Holding-android-bluetooth-Verbindung durch mehrere Aktivitäten

Was ich getan habe ist, Erstellt eine singleton-Klasse für BluetoothConnection.
So socketerstellung passiert, nur für eine Zeit.

Beim onCreate-Methode für jede Aktivität erstellt wird, wird es zuerst die fetch-Instanz BluetoothConnection Klasse.

Prozedur wird verwendet zum senden von Nachrichten von thread in BluetoothConnection-Klasse, um die entsprechende Aktivität von Einstellungen Handler.

Wie:

Class MyBTConnection{
  private static MyBTConnection connectionObj;

  private Handler mHandler;

  public MyBTConnection() { //constructor }

  public static MyBTConnection getInstance() {
    if(connectionObj == null) {
        connectionObj = new MyBTConnection();
    }
     return connectionObj;
    }
  }

  public void setHandler(Handler handler) {
     mHandler = handler;
  }


  ..... Code for Bluetooth Connection ....
  to send message : 
  mHandler.obtainMessage(what).sendToTarget();

}

//in first activity
class MainActivity extends Activity {
     private MyBTConnection connectionObj;

     public onCreate(....) {

         /*
          * Since this is first call for getInstance. A new object
          * of MyBTConnection will be created and a connection to
          * remote bluetooth device will be established.
          */
         connectionObj = MyBTConnection.getInstance();
         connectionObj.setHandler(mHandler);
     }

     private Handler mHandler = new Handler(){
          public void onReceive(...) {
               ///handle received messages here 
          }
     };

}

//in second activity
class SecondActivity extends Activity {

     private MyBTConnection connectionObj;

     public onCreate(....) {

         /*
          * Since this is second call for getInstance.
          * Object for MyBTConnection was already created in previous 
          * activity. So getInstance will return that previously
          * created object and in that object, connection to remote
          * bluetooth device is already established so you can                
          * continue your work here.
          */
         connectionObj = MyBTConnection.getInstance();
         connectionObj.setHandler(mHandler);
     }

     private Handler mHandler = new Handler(){
          public void onReceive(...) {
               ///handle received messages here 
          }
     };
}

Bei der Auswahl von Einem Gerät zu verbinden und wenn Sie klicken Sie auf die device-Liste, die Element für eine Verbindung anfordern, um das Gerät verwenden AsyncTask
und legen Sie die connect-Methode innerhalb der AsyncTask wie diese :-

 AsyncTask.execute(new Runnable() {
                    @Override
                    public void run() {

                        try {

                            bluetoothSocket = Globals.bluetoothDevice.createRfcommSocketToServiceRecord(Globals.DEFAULT_SPP_UUID);
                            bluetoothSocket.connect();

                            //After successful connect you can open InputStream
                       } catch (IOException e) {
                         e.printStackTrace();
                       }


**Here is the full code for the same problem that i have cracked :-**

listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
          @Override
          public void onItemClick(AdapterView<?> parent, View view, int position, long id) {

              lablelexconnected.setText("Connecting ...");
              bdDevice = arrayListBluetoothDevices.get(position);
              //bdClass = arrayListBluetoothDevices.get(position)
              //   Toast.makeText(getApplicationContext()," " + bdDevice.getAddress(),Toast.LENGTH_SHORT).show();
              Log.i("Log", "The dvice : " + bdDevice.toString());

              bdDevice = bluetoothAdapter.getRemoteDevice(bdDevice.getAddress());


              Globals.bluetoothDevice = bluetoothAdapter.getRemoteDevice(bdDevice.getAddress());
              System.out.println("Device in GPS Settings : " + bdDevice);
              //      startService(new Intent(getApplicationContext(),MyService.class));

             /* Intent i = new Intent(GpsSettings.this, MyService.class);
              startService(i);*/
              // finish();


            // connectDevice();


             AsyncTask.execute(new Runnable() {
                 @Override
                 public void run() {

                     try {

                         bluetoothSocket = Globals.bluetoothDevice.createRfcommSocketToServiceRecord(Globals.DEFAULT_SPP_UUID);
                         bluetoothSocket.connect();

                         //After successful connect you can open InputStream

                         InputStream in = null;
                         in = bluetoothSocket.getInputStream();
                         InputStreamReader isr = new InputStreamReader(in);
                         br = new BufferedReader(isr);

                         while (found == 0) {
                             String nmeaMessage = br.readLine();
                             Log.d("NMEA", nmeaMessage);
                             //parse NMEA messages
                             sentence = nmeaMessage;

                             System.out.println("Sentence : " + sentence);


                             if (sentence.startsWith("$GPRMC")) {
                                 String[] strValues = sentence.split(",");
                                 System.out.println("StrValues : " + strValues[3] + " " + strValues[5] + " " + strValues[8]);
                                 if (strValues[3].equals("") && strValues[5].equals("") && strValues[8].equals("")) {
                                     Toast.makeText(getApplicationContext(), "Location Not Found !!! ", Toast.LENGTH_SHORT).show();

                                 } else {

                                     latitude = Double.parseDouble(strValues[3]);
                                     if (strValues[4].charAt(0) == 'S') {
                                         latitude = -latitude;
                                     }
                                     longitude = Double.parseDouble(strValues[5]);
                                     if (strValues[6].charAt(0) == 'W') {
                                         longitude = -longitude;
                                     }
                                     course = Double.parseDouble(strValues[8]);

                                     //   Toast.makeText(getApplicationContext(), "latitude=" + latitude + " ; longitude=" + longitude + " ; course = " + course, Toast.LENGTH_SHORT).show();
                                     System.out.println("latitude=" + latitude + " ; longitude=" + longitude + " ; course = " + course);
                                 //   found = 1;

                                     NMEAToDecimalConverter(latitude, longitude);


                                 }
                             }


                         }


                     } catch (IOException e) {
                         e.printStackTrace();
                     }


                 }
             });


          }

      });