在Android上通过蓝牙读取信息

Question

I hope my question is not repeated at all, i tried reading another people that asks for similar information but couldnt fix my problem.

The thing here is that i have an android app that uses bluetooth , i have succesfully set the connection , i know that my app is sending a message when it gets connected to another device, but the problem here is that when i receive a message i would like to make it appear in a text view , or in a toast , but it is not reading properly.

Hope you guys can help me ill give you my code

package com.example.cesar.drcarobd2;



public class MainActivity extends AppCompatActivity implements SensorEventListener, AdapterView.OnItemClickListener {

private static final int CONEXION_EXITOSA = 0 ;
private static final int MESSAGE_READ = 1;
public static final int VELOCIDAD_ESCRITO = 2;
private static final int RPM_ESCRITO = 3 ;
// device sensor manager
private SensorManager mSensorManager;
ArrayAdapter<String> listAdapter;
ListView listView;
TextView brujula;
TextView velocidad;
BluetoothAdapter btAdapter; //creas un Adaptador bluetooth
Set<BluetoothDevice> ArregloDispositivos;
ArrayList<String> dispositivosApareados;
ArrayList<BluetoothDevice> dispositivos;
IntentFilter filtro;
BroadcastReceiver receptor;
private ArrayAdapter<String> Adapterdeconversacion;
String tag = "debugging";
public static final UUID MY_UUID = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB") ;  //UUID de conexion bt
Handler mhandler = new Handler(){


    @Override
    public void handleMessage(Message msg){
        ConnectedThread threadEscritura = new ConnectedThread((BluetoothSocket)msg.obj);
       // threadEscritura.run();
       // ConnectedThread threadConectado = new ConnectedThread((BluetoothSocket)msg.obj);
        Log.i(tag, "en el handler");
       // threadConectado.run();
        super.handleMessage(msg);
        switch(msg.what){
            case CONEXION_EXITOSA:
                    //Hacer algo
                Toast.makeText(getApplicationContext(), "Conexión", Toast.LENGTH_SHORT).show();
                Log.i(tag, "Conectado");
                String s = "Conectado Satisfactoriamente ";
                threadEscritura.write(s.getBytes());
                Log.i(tag, "Mensaje de Conexion Enviado");
               // threadConectado.run();
                break;
            case MESSAGE_READ:
                byte[] bufferleido = (byte[])msg.obj;
                String texto = new String(bufferleido);
                System.out.println(texto);
                Toast.makeText(getApplicationContext(), texto, Toast.LENGTH_SHORT).show();
                Log.i(tag, "Haciendo el Toast");
                velocidad.setText(texto);
                Log.i(tag, "Haciendo el Texto");
            case VELOCIDAD_ESCRITO:
                String mensajeVelocidad = "010D" + '\r';
                threadEscritura.write(mensajeVelocidad.getBytes());
                Log.i(tag, "Enviando Mensaje Velocidad");
                break;
            case RPM_ESCRITO:
                String mensajeRPM = "010C" + '\r';
                threadEscritura.write(mensajeRPM.getBytes());
                break;
        }//fin switch
    }//fin HandleMessage
};//fin handler



//TODO    HACER METODO QUE  ENVÍE EL MENSAJE DE LA VELOCIDAD

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    init();//llamas la inicializacion de todos
    if(btAdapter==null){//vamos a revisar si hay bluetooth en el dispositivo en caso de que sea null avisamos que no hay bluetooth
        Toast.makeText(getApplicationContext(), "No se detecto bluetooth", Toast.LENGTH_SHORT).show();
        finish();
    }//fin if
    else{//en caso de que si hay bluetooth vamos a continuar revisando que este o no activado
        if(!btAdapter.isEnabled()){//en caso de que no este activado
           encenderBt();//llamamos metodo enceder bluetooth
        }

        getDispositivosSincronizados(); //Vamos a revisar los dispositivos sincronizados , los vamos a meter en un array
        iniciarDescubrimiento(); //y despues vamos a iniciar el descubrimiento y vamos a poblar esa lista
    }//fin else


    // Informamos el nombre del texto view donde despliego la brujula
    brujula = (TextView) findViewById(R.id.brujula_textview);
    //Text View de la velocidad
    velocidad = (TextView) findViewById(R.id.velocidad_textview);
    // initialize your android device sensor capabilities
    mSensorManager = (SensorManager) getSystemService(SENSOR_SERVICE);

    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);


    FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
    fab.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                    .setAction("Action", null).show();
        }
    });


}




private void iniciarDescubrimiento() {
    btAdapter.cancelDiscovery();
    btAdapter.startDiscovery();
}

private void encenderBt() {//enciende el bt del dispositivo
    Intent intent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);//Haremos una peticion para activarlo
    startActivityForResult(intent, 1);
}

private void getDispositivosSincronizados() {

    ArregloDispositivos = btAdapter.getBondedDevices();
    if(ArregloDispositivos.size()>0){//si tenemos mas de un dispositivop apareado en el telefono
        for(BluetoothDevice device:ArregloDispositivos){//Para cada uno de los dispositivos apareados los vamos a incluir en nuestra lista
            dispositivosApareados.add(device.getName());

