哪个线程不与LocalBroadcastManager注册的BroacastReceiver运行的onReceive()? [英] On which thread does onReceive() of a BroacastReceiver registered with LocalBroadcastManager run?
问题描述
我注册了preference活动的广播接收器,并从(清醒)IntentService发送一个(同步)播出。很明显的onReceive运行服务的线程上。这是我的部分的错吗?难道是记录的行为?
I register a broadcast receiver in a preference activity and send it a (sync) broadcast from a (Wakeful) IntentService. Apparently onReceive runs on the service's thread. Is this a fault of my part ? Is it documented behavior ?
preference活动:
Preference activity:
public final class SettingsActivity extends BaseSettings {
private static CharSequence sMasterKey;
private CheckBoxPreference mMasterPref;
// Receiver
/** If the master preference is changed externally this reacts */
private BroadcastReceiver mExternalChangeReceiver =
new ExternalChangeReceiver();
public static void notifyMonitoringStateChange(Context ctx,
CharSequence action, boolean isToggling) {
final LocalBroadcastManager lbm = LocalBroadcastManager
.getInstance(ctx);
Intent intent = new Intent(ctx, ExternalChangeReceiver.class);
intent.setAction(action.toString());
intent.putExtra(TOGGLING_MONITORING_IN_PROGRESS, isToggling);
lbm.sendBroadcastSync(intent);
}
@Override
protected void onStart() {
super.onStart();
final LocalBroadcastManager lbm = LocalBroadcastManager
.getInstance(this);
lbm.registerReceiver(mExternalChangeReceiver, new IntentFilter(
ac_toggling.toString()));
}
@Override
protected void onStop() {
// may not be called in Froyo
final LocalBroadcastManager lbm = LocalBroadcastManager
.getInstance(this);
lbm.unregisterReceiver(mExternalChangeReceiver);
super.onStop();
}
private final class ExternalChangeReceiver extends BroadcastReceiver {
ExternalChangeReceiver() {}
@Override
@SuppressWarnings("synthetic-access")
public void onReceive(Context ctx, Intent intent) {
if (sMasterKey == null || mMasterPref == null) return; // if
// onPostReceive has not run this will be null
final String action = intent.getAction();
if (ac_toggling.equals(action)) {
final boolean isToggling = intent.getBooleanExtra(
TOGGLING_MONITORING_IN_PROGRESS, false);
Log.w(ExternalChangeReceiver.class.getSimpleName(),
"isToggling " + isToggling);
mMasterPref.setEnabled(!isToggling); // line 168 !!!
refreshMasterPreference(isToggling);
}
}
}
}
IntentService(LocationMonitor):
IntentService (LocationMonitor):
SettingsActivity.notifyMonitoringStateChange(this, ac_toggling, true);
异常(E / AndroidRuntime):
Exception (E/AndroidRuntime):
FATAL EXCEPTION: IntentService[LocationMonitor]
android.view.ViewRootImpl$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.
at android.view.ViewRootImpl.checkThread(ViewRootImpl.java:4746)
at android.view.ViewRootImpl.requestLayout(ViewRootImpl.java:823)
at android.view.View.requestLayout(View.java:15473)
at android.view.View.requestLayout(View.java:15473)
at android.view.View.requestLayout(View.java:15473)
at android.view.View.requestLayout(View.java:15473)
at android.view.View.requestLayout(View.java:15473)
at android.view.View.requestLayout(View.java:15473)
at android.view.View.requestLayout(View.java:15473)
at android.view.View.requestLayout(View.java:15473)
at android.view.View.requestLayout(View.java:15473)
at android.widget.AbsListView.requestLayout(AbsListView.java:1819)
at android.widget.AdapterView$AdapterDataSetObserver.onChanged(AdapterView.java:813)
at android.widget.AbsListView$AdapterDataSetObserver.onChanged(AbsListView.java:5958)
at android.database.DataSetObservable.notifyChanged(DataSetObservable.java:37)
at android.widget.BaseAdapter.notifyDataSetChanged(BaseAdapter.java:50)
at android.preference.PreferenceGroupAdapter.onPreferenceChange(PreferenceGroupAdapter.java:238)
at android.preference.Preference.notifyChanged(Preference.java:1099)
at android.preference.Preference.setEnabled(Preference.java:726)
at gr.uoa.di.monitoring.android.activities.SettingsActivity$ExternalChangeReceiver.onReceive(SettingsActivity.java:168)
