将数据从服务传输到活动答案

【问题标题】：Tranfer Data from service to activity将数据从服务传输到活动
【发布时间】：2020-12-05 19:39:17
【问题描述】：

当用户杀死应用程序时，我的服务正在后台运行。它有一个按钮，我可以返回到地图活动。但是，当用户在销毁应用程序后通过通知按钮返回应用程序时，地图已创建，但我从服务传输到地图活动的信息为空。

当用户没有杀死应用并通过通知按钮返回时，数据存在。

这是我的代码：

//Map Activity

        //OnPause = transfer the data to service intent(Working fine)

        BackgroundLocation backgroundLocation = new BackgroundLocation();
        mServiceIntent = new Intent(this, backgroundLocation.getClass());

        if (!isMyServiceRunning(backgroundLocation.getClass())) {

            mServiceIntent.putExtra("AddressBackgound",mAddress);
            mServiceIntent.putExtra("AddressLatBackgound",destinationLat);
            mServiceIntent.putExtra("AddressLngBackgound",destinationLng);

            startService(mServiceIntent);
        }


           // OnMapReady = Getting the data from service intent(return null for all data)

            if (myLocation != null) {

                BackgroundLocation backgroundLocation = new BackgroundLocation();
                mServiceIntent = new Intent(this, backgroundLocation.getClass());

                Bundle extras = getIntent().getExtras();

                if (isMyServiceRunning(backgroundLocation.getClass()) && extras != null) {

                    String mAddress2 = extras.getString("AddressBackgound22");
                    Double destinationLat2 = extras.getDouble("AddressLatBackgound22");
                    Double destinationLng2 = extras.getDouble("AddressLngBackgound22");

                    Log.e("onResume", "onResume stats");
                    Log.e("Address", "" + mAddress2);
                    Log.e("Lat", String.valueOf(destinationLat2));
                    Log.e("Lng", String.valueOf(destinationLng2));

                    Log.e("OnMapReady","Service is running....");

                }
                else{

                     Log.e("OnMapReady","Service is not running");

                }
          }

Background Location(Service Intent) = 从 MapsActivity 获取信息并将信息返回给 MapsActivity。

//Service Intent 

// OnStartCommand



        Bundle extras = intent.getExtras();

        if (extras != null) {

//getting the data to the service is working fine even when the app killed the service still working with the data.

            mAddress = extras.getString("AddressBackgound");
            destinationLat = extras.getDouble("AddressLatBackgound");
            destinationLng = extras.getDouble("AddressLngBackgound");


            //This is what I am trying to send to MapsActivity:

            extras.putString("AddressBackgound22",mAddress);
            extras.putDouble("AddressLatBackgound22",destinationLat);
            extras.putDouble("AddressLngBackgound22",destinationLng);


            Log.e("onStartCommand", "onStartCommand started");

            Log.e("Address","" + mAddress);
            Log.e("Lat",  "" + destinationLat);
            Log.e("Lng",  "" + destinationLng);


        }

感谢您的宝贵时间。

【问题讨论】：

标签： java android android-studio service android-lifecycle

【解决方案1】：

有很多方法，我说一些：

1-在服务中使用存储数据（例如SharedPrefrences，DB和...）并在活动中检索

2-使用事件总线或广播接收器

3-使用回调模式将数据从服务回调到活动

【讨论】：

【解决方案2】：

多亏了@Mohammadreza，我在服务意图上使用了 sharedPref 并成功了。

这就是我所做的：

       public static final String MY_PREFS_NAME = "MyData";

//保存SharedPref(BackgroundActivity):

        SharedPreferences.Editor editor = getSharedPreferences(MY_PREFS_NAME, MODE_PRIVATE).edit();
        editor.putString("AddressBackgound",mAddress);
        editor.putString("AddressLatBackgound", String.valueOf(destinationLat));
        editor.putString("AddressLngBackgound", String.valueOf(destinationLng));
        editor.apply();

//读取 SharedPref(MapsActivity):

            SharedPreferences prefs = getSharedPreferences(BackgroundLocation.MY_PREFS_NAME, MODE_PRIVATE);

BackgroundLocation backgroundLocation = new BackgroundLocation();

            if (isMyServiceRunning(backgroundLocation.getClass()) && prefs != null ) {


                 String mAddress = prefs.getString("AddressBackgound","mAddress");
                 Double UserStartLocationLat = Double.parseDouble(String.valueOf(Double.valueOf(prefs.getString("UserStartLocationLat", "UserStartLocationLatNull"))));
                 Double UserStartLocationLng = Double.parseDouble(String.valueOf(Double.valueOf(prefs.getString("UserStartLocationLng", "UserStartLocationLngNull"))));

             }

isMyServiceRunning：

private boolean isMyServiceRunning(Class<?> serviceClass) {
    ActivityManager manager = (ActivityManager) getSystemService(Context.ACTIVITY_SERVICE);
    for (ActivityManager.RunningServiceInfo service : manager.getRunningServices(Integer.MAX_VALUE)) {
        if (serviceClass.getName().equals(service.service.getClassName())) {
            Log.i ("Service status", "Running");
            return true;
        }
    }
    Log.i ("Service status", "Not running");
    return false;
}

【讨论】：

【解决方案3】：

您可以使用事件总线或广播接收器将数据从服务发送到活动/片段

【讨论】：

欢迎来到 SO。通常会发送更多有用的信息，例如要使用的图书馆链接或文章。