Question

我有2个类，分别是GcmMessageHandler和Control（它是一个活动类，显示一些图形）。当我处理gcm消息时，我想刷新控件类（但如果它的前面）

public class GcmMessageHandler extends IntentService {

            String mes;
            private Handler handler;
            public GcmMessageHandler() {
                super("GcmMessageHandler");
            }

            @Override
            public void onCreate() {
                // TODO Auto-generated method stub
                super.onCreate();
                handler = new Handler();
            }
            @Override
            protected void onHandleIntent(Intent intent) {
               Bundle extras = intent.getExtras();

               GoogleCloudMessaging gcm = GoogleCloudMessaging.getInstance(this);
               // The getMessageType() intent parameter must be the intent you received
               // in your BroadcastReceiver.
               String messageType = gcm.getMessageType(intent);

               mes = extras.getString("title");
               showToast();
               Log.i("GCM", "Received : (" +messageType+")  "+extras.getString("title"));

               GcmBroadcastReceiver.completeWakefulIntent(intent);

            }

            public void showToast(){
                handler.post(new Runnable() {
                    public void run() {
                        if(mes.equals("Control")){

                        }else{
                            Toast.makeText(getApplicationContext(),mes , Toast.LENGTH_LONG).show();
                        }
                    }
                 });

            }
        }

在这部分：

if(mes.equals("Control")){ }

如果控制活动类是恢复的，我想刷新它。我怎么能这样做？

Answer 1

您可以使用BroadcastReceiver通知您的活动有关任何更改。因此，请先在您的活动中注册BroadcastReceiver：

public class MainActivity extends Activity {

    public static String REFRESH_ACTIVITY = "com.domain.action.REFRESH_UI"

    private BroadcastReceiver broadcastReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            // do UI updates
        }
    };

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

        // do UI updates

        IntentFilter filter = new IntentFilter();
        filter.addAction(REFRESH_ACTIVITY);
        this.registerReceiver(broadcastReceiver, filter);
    }

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

        this.unregisterReceiver(broadcastReceiver);
    }

    ...
}

然后发送广播以从任何位置执行UI更新：

if (mes.equals("Control")) { 
    Intent intent = new Intent();
    intent.setAction(MainActivity.REFRESH_ACTIVITY);

    sendBroadcast(intent);
}

Answer 2

也许你可以使用观察者设计模式。让GcmMessageHandler将Control活动作为观察者保存，然后在需要时通知它。

public class GcmMessageHandler extends IntentService {

        String mes;
        private Handler handler;
        private Control mObserver

        public GcmMessageHandler() {
            super("GcmMessageHandler");
        }

        public void attachObserver(Control ctrl) {
            mObserver = ctrl;
        }

然后，您只需向Control类中添加一个可以从GcmMessageHandler类调用的方法。

   if(mes.equals("Control")){
           mObserver.update(); // example
                        }else ...

如果你第一次定义一个观察者界面，它会更光滑：

public interface IObserver {
    public abstract void update();
}

让你的Control类实现它。这样，您的GcmMessageHandler类可以有一个观察者列表：

   public class GcmMessageHandler extends IntentService {

        String mes;
        private Handler handler;
        private List<IObserver> mObservers;

        public GcmMessageHandler() {
            super("GcmMessageHandler");
        }

        @Override
        public void onCreate() {
            // TODO Auto-generated method stub
            super.onCreate();
            handler = new Handler();
            mObservers = new ArrayList<IObserver>();
        }

        public void attachObserver(Control ctrl) {
            mObservers.add(ctrl);
        }
        private void notify() {
         for(IObserver observer : mObservers) 
            observer.update();
        }

当然，如果Control类是持有GcmMessageHandler对象的那个，你只需从Control调用attach方法，就像这样：

myGcmMessageHandler.attachObserver(this);

通知活动类

2 个答案: