分开的活动，意图服务和广播接收器

Question

Assuming we've got an activity, an intentservice and a broadcastreceiver in our project all separated in different java files. Can anybody extendedly explain a scenario that the intentservice gets GCM push messages, the broadcastreceiver informs the activity about the incoming message and the activity instantly shows the message through a text box? Thank you in advance.

Answer 1

This is how to do it.

Step 1 Create a base activity and all other activities should extend it.

Step 2 In your custom application (say MyApplication.class ) class add these four methods and two variables

private static boolean activityVisible = false;
private static Context activityOnTop = null;

public static boolean isActivityVisible() {
    return activityVisible;
}

public static Context getActivityOnTop(){
    return activityOnTop;
}

public static void activityResumed(Context classContext) {
    activityVisible = true;
    activityOnTop = classContext;
}

public static void activityPaused() {
    activityVisible = false;
}

Step 3 In the base activity (which all other are extending) do this

@Override
protected void onResume() {
    super.onResume();
    MyApplication.activityResumed(this);
}

@Override
protected void onPaused() {
    super.onPaused();
    MyApplication.activityPaused(this);
}

Step 4 In your broadcast receiver when you get the notification event do this

if(!MyApplication.isActivityVisible()){
    //Show notification when app is not visible to user
    return;
}
Context currContext = MyApplication.getActivityOnTop();
if(currContext == null)
    return;
String currentActivity = currContext.getClass().getName();
if(!Strings.isNullOrEmpty(currentActivity)) {
    try {
        Intent i = new Intent(context, Class.forName(currentActivity));
        i.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_SINGLE_TOP);
        // Add the push notification message in the bundle here
        context.startActivity(i);
    }
    catch (ClassNotFoundException e){
    }
}

Step 5 In your base activity do this

@Override
protected void onNewIntent(Intent intent) {
    super.onNewIntent(intent);
    //get push notification message in the bundle here and show the dialog
    // DO NOT USE getIntent() here. USE THE intent THAT IS PASSED AS PARAMETER
}

NOTE:

Strings.isNullOrEmpty() is just a method I have created as a utility function