How to unregister BroadcastReceiver

问题:

My app uses a BroadcastReceiver to get sms in this way:

SmsBR.java

public class SmsBR extends BroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent) {
        Bundle bundle = intent.getExtras();
        if (bundle != null) {
            Object[] pdus = (Object[])bundle.get("pdus");
            final SmsMessage[] messages = new SmsMessage[pdus.length];

            for (int i = 0; i < pdus.length; i++) {
                messages[i] = SmsMessage.createFromPdu((byte[])pdus[i]);
            }
            if (messages.length > 0)
                //doSomething();
            }
        }
    }
}

Manifest.xml

<application android:icon="@drawable/icon" android:label="@string/app_name">
    <activity android:name=".Activity" android:label="@string/app_name">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter> 
    </activity>

    <receiver android:name=".SmsBR">
        <intent-filter>
            <action android:name="android.provider.Telephony.SMS_RECEIVED"></action>
        </intent-filter>
    </receiver>
</application>    

In this way SmsBR is always ON. I want to register it when a service starts (onCreate()) and unregister it when the service is destroyed (onDestroy()). How can I do this?

回答1:

Edit:

For an Activity:

In order to register your broadcast receiver from within your app, first, remove the <receiver> tag from your AndroidManifest.xml file. Then, call registerReceiver(BroadcastReceiver receiver, IntentFilter filter) in your onResume(). Use unregisterReceiver(BroadcastReceiver receiver) in your onPause() to unregister the Broadcast receiver.

For a Service:

Remove the receiver tag from the manifest file. You can then register your Broadcast receiver with the same method in the onCreate() and unregister in the onDestroy().

EDIT: Sample Code:

public class MyActivity extends Activity {
  private final BroadcastReceiver mybroadcast = new SmsBR();

  public void onResume() {
    super.onResume();

    IntentFilter filter = new IntentFilter();
    filter.addAction("android.provider.Telephony.SMS_RECEIVED");
    registerReceiver(mybroadcast, filter);
  }

  public void onPause() {
    super.onPause();

    unregisterReceiver(mybroadcast);
  }
}

回答2:

onDestroy() is not guaranteed to be called. When you start Activity from Activty, onPause() and onStop() method called instead of onDestroy().

onDestroy() calls when you hit back button or call finish() method.

Hence, broadcast receiver should be registered in onStart() or onResume(), and unregister receiver in onPause() or onStop().

If you unregister receiver in onDestroy() method, it might cause a memory leak in App.

回答3:

First remove receiver tag from manifest, then: for service :

@Override
public void onCreate() {


    myReceiver = new SmsBR();
    IntentFilter filter = new IntentFilter();
    filter.addAction("android.intent.action.SMS_RECEIVED");// add any actions you want
    registerReceiver(myReceiver , filter);

 }

@Override
public void onDestroy() {
    super.onDestroy();
    if (myReceiver != null)
        unregisterReceiver(myReceiver);
}

for Activity:

public class MyActivity extends Activity {
  private final BroadcastReceiver mybroadcast = new SmsBR();

  public void onResume() {
    super.onResume();

    IntentFilter filter = new IntentFilter();
    filter.addAction("android.provider.Telephony.SMS_RECEIVED");
    registerReceiver(mybroadcast, filter);
  }

  public void onPause() {
    super.onPause();

    if (mybroadcast!= null)
       unregisterReceiver(mybroadcast);
  }
}