将活动实例传递给IntentService

Question

Im am trying to pass an instance of my activity to an intent service. The reason for this is the intent service does a lot of background server communication and if there is an network error or the server returns an error I want to display a pop up message.

When i create the service i use this

    Intent service = new Intent(this, SyncService.class);
    Bundle b2 = new Bundle();
    b2.putParcelable(StringsConfig.OBJECT_DELIVERABLES, objects);
    service.putExtras(b2);
    startService(service);

Is there a way to pass an instance of an Activity over to it. I also have a method inside the SyncService class that accept an Activity but i dont know how to create an instance of the sync service class, pass the activity over via the method, and then start the sync service.

Any help is appreciated.

Answer 1

Its not a great idea to pass an Activity instance to an Intent Service. If your long running Background Service needs to show a dialog message, you are much better off modelling it as an Intent.

Just do:

Intent dialogIntent = new Intent(getApplicationContext(), YourDialogActivity.class);
dialogIntent.putStringExtra(Constants.TITLE, "Your Dialog Title");
dialogIntent.putIntExtra(Constants.MESSAGE, R.string.yourErrorMessageId);
startActivity(dialogIntent);

That way, the service contract is a lot cleaner.

Answer 2

The recommended way for an IntentService to communicate to an activity is via BroadcastReceiver. Take a look at this example:

In the activity that you want your IntentService to communicate with, create a BroadcastReceiver that listens for a specific intent action (a String). Here my example is called batchProcessReceiver, and listens for the BATCH_PROCESS_RECEIVER action. BATCH_PROCESS_RECEIVER can be a public static constant in your Activity.

private BroadcastReceiver batchProcessReceiver = new BroadcastReceiver() {
    @Override public void onReceive(Context context, Intent intent) {
        if (intent.getAction().equals(BATCH_PROCESS_RECEIVER)) {
            // do what you need to do here
        }
    }
};

In your activity's onResume:

registerReceiver(batchProcessReceiver, new IntentFilter(BATCH_PROCESS_RECEIVER));

onPause:

unregisterReceiver(batchProcessReceiver);

Then at a point in your IntentService, you can do

sendBroadcast(new Intent(MyActivity.BATCH_PROCESS_RECEIVER));

to trigger the action you want to do in your activity.