at android.support.v4.content.LocalBroadcastManager.executePendingBroadcasts(LocalBroadcastManager.java:297)
at android.support.v4.content.LocalBroadcastManager.sendBroadcastSync(LocalBroadcastManager.java:278)
at gr.uoa.di.monitoring.android.activities.SettingsActivity.notifyMonitoringStateChange(SettingsActivity.java:54)
at gr.uoa.di.monitoring.android.services.Monitor.abort(Monitor.java:241)
at gr.uoa.di.monitoring.android.services.LocationMonitor.doWakefulWork(LocationMonitor.java:103)
at com.commonsware.cwac.wakeful.WakefulIntentService.onHandleIntent(WakefulIntentService.java:94)
at android.app.IntentService$ServiceHandler.handleMessage(IntentService.java:65)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.os.HandlerThread.run(HandlerThread.java:60)
在一个仿真器API 17
On an emulator API 17
推荐答案
sendBroadcastSync()
确实是从调用线程上运行(除非有一场比赛正在进行)。它的实施<一个href="https://android.googlesource.com/platform/frameworks/support/+/refs/heads/master/v4/java/android/support/v4/content/LocalBroadcastManager.java"相对=nofollow>应的:
sendBroadcastSync()
is indeed run on the thread it is called from (except if there is a race going on). Its implementation should be:
public void sendBroadcastSync(Intent intent) { // directly calls executePendingBroadcasts
if (sendBroadcast(intent)) {
executePendingBroadcasts();
}
}
比赛的一部分,我不知道关于通过 sendBroadcast()
呼叫若发现任何匹配的接收器(注册LBM此意图),它返回true,<进入EM>将消息发送到一个私人处理后的与主回路<关联/ EM> - 简称:
The race part I am not sure about enters via the sendBroadcast()
call which returns true if it found any matching receiver (registered with LBM for this intent), after sending a message to a private handler associated with the main loop - abbreviated:
@Override
public boolean sendBroadcast(Intent intent) {
synchronized (mReceivers) {
final String action = intent.getAction();
final ArrayList<ReceiverRecord> entries = mActions.get(action);
if (entries == null) return false; // no receivers for that action
ArrayList<ReceiverRecord> receivers = new ArrayList<ReceiverRecord>();
for (ReceiverRecord receiver : entries) {
if (receiver.broadcasting) continue;
// match the intent
int match = receiver.filter.match(action,
intent.resolveTypeIfNeeded(mAppContext.getContentResolver()),
intent.getScheme(), intent.getData(),
intent.getCategories(), "LocalBroadcastManager");
if (match >= 0) {
receivers.add(receiver);
receiver.broadcasting = true;
}
}
final int size = receivers.size();
if (size == 0) return false; // no receivers for this intent
for (int i = 0; i < size; i++) {
receivers.get(i).broadcasting = false;
}
mPendingBroadcasts.add(new BroadcastRecord(intent, receivers));
if (!mHandler.hasMessages(MSG_EXEC_PENDING_BROADCASTS)) {
mHandler.sendEmptyMessage(MSG_EXEC_PENDING_BROADCASTS);
}
return true;
}
}
其中:
mHandler = new Handler(context.getMainLooper()) {
@Override
public void handleMessage(Message msg) {
switch (msg.what) {
case MSG_EXEC_PENDING_BROADCASTS:
executePendingBroadcasts();
break;
default:
super.handleMessage(msg);
}
}
我不知道是否有可能是主线程和线程 sendBroadcastSync()
正在执行之间的竞争 - 这样的 executePendingBroadcasts()
将运行在主线程。如果没有,那么 executePendingBroadcasts()
运行线程 sendBroadcastSync
运行,并在<一个href="http://grep$c$c.com/file/repository.grep$c$c.com/java/ext/com.google.android/android/4.3_r2.1/android/support/v4/content/LocalBroadcastManager.java#297"相对=nofollow>直接调用接收器的的onReceive
I am not sure if there can be a race between the main thread and the thread sendBroadcastSync()
is executing - so the executePendingBroadcasts()
will run on the main thread. If not then executePendingBroadcasts()
runs on the thread sendBroadcastSync
is run and directly calls the onReceive of the receivers
总有一天我应该看看为什么(在executePendingBroadcasts)同步(mReceivers)
,而不是同步(mPendingBroadcasts)
。
One of these days I should look into why (in executePendingBroadcasts) synchronized(mReceivers)
and not synchronized(mPendingBroadcasts)
.
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