        }//fin for
    }//fin if
}

private void init() {//usado para bt , no interfiere con brjula  Aqui inicializamos

    listView=(ListView)findViewById(R.id.listView);
    listView.setOnItemClickListener(this);
    listAdapter= new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1,0 );
    listView.setAdapter(listAdapter);
    btAdapter = BluetoothAdapter.getDefaultAdapter(); //inicias un adaptador bluetooth
    dispositivosApareados = new ArrayList<String>();
    filtro = new IntentFilter(BluetoothDevice.ACTION_FOUND);
    dispositivos = new ArrayList<BluetoothDevice>();
    receptor = new BroadcastReceiver() { //hacemos broadcast para encontrar nuevos dispositivos
        @Override
        public void onReceive(Context context, Intent intent) {
            String Accion = intent.getAction();//realizamos una accion

            if(BluetoothDevice.ACTION_FOUND.equals(Accion)){//Si encontramos un dispositivo Bluetooth entonces lo añadimos a la lista
                BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
                dispositivos.add(device);
               // listAdapter.add(device.getName()+"\n"+device.getAddress()); ----------------------------------------------------------------------------------probable eliminacion

                String s = "";
                for(int a=0 ; a< dispositivosApareados.size(); a++){
                    if(device.getName().equals(dispositivosApareados.get(a))){//si algun elemento de los dispositivos apareados del celular y de la lista de dispositivos son iguales, sabremos que ya estaban apareados
                        s = "(Apareado)";  //una vez que sabemos que estan apareados ese valor se concatena con la direccion del dispositivo bluetooth en cuestion
                        break;
                    }//fin if
                }//fin for


                listAdapter.add(device.getName()+" "+s+" "+"\n"+device.getAddress()); //se toma el nombre del dispositivo, se le añade la marca de Apareado y se concatena su direccion tambien
            }//fin if

            else if(BluetoothAdapter.ACTION_DISCOVERY_STARTED.equals(Accion)){//comparar los strings del filtro con los strings de las acciones

            }//fin elseif started
            else if(BluetoothAdapter.ACTION_DISCOVERY_FINISHED.equals(Accion)){//comparar los strings del filtro con los strings de las acciones

            }//fin elseif finished
            else if(BluetoothAdapter.ACTION_STATE_CHANGED.equals(Accion)){//comparar los strings del filtro con los strings de las acciones
                if(btAdapter.getState() == btAdapter.STATE_OFF){//en caso de que haya un cambio de estado a apagado prendemos de nuevo
                    encenderBt();
                }//fin if state of
            }//fin elseif changed

        }//fin funcion onReceive
    };//fin broadcast receiver

    registerReceiver(receptor, filtro);
    filtro = new IntentFilter(BluetoothAdapter.ACTION_DISCOVERY_STARTED);
    registerReceiver(receptor, filtro);
    filtro = new IntentFilter(BluetoothAdapter.ACTION_DISCOVERY_FINISHED);
    registerReceiver(receptor, filtro);
    filtro = new IntentFilter(BluetoothAdapter.ACTION_STATE_CHANGED);
    registerReceiver(receptor, filtro);
}

@Override
protected void onPause(){// Estado de la aplicacion al ser Pausada
    super.onPause();
    unregisterReceiver(receptor);//debemos quitar el registro de los dispositivos bluetooth en caso de pausar la app
    // este si es para la brujula, si se pausa la app detenemos los sensores para guardar bateria
    mSensorManager.unregisterListener(this);
}//fin del metodo on Pause


@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    if(resultCode == RESULT_CANCELED){
        Toast.makeText(getBaseContext(), "El bluetooth debe ser activado", Toast.LENGTH_SHORT).show();
        finish();//si el usuario cancela la activacion del bluetooth terminamos el uso de la app pues no funcionaria de ese modo
    }//fin if
}

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

    // for the system's orientation sensor registered listeners
    mSensorManager.registerListener(this, mSensorManager.getDefaultSensor(Sensor.TYPE_ORIENTATION),
            SensorManager.SENSOR_DELAY_GAME);
}


@Override
public void onSensorChanged(SensorEvent event) {

    float x = event.values[0];
    String dir = "";
    if (x >= 337.5 || x < 22.5) {
        dir = "N";
    } else if (x >= 22.5 && x < 67.5) {
        dir = "NE";
    } else if (x >= 67.5 && x < 112.5) {
        dir = "E";
    } else if (x >= 112.5 && x < 157.5) {
        dir = "SE";
    } else if (x >= 157.5 && x < 202.5) {
        dir = "S";
    } else if (x >= 202.5 && x < 247.5) {
        dir = "SO";
    } else if (x >= 247.5 && x < 292.5) {
        dir = "O";
    } else if (x >= 292.5 && x < 337.5) {
        dir = "NO";
    }
    brujula.setText(dir);

