Android应用程序启动过程源代码分析（3）这个函数定义在frameworks/base/core/java/android/app/ActivityThread.java文件中：publicfinalclassActivityThread{......privatefinalvoidhandlePauseActivity(IBindertoken,booleanfinished,booleanuserLeaving,intconfigChanges){ActivityClientRecordr=mActivities.get(token);if(r!=null){//Slog.v(TAG,"userLeaving="+userLeaving+"handlingpauseof"+r);if(userLeaving){performUserLeavingActivity(r);}r.activity.mConfigChangeFlags|=configChanges;Bundlestate=performPauseActivity(token,finished,true);//Makesureanypendingwritesarenowcommitted.QueuedWork.waitToFinish();//Telltheactivitymanagerwehavepaused.try{ActivityManagerNative.getDefault().activityPaused(token,state);}catch(RemoteExceptionex){}}}......}函数首先将Binder引用token转换成ActivityRecord的远程接口ActivityClientRecord，然后做了三个事情：1.如果userLeaving为true，则通过调用performUserLeavingActivity函数来调用Activity.onUserLeaveHint通知Activity，用户要离开它了；2.调用performPauseActivity函数来调用Activity.onPause函数，我们知道，在Activity的生命周期中，当它要让位于其它的Activity时，系统就会调用它的onPause函数；3.它通知ActivityManagerService，这个Activity已经进入Paused状态了，ActivityManagerService现在可以完成未竟的事情，即启动MainActivity了Step17.ActivityManagerProxy.activityPaused这个函数定义在frameworks/base/core/java/android/app/ActivityManagerNative.java文件中：classActivityManagerProxyimplementsIActivityManager{......publicvoidactivityPaused(IBindertoken,Bundlestate)throwsRemoteException{Parceldata=Parcel.obtain();Parcelreply=Parcel.obtain();data.writeInterfaceToken(IActivityManager.descriptor);data.writeStrongBinder(token);data.writeBundle(state);mRemote.transact(ACTIVITY_PAUSED_TRANSACTION,data,reply,0);reply.readException();data.recycle();reply.recycle();}......}这里通过Binder进程间通信机制就进入到ActivityManagerService.activityPaused函数中去了。Step18.ActivityManagerService.activityPaused这个函数定义在frameworks/base/services/java/com/android/server/am/ActivityManagerService.java文件中：publicfinalclassActivityManagerServiceextendsActivityManagerNativeimplementsWatchdog.Monitor,BatteryStatsImpl.Batter