GPS启动流程.docxVIP

GPS启动流程及数据流向分析：?首先在系统init阶段，会通过ServiceManageraddService添加很多的Service，这其中就包含LocationService。代码在SystemServer.java中:? ? ? ? ? ? ?try?{??????????????????Slog.i(TAG,?Location?Manager);??????????????????location?=?new?LocationManagerService(context);??????????????????ServiceManager.addService(Context.LOCATION_SERVICE,?location);?????????????}?catch?(Throwable?e)?{??????????????????reportWtf(starting?Location?Manager,?e);?????????????}?随后调用LocationManagerService的systemReady函数开启一个线程。? ? ? ? ? ??final?LocationManagerService?locationF?=?location;????????????try?{?????????????????????if?(locationF?!=?null)?locationF.systemReady();?????????????????}?catch?(Throwable?e)?{?????????????????????reportWtf(making?Location?Service?ready,?e);????????????}--LocationManagerService.java? ? ?void?systemReady()?{??????????//?we?defer?starting?up?the?service?until?the?system?is?ready???????????Thread?thread?=?new?Thread(null,?this,?LocationManagerService);??????????thread.start();?????}在 Thread的run函数中为接收消息做好了准备，并且调用了一个initialize函数：? ? ?public?void?run()?????{??????????Process.setThreadPriority(Process.THREAD_PRIORITY_BACKGROUND);??????????Looper.prepare();??????????mLocationHandler?=?new?LocationWorkerHandler();??????????initialize();??????????Looper.loop();?????}接着看initialize()：private?void?initialize()?{??????????//?Create?a?wake?lock,?needs?to?be?done?before?calling?loadProviders()?below??????????PowerManager?powerManager?=?(PowerManager)?mContext.getSystemService(Context.POWER_SERVICE);??????????mWakeLock?=?powerManager.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK,?WAKELOCK_KEY);??????????//?Load?providers??????????loadProviders();??????????//?Register?for?Network?(Wifi?or?Mobile)?updates??????????IntentFilter?intentFilter?=?new?IntentFilter();??????????intentFilter.addAction(ConnectivityManager.CONNECTIVITY_ACTION);??????????//?Register?for?Package?Manager?updates??????????intentFilter.addAction(Intent.ACTION_PACKAGE_REMOVED);??????????intentFilter.addAction(Intent.ACTION_PACKAGE_RESTARTED