android - 当应用程序在 android 中处于前台时，每 5 秒更新一次状态

Question

我想定期更新我在 firebase 中的在线状态，但当它在前台时，但当它在后台消失时，我必须将状态设置为离线。所以请帮助我如何管理。

这是我在 firebase 上更新它的代码

private void fireStoreUpdate() {
    PreferenceManager preferenceManager = new PreferenceManager(getApplicationContext());
    String chefId = preferenceManager.getChefId();
    String restuarantId = preferenceManager.getMerchantId();
    Restaurant restaurant = new Restaurant("online", String.valueOf(System.currentTimeMillis()), chefId, restuarantId);
    // Firestore
    FirebaseFirestore.getInstance().collection("restaurants").document("Restaurant ID : " + restuarantId).set(restaurant);
}

它正在更新，但我该如何让它每 5 秒重复一次？

Answer 1

您可以使用处理程序并每隔“x”次执行您的函数。当生命周期为 onPause() 时，您只需停止此处理程序，当应用程序在 onResume() 中返回前台时再次执行处理程序。

我将通过一个简单的 Activity 向您展示该方法

主要 Activity :

public class MainActivity extends AppCompatActivity {
    private final long EVERY_FIVE_SECOND = 5000;

    private Handler handler;
    private Runnable runnable;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        //Executing the handler
        executeHandler();
    }

    private void executeHandler(){
        //If the handler and runnable are null we create it the first time.
        if(handler == null && runnable == null){
            handler = new Handler();

           runnable = new Runnable() {
                @Override
                public void run() {
                    //Updating firebase store
                    fireStoreUpdate();
                    //And we execute it again
                    handler.postDelayed(this, EVERY_FIVE_SECOND);
                }
            };
        }
        //If the handler and runnable are not null, we execute it again when the app is resumed.
        else{
            handler.postDelayed(runnable, EVERY_FIVE_SECOND);
        }
    }

    @Override
    protected void onResume() {
        super.onResume();
        //execute the handler again.
        executeHandler();
    }

    @Override
    protected void onPause() {
        super.onPause();
        //we remove the callback
        handler.removeCallbacks(runnable);
        //and we set the status to offline.
        updateStatusToOffline();
    }
}

希望对您有所帮助。