Why does Intent.createChooser() need a BroadcastReceiver and how to implement?

问题

The following snippet, called from my implementation of onOptionsItemSelected(), works nicely to carry the user from my app to a mail client with email address, subject and body pre-filled. I'm using this as a simple way to let the user give me feedback.

String uriText =
    "mailto:" + emailAddress +
    "?subject=" + subject +
    "&body=" + body;

Intent emailIntent = new Intent(Intent.ACTION_SENDTO, Uri.parse(uriText));
startActivity(Intent.createChooser(emailIntent, "Pick an email app:"));

When the mail app opens (on my Nexus S with Android 4.0.4), LogCat outputs the following, and I can't figure out why; Google and SO searches for createChooser unregisterReceiver seem fruitless, and I can't find many examples of createChooser() that also call unregisterReceiver() in a way that helps this situation.

04-08 21:26:19.094: E/ActivityThread(27894): Activity com.android.internal.app.ChooserActivity has leaked IntentReceiver com.android.internal.app.ResolverActivity$1@4150aac8 that was originally registered here. Are you missing a call to unregisterReceiver()?

04-08 21:26:19.094: E/ActivityThread(27894): android.app.IntentReceiverLeaked: Activity com.android.internal.app.ChooserActivity has leaked IntentReceiver com.android.internal.app.ResolverActivity$1@4150aac8 that was originally registered here. Are you missing a call to unregisterReceiver()?

04-08 21:26:19.094: E/ActivityThread(27894): at android.app.LoadedApk$ReceiverDispatcher.(LoadedApk.java:763)

This feels like an Android bug because my own code doesn't call registerReceiver(), so why is Android complaining that I need to call unregisterReceiver()?

回答1:

I see this as well on my Galaxy Nexus with 4.0.4, but only if there's only one option and the chooser doesn't appear.

This is a bug in Android source - not much you can do about it. Their ResolverActivity registers a BroadcastReceiver, but doesn't always unregister it.

More detail:

Intent.createChooser() will start a ResolverActivity. In onCreate(), the activity calls

mPackageMonitor.register(this, false);

mPackageMonitor is a BroadcastReceiver and within register() it registers itself on the activity. Normally, the receiver is unregistered in onStop(). However, later in onCreate() the code checks how many options the user can choose from. If there's only one it calls finish(). Since finish() is called in onCreate() the other lifecycle methods are never called and it jumps straight to onDestroy() - leaking the receiver.

I didn't see a bug for this in the Android issues database, so I created one.

For more info you can see this in code:

ResolverActivity
PackageMonitor

As a side note, Google uses email as an example of when you wouldn't want to use a chooser so you may consider just launching the intent normally. See the javadocs for Intent#ACTION_CHOOSER.

回答2:

Simple resolution of problem.

More info here: https://developer.android.com/training/basics/intents/sending.html

Uri location = Uri.parse("geo:0,0?q=1600+Amphitheatre+Parkway,+Mountain+View,+California");
Intent mapIntent = new Intent(Intent.ACTION_VIEW, location);

PackageManager pkManager = getPackageManager();
List<ResolveInfo> activities = pkManager.queryIntentActivities(mapIntent, 0);

if (activities.size() > 1) {
    // Create and start the chooser
    Intent chooser = Intent.createChooser(mapIntent, "Open with");
    startActivity(chooser);

  } else {
    startActivity( mapIntent );
}

来源：https://stackoverflow.com/questions/10068954/why-does-intent-createchooser-need-a-broadcastreceiver-and-how-to-implement

标签

android

android-intent

broadcastreceiver