}



@Override
public void onAccuracyChanged(Sensor sensor, int accuracy) {
    // not in use
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) {
        return true;
    }

    return super.onOptionsItemSelected(item);
}


@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {//METODO ocupado por la implementacion del onItemClickListener que funcionara para hacer clickeable la lista en lugar del boton

    if(btAdapter.isDiscovering()){
        btAdapter.cancelDiscovery();
    }
    if(listAdapter.getItem(position).contains("Apareado")){
        BluetoothDevice dispositivoSeleccionado = dispositivos.get(position);//position es donde fue clickeado
        ConnectThread conectar = new ConnectThread(dispositivoSeleccionado);// esa posicion representa un dispositivo bluetooth al ser clickeado hace un thread para conectarse
        conectar.start();
    }//fin if
    else{
        Toast.makeText(getApplicationContext(),"El dispositivo no esta apareado",Toast.LENGTH_SHORT).show();
    }//fin else
}//finOnItemClick


private class ConnectThread extends Thread {
    private final BluetoothSocket mmSocket;
    private final BluetoothDevice mmDevice;


    public void VelocidadContinuo(){


    }


    public ConnectThread(BluetoothDevice device) {
        // Use a temporary object that is later assigned to mmSocket,
        // because mmSocket is final
        BluetoothSocket tmp = null;
        mmDevice = device;
        Log.i(tag, "En la parte del Socket");
        // Get a BluetoothSocket to connect with the given BluetoothDevice
        try {
            // MY_UUID is the app's UUID string, also used by the server code
            tmp = device.createRfcommSocketToServiceRecord(MY_UUID);
        } catch (IOException e) {
            Log.i(tag, "Error en el Socket");}
        mmSocket = tmp;
    }

    public void run() {
        // Cancel discovery because it will slow down the connection
        btAdapter.cancelDiscovery();

        try {
            // Connect the device through the socket. This will block
            // until it succeeds or throws an exception
            mmSocket.connect();
            Log.i(tag, "Conexión realizada con el Socket");
        } catch (IOException connectException) { Log.i(tag, "Error de conexión en run de Connect Thread");
            // Si no te puedes conectar cierras el socket y sales
            try {
                mmSocket.close();
            } catch (IOException closeException) { }
            return;

        }



        // Do work to manage the connection (in a separate thread)

        mhandler.obtainMessage(CONEXION_EXITOSA,mmSocket).sendToTarget();
    }




    /** Will cancel an in-progress connection, and close the socket */
    public void cancel() {
        try {
            mmSocket.close();
        } catch (IOException e) { }
    }
}


//--------------------------------------------------------Iniciamos con el código para el SOCKET


private class ConnectedThread extends Thread {
    private final BluetoothSocket mmSocket;
    private final InputStream mmInStream;
    private final OutputStream mmOutStream;

    public ConnectedThread(BluetoothSocket socket) {
        mmSocket = socket;
        InputStream tmpIn = null;
        OutputStream tmpOut = null;

        // Get the input and output streams, using temp objects because
        // member streams are final
        try {
            tmpIn = socket.getInputStream();
            tmpOut = socket.getOutputStream();
        } catch (IOException e) { }

        mmInStream = tmpIn;
        mmOutStream = tmpOut;
    }

    public void run() {
        byte[] buffer;   // buffer store for the stream
        int bytes; // bytes returned from read()

        // Keep listening to the InputStream until an exception occurs
        while (true) {
            try {
                // Read from the InputStream
                buffer = new byte[1024];
                bytes = mmInStream.read(buffer);
                // Enviar mensajes a la actividad de la UI
                mhandler.obtainMessage(MESSAGE_READ, bytes, -1, buffer)
                //mhandler.obtainMessage(MESSAGE_READ,mmSocket).sendToTarget(); //TEMPORAL AL RECIBIR ALGO MANDAR EL MENSAJE DE PEDIR VELOCIDAD OBD2
                        .sendToTarget();

                Log.i(tag, "Bytes leidos wooho");
                Log.i(tag, String.valueOf(bytes));

            } catch (IOException e) {
                Log.e(tag, "disconnected", e);
                // Start the service over to restart listening mode
                this.start();
                break;
            }
        }
    }

    /* Call this from the main activity to send data to the remote device */
    public void write(byte[] bytes) {
        try {
            mmOutStream.write(bytes);
        } catch (IOException e) { }
    }

    /* Call this from the main activity to shutdown the connection */
    public void cancel() {
        try {
            mmSocket.close();
        } catch (IOException e) { }
    }
}//------------------------------------------------------------------------------------------------

}

The connection socket is at the end of the code , with the write method )That is working)

And the case that do something are at the begginig.

Thanks a lot for your help guys.

Answer 1

Is your code running from a thread different from the main thread? In that case you need to switch to the main thread to show your toast message or to make modifications on the UI.

Android: Toast in a thread

In that case, all you need to do is:

    activity.runOnUiThread(new Runnable() {

    @Override
    public void run() {
        Toast.makeText(getApplicationContext(), "Conexión",
                       Toast.LENGTH_SHORT).show();

    }
});