CODEWITHSUNDEEP
androidarraysbluetoothsend
Arun Munirathinam
Arun Munirathinam

Reputation: 43

Sending byte array via Bluetooth(android)

I have successfully written a code to connect with a Bluetooth device and I found that I must send a byte array to control it.

01 99 02 00 99(Hex) - On 01 99 02 01 99(Hex) -off

That's a five-byte array. Is it possible to send over the Bluetooth? If so how?

So far I tried something like this, I tried for the first case (On method)

i) I converted hex to decimal and created an integer array. ii) Converted integer array into byte array iii) passed the byte array to the write function.

ON.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            int[] intarr = new int[]{1, 153, 2, 0, 153}; //hex to 
                                                        //decimal(manual)
            ByteBuffer byteBuffer= ByteBuffer.allocate(intarr.length *4);
            IntBuffer intBuffer =byteBuffer.asIntBuffer();
            intBuffer.put(intarr);
            byte[] array= byteBuffer.array();
            sendReceive.write(array);
        }
    });

ii) Write function

public void write(byte[] bytes)
    {
        try {
            outputStream.write(bytes);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

iii) entire code

package com.example.arun.bluet;

import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothServerSocket;
import android.bluetooth.BluetoothSocket;
import android.content.Intent;
import android.os.Handler;
import android.os.Message;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.TextView;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.nio.ByteBuffer;
import java.nio.IntBuffer;
import java.util.Arrays;
import java.util.Set;
import java.util.UUID;

public class MainActivity extends AppCompatActivity {

    Button listen,send, listDevices;
    ListView listView;
    TextView msg_box,status;
    EditText writeMsg;

    BluetoothAdapter bluetoothAdapter;
    BluetoothDevice[] btArray;

    SendReceive sendReceive;

    static final int STATE_LISTENING = 1;
    static final int STATE_CONNECTING=2;
    static final int STATE_CONNECTED=3;
    static final int STATE_CONNECTION_FAILED=4;
    static final int STATE_MESSAGE_RECEIVED=5;

    int REQUEST_ENABLE_BLUETOOTH=1;

    private static final String TAG = "BluetoothChatService";

    private static final String APP_NAME = "BTChat";
    private static final UUID MY_UUID=UUID.fromString("00001101-0000-1000-8000-00805F9B34FB");

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

        findViewByIdes();
        bluetoothAdapter=BluetoothAdapter.getDefaultAdapter();

        if(!bluetoothAdapter.isEnabled())
        {
            Intent enableIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
            startActivityForResult(enableIntent,REQUEST_ENABLE_BLUETOOTH);
        }

        implementListeners();
    }

    private void implementListeners() {

        listDevices.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Set<BluetoothDevice> bt=bluetoothAdapter.getBondedDevices();
                String[] strings=new String[bt.size()];
                btArray=new BluetoothDevice[bt.size()];
                int index=0;

                if( bt.size()>0)
                {
                    for(BluetoothDevice device : bt)
                    {
                        btArray[index]= device;
                        strings[index]=device.getName();
                        index++;
                    }
                    ArrayAdapter<String> arrayAdapter=new ArrayAdapter<String>(getApplicationContext(),android.R.layout.simple_list_item_1,strings);
                    listView.setAdapter(arrayAdapter);
                }
            }
        });

        listen.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                ServerClass serverClass=new ServerClass();
                serverClass.start();
            }
        });

        listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
                ClientClass clientClass=new ClientClass(btArray[i]);
                clientClass.start();

                status.setText("Connecting");
            }
        });

        send.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                int[] intarr = new int[]{1, 153, 2, 0, 153}; //hex to 
                                                        //decimal(manual)
            ByteBuffer byteBuffer= ByteBuffer.allocate(intarr.length *4);
            IntBuffer intBuffer =byteBuffer.asIntBuffer();
            intBuffer.put(intarr);
            byte[] array= byteBuffer.array();
            sendReceive.write(array);
            }
        });
    }

    Handler handler=new Handler(new Handler.Callback() {
        @Override
        public boolean handleMessage(Message msg) {

            switch (msg.what)
            {
                case STATE_LISTENING:
                    status.setText("Listening");
                    break;
                case STATE_CONNECTING:
                    status.setText("Connecting");
                    break;
                case STATE_CONNECTED:
                    status.setText("Connected");
                    break;
                case STATE_CONNECTION_FAILED:
                    status.setText("Connection Failed");
                    break;
                case STATE_MESSAGE_RECEIVED:
                    byte[] readBuff= (byte[]) msg.obj;
                    String tempMsg=new String(readBuff,0,msg.arg1);
                    msg_box.setText(tempMsg);
                    break;
            }
            return true;
        }
    });

    private void findViewByIdes() {
        listen=(Button) findViewById(R.id.listen);
        send=(Button) findViewById(R.id.send);
        listView=(ListView) findViewById(R.id.listview);
        msg_box =(TextView) findViewById(R.id.msg);
        status=(TextView) findViewById(R.id.status);
        writeMsg=(EditText) findViewById(R.id.writemsg);
        listDevices=(Button) findViewById(R.id.listDevices);
    }

    private class ServerClass extends Thread
    {
        private BluetoothServerSocket serverSocket;

