广播机制分析Word文件下载.docx》由会员分享，可在线阅读，更多相关《推荐下载Android Broadcast广播机制分析Word文件下载.docx（47页珍藏版）》请在冰豆网上搜索。

 普通广播：

通过Context.sendBroadcast（）发送，可并行处理有序广播：

通过

Context.sendOrderedBroadcast（）发送，串行处理Sticky广播：

Context.sendOrderedBroadcast（）发送二、注册广播2.1registerReceiver广播注册，对

于应用开发来说，往往是在Activity/Service中调用registerReceiver（）方法，而

Activity/Service都间接继承于Context抽象类，真正干活是交给ContextImpl类。

另

外调用getOuterContext（）可获取最外层的调用者Activity/Service。

 [ContextImpl.java]

 @OverridepublicIntentregisterReceiver（BroadcastReceiverreceiver,IntentFilterfilter）

{returnregisterReceiver（receiver,filter,null,null）;

}@OverridepublicIntent

registerReceiver（BroadcastReceiverreceiver,IntentFilterfilter,String

broadcastPermission,Handlerscheduler）{//【见小节2.2】return

registerReceiverInternal（receiver,getUserId（）,filter,broadcastPermission,scheduler,

getOuterContext（））;

}当执行两参数的registerReceiver方法，增加两个

broadcastPermission=null和scheduler=null调用四参数的注册方法。

其中

broadcastPermission拥有广播的权限控制，scheduler用于指定接收到广播时

onRecive执行线程，当scheduler=null则默认代表在主线程中执行，这也是最常见的

用法。

再然后调用6参数的registerReceiverInternal。

 2.2registerReceiverInternal[ContextImpl.java]

 privateIntentregisterReceiverInternal（BroadcastReceiverreceiver,intuserId,

IntentFilterfilter,StringbroadcastPermission,Handlerscheduler,Contextcontext）{

IIntentReceiverrd=null;

if（receiver!

=null）{if（mPackageInfo!

=nullcontext!

=null）{

if（scheduler==null）{//将主线程Handler赋予scheulerscheduler=

mMainThread.getHandler（）;

}//获取IIntentReceiver对象【2.3】rd=

mPackageInfo.getReceiverDispatcher（receiver,context,scheduler,

mMainThread.getInstrumentation（）,true）;

}else{if（scheduler==null）{scheduler=

}rd=newLoadedApk.ReceiverDispatcher（receiver,context,

scheduler,null,true）.getIIntentReceiver（）;

}}try{//调用AMP.registerReceiver【2.4】

returnActivityManagerNative.getDefault（）.registerReceiver（

mMainThread.getApplicationThread（）,mBasePackageName,rd,filter,

broadcastPermission,userId）;

}catch（RemoteExceptione）{return

null;

}}ActivityManagerNative.getDefault（）返回的是ActivityManagerProxy对象，简称

AMP，该方法中参数有mMainThread.getApplicationThread（）返回的是

ApplicationThread，这是Binder的Bn端，用于system_server进程与该进程的通

信。

 2.3LoadedApk.getReceiverDispatcher[-LoadedApk.java]

 publicIIntentReceivergetReceiverDispatcher（BroadcastReceiverr,Contextcontext,

Handlerhandler,Instrumentationinstrumentation,booleanregistered）{synchronized

（mReceivers）{LoadedApk.ReceiverDispatcherrd=null;

ArrayMapBroadcastReceiver,

LoadedApk.ReceiverDispatchermap=null;

//此处registered=true，则进入该分支if

（registered）{map=mReceivers.get（context）;

if（map!

=null）{rd=map.get（r）;

}}if

（rd==null）{//当广播分发者为空，则创建ReceiverDispatcher【2.3.1】rd=new

ReceiverDispatcher（r,context,handler,instrumentation,registered）;

if（registered）{if

（map==null）{map=newArrayMapBroadcastReceiver,

LoadedApk.ReceiverDispatchermReceivers.put（context,map）;

}map.put（r,rd）;

}}else

{//验证广播分发者的context、handler是否一致rd.validate（context,handler）;

}

rd.mForgotten=false;

//获取IIntentReceiver对象returnrd.getIIntentReceiver（）;

}}不妨

令以BroadcastReceiver（广播接收者）为key，LoadedApk.ReceiverDispatcher（分发者）

为value的ArrayMap记为A。

此处mReceivers是一个以Context为key，以A为

value的ArrayMap。

对于ReceiverDispatcher（广播分发者），当不存在时则创建一

个。

 2.3.1创建ReceiverDispatcher

 ReceiverDispatcher（BroadcastReceiverreceiver,Contextcontext,Handler

activityThread,Instrumentationinstrumentation,booleanregistered）{//创建

InnerReceiver【2.3.2】mIIntentReceiver=newInnerReceiver（this,!

registered）;

mReceiver=receiver;

mContext=context;

mActivityThread=activityThread;

mInstrumentation=instrumentation;

mRegistered=registered;

mLocation=new

IntentReceiverLeaked（null）;

mLocation.fillInStackTrace（）;

}2.3.2创建InnerReceiver

 finalstaticclassInnerReceiverextendsIIntentReceiver.Stub{finalWeakReference

LoadedApk.ReceiverDispatchermDispatcher;

finalLoadedApk.ReceiverDispatcher

mStrongRef;

InnerReceiver（LoadedApk.ReceiverDispatcherrd,booleanstrong）{

mDispatcher=newWeakReferenceLoadedApk.ReceiverDispatcher（rd）;

mStrongRef=

strong?

rd:

null;

}...}ReceiverDispatcher（广播分发者）有一个内部类InnerReceiver，

该类继承于IIntentReceiver.Stub。

显然，这是一个Binder服务端，广播分发者通过

rd.getIIntentReceiver（）可获取该Binder服务端对象InnerReceiver，用于BinderIPC通

 2.4AMP.registerReceiver[-ActivityManagerNative.java]

 publicIntentregisterReceiver（IApplicationThreadcaller,StringpackageName,

IIntentReceiverreceiver,IntentFilterfilter,Stringperm,intuserId）throws

RemoteException{Parceldata=Parcel.obtain（）;

Parcelreply=Parcel.obtain（）;

data.writeIn