Passing data from a BroadcastReceiver to MainActivity works correctly only once
I have a PushNotificationReceiver (extends BroadcastReceiver)
and MainActivity
. The receiver sends some data (for example string value "New value
") to the MainActivity
via an Intent
. Then MainActivity
updates its TextView
with this value.
This works fine until I change this TextView
value to some other value (for example reset it to "UNSPECIFIED
") and move the activity to background and to foreground again. The MainActivity
is restored and its TextView
contains "New value
", however I expected it to be "UNSPECIFIED
" - this is the problem.
What is wrong with my app?
The whole proto project may be downloaded here.
Here is my MainActivity code
private TextView tvValue;
private EditText etNewValue;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
tvValue = (TextView)findViewById(R.id.value);
etNewValue = (EditText)findViewById(R.id.new_value);
findViewById(R.id.reset).setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
tvValue.setText(getResources().getString(R.string.not_specified));
}
});
findViewById(R.id.send_notification).setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
sendNotification(etNewValue.getText().toString());
}
});
processDataFromBroadcast(getIntent());
}
@Override
public void onNewIntent(Intent intent) {
super.onNewIntent(intent);
processDataFromBroadcast(intent);
}
private void sendNotification(String value){
NotificationManager mNotificationManager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
String title = "Proto App Notif";
Notification notification = new Notification(
android.R.drawable.ic_notification_overlay,
title,
System.currentTimeMillis());
notification.flags |= Notification.FLAG_AUTO_CANCEL;
Context ctxApp = getApplicationContext();
Intent notificationIntent = new Intent()
.setAction(PushNotificationReceiver.ACTION_NOTIFICATION)
.putExtra("value", value);
PendingIntent contentIntent = PendingIntent.getBroadcast(
ctxApp,
0,
notificationIntent,
PendingIntent.FLAG_UPDATE_CURRENT);
notification.setLatestEventInfo(
ctxApp,
title,
value,
contentIntent);
notification.audioStreamType = AudioManager.STREAM_NOTIFICATION;
mNotificationManager.notify(1, notification);
}
private void processDataFromBroadcast(Intent intent) {
if (!intent.hasExtra("value")){
return;
}
String val = intent.getStringExtra("value");
tvValue.setText(val); // Updating my activity look
}
PushNotificationReceiver
private static final String LOG_CAT = "PushNotificationReceiver";
static final String ACTION_NOTIFICATION = "com.mobiwolf.proto.NOTIFICATION_RECEIVER";
@Override
public void onReceive(Context context, Intent intent) {
if (!intent.getAction().equals(ACTION_NOTIFICATION)) {
return;
}
String value = intent.getStringExtra("value");
Log.d(LOG_CAT, "Received notification message: "+value); // Log always contains the value sent on first time
Intent i = new Intent();
i.setClass(context, MainActivity.class);
i.putExtra("value", value);
i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
context.startActivity(i);
}
And manifest
<receiver android:name="com.mobiwolf.proto.PushNotificationReceiver">
<intent-filter>
<action android:name="com.mobiwolf.proto.NOTIFICATION_RECEIVER" />
</intent-filter>
</receiver>
<activity android:name=".MainActivity"
android:label="@string/app_name"
android:launchMode="singleTask">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
开发者_如何学C </activity>
Replace
i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
by
i.setFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP |
Intent.FLAG_ACTIVITY_CLEAR_TOP | Intent.FLAG_ACTIVITY_NEW_TASK);
For solving this problem I added global static trigger
/**
* This class triggers whether pushnotification was handled by MainActivity
* (Preventing handling this push notification twice when the MainActivity
* is moved to background and restored from background
*/
public final class PushNotifHandledTrigger {
private static boolean handled = true;
public static boolean wasHandled(){
return handled;
}
public static void set(){
handled = true;
}
public static void reset(){
handled = false;
}
}
Then before startActivity I do reset this trigger and set after handling (and of course perform handling only if trigger is not set)
Define a public static boolean newUpdate;
variable, set it to true
right before context.startActivity(i);
. Then, when in your MainActivity
you check to see the intent has extra
with it, also verify that newUpdate
is true
, and if it is, reset it to false
and update your TextView
field. The last function will look like this
private void processDataFromBroadcast(Intent intent) {
if ( !intent.hasExtra("value") || (newUpdate == false) ){ //So only new updates are processed.
return;
}
newUpdate = false; //This action will not be repeated unless another notification arrives
String val = intent.getStringExtra("value");
tvValue.setText(val); // Updating my activity look
}
精彩评论