如何将数据服务传递给活动？

Question

我有三节课

1.菜单活动

2.LocationUpdateService

3.多重标记器

1.菜单活动

@Override
    protected void onStart() {
        super.onStart();

        bindService(new Intent(this, LocationUpdatesService.class), mServiceConnection,
                Context.BIND_AUTO_CREATE);
    }

2、LocationUpdateService：（这是服务类）

   private  void sendMessageToActivity(Location l, String msg) {
        Intent intent = new Intent("GPSLocationUpdates");
        // You can also include some extra data.
        intent.putExtra("Status", msg);
        Bundle b = new Bundle();
        b.putParcelable("Location", l);
        intent.putExtra("Location", b);
        LocalBroadcastManager.getInstance(context).sendBroadcast(intent);
            Toast.makeText(context,"Sending Data to BroadCast Receiver",Toast.LENGTH_LONG).show();
    }

3、多重标记（活动）

 LocalBroadcastManager.getInstance(this).registerReceiver(
                mMessageReceiver, new IntentFilter("GPSLocationUpdates"));



 private BroadcastReceiver mMessageReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            // Get extra data included in the Intent
            String message = intent.getStringExtra("Status");
            Bundle b = intent.getBundleExtra("Location");

            Log.d("messagesshow","****** "+message);

           Location   lastKnownLoc = (Location) b.getParcelable("Location");
            if (lastKnownLoc != null) {

                Log.d("messagesshow","*****    "+String.valueOf(lastKnownLoc.getLatitude()));

            }

             Toast.makeText(context, "Data Receiver called", Toast.LENGTH_SHORT).show();
        }
    };

我的问题是：当我打开我的菜单活动我的Toast消息打印发送数据到广播接收器，然后点击按钮我调用MultipleMarker。我无法从服务中获取值。。。但当我按下后退按钮时，我重定向到MenuActivity，此时我得到了值。。。

我想将LocationUpdateservice类中的数据获取到MultipleMarker中。课堂活动。。。

Answer 1

您可以按照以下步骤创建接口并获取服务引用：

在LocationUpdateService中添加以下属性：

public class LocationUpdateService extends Service{

    // The Binder is an intern class
    public class LocalBinder extends Binder {
        //The Binder as a method which return the service
        public LocationUpdateService getService() {
            return LocationUpdateService.this;
        }
    }

    private final IBinder mBinder = new LocalBinder();

}   

然后在您的菜单活动中：

public class MenuActivity extends AppCompatActivity {
    private LocationUpdateService mService;

    // Connection interface to the service
    private ServiceConnection mConnection = new ServiceConnection() {

        // Called when the activity connects to the service
        public void onServiceConnected(ComponentName className, IBinder service) {

        // Here you get the Service
            mService = ((LocationUpdateService.LocalBinder)service).getService();

        }

        // Called when service is disconnected
        public void onServiceDisconnected(ComponentName className) {
            mService = null;
        }
    };
}

然后您的bindService（）方法将调用onServiceConnect（），您将获得Service的实例。

注意：onServiceConnect（）是异步调用的，因此您不能在调用bindService（）后立即使用Service的方法，因为您将有一个NullPointerException。