Question

我正在尝试将数据从服务传递到活动并更新列表视图。

服务：

public class mqtt_service extends Service {

final String serverUri = "tcp://192.xxx.x.xx:1883";
private static final String TAG = "MQTTService";
private static final String Topic = "test";
MqttAndroidClient client;

public mqtt_service() { }

@Override
public int onStartCommand(Intent intent, int flags, int startId)
{
    Log.i(TAG, "onStartCommand methode called");

    Runnable r = new Runnable() {
        @Override
        public void run() {

            initMqtt();
            Log.i(TAG, "start init");

            client.setCallback(new MqttCallback() {
                @Override
                public void connectionLost(Throwable cause) { }

                @Override
                public void messageArrived(String topic, MqttMessage message) throws Exception
                {
                   Toast.makeText(getApplicationContext(),"MQTT Message:\n" + new String(message.getPayload()), Toast.LENGTH_SHORT).show();

                    Intent done = new Intent();
                    done.setAction("mqttData");
                    String json = new String(message.getPayload());
                    done.putExtra("newData",json);
                    LocalBroadcastManager.getInstance(getApplicationContext()).sendBroadcast(done);
                }

                @Override
                public void deliveryComplete(IMqttDeliveryToken token) {

                }
            });
        }
    };

    Thread backgroundThread = new Thread(r);
    backgroundThread.start();
    return Service.START_STICKY;
}

  //unnecessary code here    

}

活动：

public class mainView extends AppCompatActivity {

private ListView datalist;
private CustomAdapter mAdapter;
ArrayList<Datamodel> list;
Gson gson;



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


    datalist = findViewById(R.id.datalistview);
    gson = new Gson();

    Intent i = new Intent(this, mqtt_service.class);
    startService(i);


    list = new ArrayList<>();
    list.add(new Datamodel("1", "12", "Number1","Number2", "Test"));
    list.add(new Datamodel("2", "20", "Teststring","testtext", "Name"));

    mAdapter = new CustomAdapter(this,R.layout.listview_item,list);
    datalist.setAdapter(mAdapter);

}

    BroadcastReceiver DataReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {

            String neuer = intent.getStringExtra("newData");
            Object object = gson.fromJson(neuer,Object.class);
            ArrayList<Datamodel> newData = (ArrayList<Datamodel>) object;
            list.addAll(newData);
            mAdapter.notifyDataSetChanged()
            //Update listview here????

        }
    };

@Override
protected void onResume() {
    // TODO Auto-generated method stub
    super.onResume();
    LocalBroadcastManager.getInstance(Stoermeldungen_mainView.this).registerReceiver(DataReceiver,new IntentFilter("mqttData"));

}
}

服务中的重要部分是messageArrived方法，从这里我将数据（数据是一个Json字符串）传递给活动。在活动中，我在BroadcastReceiver中接收数据，并将带有gson的Json字符串转换为原始数据（arraylist。最后，我将新数据添加到我的listview中，这是问题，它没有更新。也许有人可以给我一些指针

Mqtt将数据从服务传递到活动并更新列表视图

0 个答案: