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事情是这样的，我的应用程序有一个服务（扩展服务）负责建立套接字连接并使用 firebase 原生 android 框架监听传入的网络流量。这是它的样子

public class SocketService extends Service {

private Firebase firebase;

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

    firebase = AppHelper.getInstance().getFirebase().child(AppHelper.getInstance().getFirebase().getAuth().getUid());
    AppHelper.getInstance().categoriesController.setListeners(firebase.child("categories"));
    AppHelper.getInstance().tablesController.setListeners(firebase.child("tables"));
    AppHelper.getInstance().itemsController.setListeners(firebase.child("items"));
    AppHelper.getInstance().requestsController.setListeners(firebase.child("requests"));
    AppHelper.getInstance().ordersController.setListeners(firebase.child("orders"));
}

@Override
public IBinder onBind(Intent intent) {
    return null;
}

@Override
public int onStartCommand(Intent intent, int flags, int startId) {
    return START_NOT_STICKY;
}

@Override
public void onDestroy() {
    super.onDestroy();
    AppHelper.getInstance().categoriesController.removeListeners(firebase.child("categories"));
    AppHelper.getInstance().tablesController.removeListeners(firebase.child("tables"));
    AppHelper.getInstance().itemsController.removeListeners(firebase.child("items"));
    AppHelper.getInstance().ordersController.removeListeners(firebase.child("orders"));
    AppHelper.getInstance().requestsController.removeListeners(firebase.child("requests"));
    AppHelper.getInstance().clearUserData();
    AppHelper.getInstance().waiter = null;
    AppHelper.getInstance().setConnectionState(false);
}
}

如您所见，onStartCommand 返回 START_NOT_STICKY，因此服务不会在我离开应用程序后立即被终止（在后台 - 中间按钮上）

以下是 AppHelper 的工作原理：

public class AppHelper extends Application {

private static AppHelper instance = null;
private static Bus bus;
public TablesController tablesController;
public OrdersController ordersController;
public ItemsController itemsController;
public RequestsController requestsController;
public CategoriesController categoriesController;
private Firebase firebase;
public Waiter waiter;
private boolean connected = false;
public static AppHelper getInstance() {
    return instance;
}
public Bus getBus() {return bus;}

@Override
public void onCreate() {
    super.onCreate();
    instance = this;
    bus = new Bus();
    tablesController = new TablesController(this);
    ordersController = new OrdersController(this);
    itemsController = new ItemsController(this);
    requestsController = new RequestsController(this);
    categoriesController = new CategoriesController(this);

    Firebase.setAndroidContext(this);
    firebase = new Firebase("https://restapp.firebaseio.com/");
    // other setup code
}

public Firebase getFirebase() {
    return firebase;
}

public void clearUserData() {
    tablesController.clearData();
    ordersController.clearData();
    itemsController.clearData();
    requestsController.clearData();
    categoriesController.clearData();
}

public void setConnectionState(boolean connected) {
    this.connected = connected;
    bus.post(new NetworkStateEvent(connected));
}

public boolean isConnected() {
    return connected;
}
}

每个控制器向相应节点注册一个 firebase 侦听器，这是基类的外观

public abstract class BaseController<T> {
protected Handler handler;
protected Firebase node;
protected ArrayList<T> models = new ArrayList<>();
protected ChildEventListener eventListener;

public BaseController(Context context) {
    handler = new Handler(context.getMainLooper());
    eventListener = getEventListener();
}

public void setListeners(Firebase node) {
    this.node = node;
    node.addChildEventListener(eventListener);
}

abstract ChildEventListener getEventListener();

public void removeListeners(Firebase node) {
    models.clear();
    node.removeEventListener(eventListener);
}

public ArrayList<T> getItems() {
    return models;
}

public void clearData() {
    models.clear();
}
}

所以，这就是发生的事情。一切都很好，如果您将应用程序留在后台并返回它仍然可以工作，您甚至可以启动其他应用程序，锁定设备等。但是，如果您将应用程序留在后台足够长的时间（10 分钟左右），当您回来firebase不会响应。该应用程序不会崩溃，但它什么也不做，就像它处于离线状态一样。我猜有些东西正在被收集起来。但我不知道那可能是什么。

我试过这个

connectedRef = new Firebase("https://restapp.firebaseio.com/.info/connected");

    connectionStateListener = new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot snapshot) {
            boolean connected = snapshot.getValue(Boolean.class);
            AppHelper.getInstance().setConnectionState(connected);
        }

        @Override
        public void onCancelled(FirebaseError error) {
            System.err.println("Listener was cancelled");
        }
    };
    connectedRef.addValueEventListener(connectionStateListener);

并在 firebase 断开连接时在用户的片段上显示一条消息。当我在 10 分钟后回到应用程序时，这条消息不存在（那个 firebase 已连接？）。

先感谢您！。

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