With data exchange between a mobile (android) and another device through Bluetooth communication?

If you want a great, functional example, you can look at this my GitHub application, SerialBTControl .

The ActivityMain starts ActivityDeviceList on line 159, to list the existing Bluetooth devices / that can be paired.

This ActivityDeviceList is only meant to list the devices, and return to the ActivityMain , which was the device selected by the user. Take a look at the onCreate method, line 66, especially BroadcastReceiver , which is responsible for receiving devices from Android, and forwarding them to a ListView .

The onItemClick method, at line 175, ends the ActivityDeviceList , returning the selected device to ActivityMain , which treats this term in the activityFinished method, at line 133. In activityFinished , at line 141, you create the object responsible for the communication itself, which is an object of class BTCommunicator .

The class BTCommunicator , in turn , is responsible for forwarding messages to the other device, using a common OutputStream fault of Java, as shown by the sendMessage method, at line 246.

To receive data from the other device, you should use InputStream from another Thread , as shown in the comment on line 139, which invokes the receiveMessage method, also commented on line 261. p>

This application works well, and has been thoroughly tested. You're even in Google Play .

This app, in turn, is based on another open-source project called LEGO-MINDSTORMS-MINDdroid that can also serve as a reference, just as it served me.

I've never used it on android, though, bluetooth communication is not much different from a network socket, basically you establish a channel between the two devices and send / receive data through that channel. If you yourself will implement the two points of communication is relatively easy, however, if it is to communicate with a specific device you will need to know what protocol that device implements.

The android documentation itself seems like a good starting point, it includes some functional examples on how to identify and connect to a device.

link

I have not tested it, but it seems like a good help code: [Link]

Code:

    package com.bluetooth;

import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.Set;

import android.R.bool;
import android.app.Activity;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothClass;
import android.bluetooth.BluetoothDevice;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.os.ParcelUuid;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;
import android.widget.Toast;
import android.widget.AdapterView.OnItemClickListener;

public class BluetoothDemo extends Activity {
    /** Called when the activity is first created. */
    ListView listViewPaired;
    ListView listViewDetected;
    ArrayList<String> arrayListpaired;
    Button buttonSearch,buttonOn,buttonDesc,buttonOff;
    ArrayAdapter<String> adapter,detectedAdapter;
    static HandleSeacrh handleSeacrh;
    BluetoothDevice bdDevice;
    BluetoothClass bdClass;
    ArrayList<BluetoothDevice> arrayListPairedBluetoothDevices;
    private ButtonClicked clicked;
    ListItemClickedonPaired listItemClickedonPaired;
    BluetoothAdapter bluetoothAdapter = null;
    ArrayList<BluetoothDevice> arrayListBluetoothDevices = null;
    ListItemClicked listItemClicked;
    @Override 
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        listViewDetected = (ListView) findViewById(R.id.listViewDetected);
        listViewPaired = (ListView) findViewById(R.id.listViewPaired);
        buttonSearch = (Button) findViewById(R.id.buttonSearch);
        buttonOn = (Button) findViewById(R.id.buttonOn);
        buttonDesc = (Button) findViewById(R.id.buttonDesc);
        buttonOff = (Button) findViewById(R.id.buttonOff); 
        arrayListpaired = new ArrayList<String>();
        bluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
        clicked = new ButtonClicked();
        handleSeacrh = new HandleSeacrh();
        arrayListPairedBluetoothDevices = new ArrayList<BluetoothDevice>();
        /*
         * the above declaration is just for getting the paired bluetooth devices;
         * this helps in the removing the bond between paired devices.
         */
        listItemClickedonPaired = new ListItemClickedonPaired();
        arrayListBluetoothDevices = new ArrayList<BluetoothDevice>();
        adapter= new ArrayAdapter<String>(BluetoothDemo.this, android.R.layout.simple_list_item_1, arrayListpaired);
        detectedAdapter = new ArrayAdapter<String>(BluetoothDemo.this, android.R.layout.simple_list_item_single_choice);
        listViewDetected.setAdapter(detectedAdapter);
        listItemClicked = new ListItemClicked();
        detectedAdapter.notifyDataSetChanged();
        listViewPaired.setAdapter(adapter);
    }
    @Override
    protected void onStart() {
        // TODO Auto-generated method stub
        super.onStart();
        getPairedDevices();
        buttonOn.setOnClickListener(clicked);
        buttonSearch.setOnClickListener(clicked);
        buttonDesc.setOnClickListener(clicked);
        buttonOff.setOnClickListener(clicked);
        listViewDetected.setOnItemClickListener(listItemClicked);
        listViewPaired.setOnItemClickListener(listItemClickedonPaired);
    }
    private void getPairedDevices() {
        Set<BluetoothDevice> pairedDevice = bluetoothAdapter.getBondedDevices();            
        if(pairedDevice.size()>0)
        {
            for(BluetoothDevice device : pairedDevice)
            {
                arrayListpaired.add(device.getName()+"\n"+device.getAddress());
                arrayListPairedBluetoothDevices.add(device);
            }
        }
        adapter.notifyDataSetChanged();
    }
    class ListItemClicked implements OnItemClickListener
    {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
            // TODO Auto-generated method stub
            bdDevice = arrayListBluetoothDevices.get(position);
            //bdClass = arrayListBluetoothDevices.get(position);
            Log.i("Log", "The dvice : "+bdDevice.toString());
            /*
             * here below we can do pairing without calling the callthread(), we can directly call the
             * connect(). but for the safer side we must usethe threading object.
             */
            //callThread();
            //connect(bdDevice);
            Boolean isBonded = false;
            try {
                isBonded = createBond(bdDevice);
                if(isBonded)
                {
                    //arrayListpaired.add(bdDevice.getName()+"\n"+bdDevice.getAddress());
                    //adapter.notifyDataSetChanged();
                    getPairedDevices();
                    adapter.notifyDataSetChanged();
                }
            } catch (Exception e) {
                e.printStackTrace(); 
            }//connect(bdDevice);
            Log.i("Log", "The bond is created: "+isBonded);
        }       
    }
    class ListItemClickedonPaired implements OnItemClickListener
    {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position,long id) {
            bdDevice = arrayListPairedBluetoothDevices.get(position);
            try {
                Boolean removeBonding = removeBond(bdDevice);
                if(removeBonding)
                {
                    arrayListpaired.remove(position);
                    adapter.notifyDataSetChanged();
                }


