Monday, April 9, 2012

Broadcast receiver - a change in flow since API 3.1

Prior to API 3.1 we could have a broadcast receiver which could have been invoked by an implicit intent even if the application to which it belonged was in stopped state.

But this posed a security threat. Hence Google made it mandatory that for any broadcast receiver to receive an intent, there should be an activity and the application should not be in stopped state. Here is the link for further reading.

When an application is launched, it is in stopped state and hence it mandates the user to activate the application which has the broadcast receiver. If the application is force stopped by the user, then again the broadcast receiver fails to receive the intent. Hence apk having only broadcast receiver and developed on version prior to 3.1 will no longer work for later versions. 

However one can make use of FLAG_INCLUDE_STOPPED_PACKAGES to activate components in stopped application. This will not require creation of another activity in order to use the broadcast receiver. 
 Intent intent = new Intent("com.custom.intent"); intent.addFlags(Intent.FLAG_INCLUDE_STOPPED_PACKAGES); 
this.sendBroadcast(intent);

The other way as I had mentioned earlier would be to write an activity which may or may not be a launcher activity. 
PackageManager pm = getPackageManager(); 
Intent appStartIntent = 
pm.getLaunchIntentForPackage("com.your.broadcast.receiver.package");
if (null != appStartIntent)
 startActivity(appStartIntent);
 }

If it is not a launcher app, then you need to mention the the category as INFO in the intent-filter in the manifest file of the broadcast receiver. 
This is a sample manifest file:

   <application
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name" 
        android:theme="@android:style/Theme.Black.NoTitleBar.Fullscreen" >
       <activity
            android:name=".InvokedActivity"
            android:label="@string/app_name"
>
            <intent-filter
>
                <action android:name="android.intent.action.MAIN" /
>
                         
               <category android:name="android.intent.category.INFO" /
 >
<-- If the activity is a launcher then mention this instead 
             <category android:name="android.intent.category.LAUNCHER" /
                             >
 --
>

             </intent-filter
 >
        </activity
 >
       <receiver android:name=".TestBroadCastReceiver"
 >
           <intent-filter
 >
           <action android:name="com.custom.intent"
 >
          </action
 >
        </intent-filter
 >
       </receiver
 >
<application
 >
    
              
Here is the code for BroadCastReceiver:

public class TestBroadCastReceiver extends BroadcastReceiver 
 private static final String CUSTOM_INTENT = "com.custom.intent";
 public void onReceive(Context context, Intent intent) {
 if (intent.getAction().equals(CUSTOM_INTENT)) {
 //your code here } 
 }
 } 

 The code for InvokedActivity:

  public class InvokedActivity extends Activity { 
 public void onCreate(Bundle b) { 
 super.onCreate(b); 
 /*Toast.makeText(this, "starting xyz receiver...blah blah :)", Toast.LENGTH_LONG) .show();*/ finish();
 } 
}

6 comments:

  1. Hello Ashimita,
    this is Paresh, javacodegeeks members same as you, as i found yourself being a blogger and active in writing good stuffs for Android, i would like to invite you at TechnoTalkative.com, where right now i am doing alone, but my aim is to create a great team doing for Android community.

    please let me know if you want to be a part of my dream team.

    ReplyDelete
  2. Hello Paresh,

    Thanks for your appreciation. Sure I would like to write whenever I am free and have something to share with the community.
    Also, you are doing an excellent job with your site, TechnoTalkative.com. Will be glad to be a part of your community. :)

    Thanks,

    Ashimita

    ReplyDelete
  3. Hello, Could you please share me the full code of that same.

    ReplyDelete
    Replies
    1. I have not maintained this code in the repository. If you could share your email id, I can send you the code.

      Delete
  4. Hello, Could you please share me the full code

    ReplyDelete
  5. It has been a long time, since I had written this and I don't remember it storing. The code was trivial and I think if you can google around, you will get a lot of program samples. I will try to see, if I can find it somewhere in my pc.

    ReplyDelete