Activity中bindService和registerReceiver的清理工作[通俗易懂]

大家好，又见面了，我是你们的朋友全栈君。

在Android开发中，我们经常需要注册BroadcastReceiver和bind service。

接口函数如下：

public Intent registerReceiver(BroadcastReceiver receiver, IntentFilter filter);

public void unregisterReceiver(BroadcastReceiver receiver);

public boolean bindService(Intent service, ServiceConnection conn, int flags);

public void unbindService(ServiceConnection conn);

有的时候，用户只调用了注册函数，或者是bind service，而忘记了unregisterReceiver和unbindService。这时，在Activity退出的时候，会自动这些问题，自动调用unregisterReceiver和unbindService。具体的流程如下：

private void handleDestroyActivity(IBinder token, boolean finishing, int configChanges, boolean getNonConfigInstance) { ActivityClientRecord r = performDestroyActivity(token, finishing, configChanges, getNonConfigInstance); 回调Activity的onDestroy if (r != null) { // Mocked out contexts won’t be participating in the normal // process lifecycle, but if we’re running with a proper // ApplicationContext we need to have it tear down things // cleanly. Context c = r.activity.getBaseContext(); if (c instanceof ContextImpl) { ((ContextImpl) c).scheduleFinalCleanup( r.activity.getClass().getName(), “Activity”); 清理 注册的receiver和bind的service } } if (finishing) { try { ActivityManagerNative.getDefault().activityDestroyed(token); 通知AMS，activity已经destroy } catch (RemoteException ex) { // If the system process has died, it’s game over for everyone. } } mSomeActivitiesChanged = true; }

In ContextImpl.java

final void scheduleFinalCleanup(String who, String what) { mMainThread.scheduleContextCleanup(this, who, what); }

In ActivityThread.java

final void scheduleContextCleanup(ContextImpl context, String who, String what) { ContextCleanupInfo cci = new ContextCleanupInfo(); cci.context = context; cci.who = who; cci.what = what; sendMessage(H.CLEAN_UP_CONTEXT, cci); }

case CLEAN_UP_CONTEXT: ContextCleanupInfo cci = (ContextCleanupInfo)msg.obj; cci.context.performFinalCleanup(cci.who, cci.what); break;

In ContextImpl.java

final void performFinalCleanup(String who, String what) { //Log.i(TAG, “Cleanup up context: ” + this); mPackageInfo.removeContextRegistrations(getOuterContext(), who, what); }

In LoadedApk.java

public void removeContextRegistrations(Context context, String who, String what) { final boolean reportRegistrationLeaks = StrictMode.vmRegistrationLeaksEnabled(); ArrayMap<BroadcastReceiver, LoadedApk.ReceiverDispatcher> rmap = mReceivers.remove(context); if (rmap != null) { for (int i=0; i<rmap.size(); i++) { 清理所有已经注册的receiver LoadedApk.ReceiverDispatcher rd = rmap.valueAt(i); IntentReceiverLeaked leak = new IntentReceiverLeaked( what + ” ” + who + ” has leaked IntentReceiver “ + rd.getIntentReceiver() + ” that was ” + “originally registered here. Are you missing a ” + “call to unregisterReceiver()?”); leak.setStackTrace(rd.getLocation().getStackTrace()); Slog.e(ActivityThread.TAG, leak.getMessage(), leak); if (reportRegistrationLeaks) { StrictMode.onIntentReceiverLeaked(leak); } try { ActivityManagerNative.getDefault().unregisterReceiver( rd.getIIntentReceiver()); } catch (RemoteException e) { // system crashed, nothing we can do } } } mUnregisteredReceivers.remove(context); //Slog.i(TAG, “Receiver registrations: ” + mReceivers);

ArrayMap<ServiceConnection, LoadedApk.ServiceDispatcher> smap = mServices.remove(context); if (smap != null) { for (int i=0; i<smap.size(); i++) { 解绑定已经bind的service LoadedApk.ServiceDispatcher sd = smap.valueAt(i); ServiceConnectionLeaked leak = new ServiceConnectionLeaked( what + ” ” + who + ” has leaked ServiceConnection “ + sd.getServiceConnection() + ” that was originally bound here”); leak.setStackTrace(sd.getLocation().getStackTrace()); Slog.e(ActivityThread.TAG, leak.getMessage(), leak); if (reportRegistrationLeaks) { StrictMode.onServiceConnectionLeaked(leak); } try { ActivityManagerNative.getDefault().unbindService( sd.getIServiceConnection()); } catch (RemoteException e) { // system crashed, nothing we can do } sd.doForget(); } } mUnboundServices.remove(context); //Slog.i(TAG, “Service registrations: ” + mServices); }

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