                Log.i("Log", "Removed"+removeBonding);
            } catch (Exception e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    }
    /*private void callThread() {
        new Thread(){
            public void run() {
                Boolean isBonded = false;
                try {
                    isBonded = createBond(bdDevice);
                    if(isBonded)
                    {
                        arrayListpaired.add(bdDevice.getName()+"\n"+bdDevice.getAddress());
                        adapter.notifyDataSetChanged();
                    }
                } catch (Exception e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace(); 
                }//connect(bdDevice);
                Log.i("Log", "The bond is created: "+isBonded);
            }           
        }.start();
    }*/
    private Boolean connect(BluetoothDevice bdDevice) { 
        Boolean bool = false;
        try {
            Log.i("Log", "service method is called ");
            Class cl = Class.forName("android.bluetooth.BluetoothDevice");
            Class[] par = {};
            Method method = cl.getMethod("createBond", par);
            Object[] args = {};
            bool = (Boolean) method.invoke(bdDevice);//, args);// this invoke creates the detected devices paired.
            //Log.i("Log", "This is: "+bool.booleanValue());
            //Log.i("Log", "devicesss: "+bdDevice.getName());
        } catch (Exception e) {
            Log.i("Log", "Inside catch of serviceFromDevice Method");
            e.printStackTrace();
        }
        return bool.booleanValue();
    };


    public boolean removeBond(BluetoothDevice btDevice)  
    throws Exception  
    {  
        Class btClass = Class.forName("android.bluetooth.BluetoothDevice");
        Method removeBondMethod = btClass.getMethod("removeBond");  
        Boolean returnValue = (Boolean) removeBondMethod.invoke(btDevice);  
        return returnValue.booleanValue();  
    }


    public boolean createBond(BluetoothDevice btDevice)  
    throws Exception  
    { 
        Class class1 = Class.forName("android.bluetooth.BluetoothDevice");
        Method createBondMethod = class1.getMethod("createBond");  
        Boolean returnValue = (Boolean) createBondMethod.invoke(btDevice);  
        return returnValue.booleanValue();  
    }  


    class ButtonClicked implements OnClickListener
    {
        @Override
        public void onClick(View view) {
            switch (view.getId()) {
            case R.id.buttonOn:
                onBluetooth();
                break;
            case R.id.buttonSearch:
                arrayListBluetoothDevices.clear();
                startSearching();
                break;
            case R.id.buttonDesc:
                makeDiscoverable();
                break;
            case R.id.buttonOff:
                offBluetooth();
                break;
            default:
                break;
            }
        }
    }
    private BroadcastReceiver myReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            Message msg = Message.obtain();
            String action = intent.getAction();
            if(BluetoothDevice.ACTION_FOUND.equals(action)){
                Toast.makeText(context, "ACTION_FOUND", Toast.LENGTH_SHORT).show();

                BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
                try
                {
                    //device.getClass().getMethod("setPairingConfirmation", boolean.class).invoke(device, true);
                    //device.getClass().getMethod("cancelPairingUserInput", boolean.class).invoke(device);
                }
                catch (Exception e) {
                    Log.i("Log", "Inside the exception: ");
                    e.printStackTrace();
                }

                if(arrayListBluetoothDevices.size()<1) // this checks if the size of bluetooth device is 0,then add the
                {                                           // device to the arraylist.
                    detectedAdapter.add(device.getName()+"\n"+device.getAddress());
                    arrayListBluetoothDevices.add(device);
                    detectedAdapter.notifyDataSetChanged();
                }
                else
                {
                    boolean flag = true;    // flag to indicate that particular device is already in the arlist or not
                    for(int i = 0; i<arrayListBluetoothDevices.size();i++)
                    {
                        if(device.getAddress().equals(arrayListBluetoothDevices.get(i).getAddress()))
                        {
                            flag = false;
                        }
                    }
                    if(flag == true)
                    {
                        detectedAdapter.add(device.getName()+"\n"+device.getAddress());
                        arrayListBluetoothDevices.add(device);
                        detectedAdapter.notifyDataSetChanged();
                    }
                }
            }           
        }
    };
    private void startSearching() {
        Log.i("Log", "in the start searching method");
        IntentFilter intentFilter = new IntentFilter(BluetoothDevice.ACTION_FOUND);
        BluetoothDemo.this.registerReceiver(myReceiver, intentFilter);
        bluetoothAdapter.startDiscovery();
    }
    private void onBluetooth() {
        if(!bluetoothAdapter.isEnabled())
        {
            bluetoothAdapter.enable();
            Log.i("Log", "Bluetooth is Enabled");
        }
    }
    private void offBluetooth() {
        if(bluetoothAdapter.isEnabled())
        {
            bluetoothAdapter.disable();
        }
    }
    private void makeDiscoverable() {
        Intent discoverableIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE);
        discoverableIntent.putExtra(BluetoothAdapter.EXTRA_DISCOVERABLE_DURATION, 300);
        startActivity(discoverableIntent);
        Log.i("Log", "Discoverable ");
    }
    class HandleSeacrh extends Handler
    {
        @Override
        public void handleMessage(Message msg) {
            switch (msg.what) {
            case 111:

                break;

            default:
                break;
            }
        }
    }
}

And in main.xml mail:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <Button 
        android:id="@+id/buttonOn"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="On"/>
    <Button 
        android:id="@+id/buttonDesc"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="Make Discoverable"/>
   <Button 
       android:id="@+id/buttonSearch"
       android:layout_width="match_parent"
       android:layout_height="wrap_content"
       android:text="Search"/>
   <Button 
       android:id="@+id/buttonOff"
       android:layout_width="match_parent"
       android:layout_height="wrap_content"
       android:text="Bluetooth Off"/>

   <ListView 
       android:id="@+id/listViewPaired"
       android:layout_width="match_parent"
       android:layout_height="120dp">

   </ListView>

   <ListView 
       android:id="@+id/listViewDetected"
       android:layout_width="match_parent"
       android:layout_height="match_parent">

   </ListView>
</LinearLayout>

Add this permission in the "menifest file":

 <uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
    <uses-permission android:name="android.permission.BLUETOOTH" />

Other links that can help you:

How to connect with paired Bluetooth device programmatic in Android?

How to send file from Android device to other device through Bluetooth by code

You should use the Android Bluetooth SDK API, with the @PerryWerneck link and this BluetoothSocket documentation, I think you will be able to solve your problem.

link

Complete SDK Bluetooth API documentation:

link

If you already want a sample code to orient yourself, follow below:

link