        public ServerClass(){
            try {
                serverSocket=bluetoothAdapter.listenUsingRfcommWithServiceRecord(APP_NAME,MY_UUID);
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        public void run()
        {
            BluetoothSocket socket=null;

            while (socket==null)
            {
                try {
                    Message message=Message.obtain();
                    message.what=STATE_CONNECTING;
                    handler.sendMessage(message);

                    socket=serverSocket.accept();
                } catch (IOException e) {
                    e.printStackTrace();
                    Message message=Message.obtain();
                    message.what=STATE_CONNECTION_FAILED;
                    handler.sendMessage(message);
                }

                if(socket!=null)
                {
                    Message message=Message.obtain();
                    message.what=STATE_CONNECTED;
                    handler.sendMessage(message);

                    sendReceive=new SendReceive(socket);
                    sendReceive.start();

                    break;
                }
            }
        }
    }

    private class ClientClass extends Thread
    {
        private BluetoothDevice device;
        private BluetoothSocket socket;

        public ClientClass (BluetoothDevice device1)
        {
            device=device1;

            try {
                socket=device.createRfcommSocketToServiceRecord(MY_UUID);
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        public void run()
        {
            try {
                socket.connect();
                Message message=Message.obtain();
                message.what=STATE_CONNECTED;
                handler.sendMessage(message);

                sendReceive=new SendReceive(socket);
                sendReceive.start();

            } catch (IOException e) {
                e.printStackTrace();
                Log.i(TAG,"Socket failed");
                Message message=Message.obtain();
                message.what=STATE_CONNECTION_FAILED;
                handler.sendMessage(message);
            }
        }
    }

    private class SendReceive extends Thread
    {
        private final BluetoothSocket bluetoothSocket;
        private final InputStream inputStream;
        private final OutputStream outputStream;


        public SendReceive (BluetoothSocket socket)
        {
            bluetoothSocket=socket;
            InputStream tempIn=null;
            OutputStream tempOut=null;


            try {
                tempIn=bluetoothSocket.getInputStream();
                tempOut=bluetoothSocket.getOutputStream();

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

            inputStream=tempIn;
            outputStream=tempOut;
        }

        public void run()
        {
            byte[] buffer=new byte[1024];
            int bytes;

            while (true)
            {
                try {
                    bytes=inputStream.read(buffer);
                    handler.obtainMessage(STATE_MESSAGE_RECEIVED,bytes,-1,buffer).sendToTarget();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }

        public void write(byte[] bytes)
        {
            try {
                outputStream.write(bytes);
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

But the bluetooth device is not receiving the right message so far. Any help/suggestions would be appreciated.

Upvotes: 1

Views: 6329

Answers (1)

Arun Munirathinam
Arun Munirathinam

Reputation: 43

I did it by myself as I tried to write the code from scratch rather than tailoring the existing BTchat source code.

The logic is quite simple. To send the hexadecimal code i) For the ON switch

ON.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                char[] test = {0x01, 0x99, 0x02, 0x00, 0x99};
                write(test);
            }
        });

and the write function will be like

private void write(char[] ch) {

        try {

            for (int k = 0; k < ch.length; k++) {
                new DataOutputStream(socket.getOutputStream()).writeByte(ch[k]);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

ii)entire code

package com.example.arun.bt_ledrevised;

import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothSocket;
import android.content.Intent;
import android.os.ParcelUuid;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;

import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.Set;
import java.util.UUID;


public class MainActivity extends AppCompatActivity {


    Button connect, list_btn,ON,OFF;
    ListView lv; 
    BluetoothDevice[] btArray;

    int REQUEST_ENABLE_BLUETOOTH = 1;

    int A_R_E=0;

    private OutputStream os;
    private InputStream is;
    private BluetoothSocket socket;

    private static final String APP_NAME = "BTLED";
    private static final UUID MY_UUID = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB");

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


        connect = (Button) findViewById(R.id.connect);
        list_btn = (Button) findViewById(R.id.list_btn);
        ON = (Button) findViewById(R.id.on);
        OFF = (Button) findViewById(R.id.off);
        lv = (ListView) findViewById(R.id.lv);
        final BluetoothAdapter blueAdapter = BluetoothAdapter.getDefaultAdapter();

        if (blueAdapter == null) {
            finish();
        }
        if (!blueAdapter.isEnabled()) {
            Intent enableIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
            startActivityForResult(enableIntent, REQUEST_ENABLE_BLUETOOTH);
        }

        connect.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                if (!blueAdapter.isDiscovering()){
                    Intent intent =new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE);
                    startActivityForResult(intent,A_R_E);
                }
            }
        });


        list_btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Set<BluetoothDevice> bt = blueAdapter.getBondedDevices();
                String[] strings = new String[bt.size()];
                btArray = new BluetoothDevice[bt.size()];
                int index = 0;

                if (bt.size() > 0) {
                    for (BluetoothDevice device : bt) {
                        btArray[index] = device;
                        strings[index] = device.getName();
                        index++;
                    }
                    ArrayAdapter<String> arrayAdapter = new ArrayAdapter<String>(getApplicationContext(), android.R.layout.simple_list_item_1, strings);
                    lv.setAdapter(arrayAdapter);
                }
            }
        });

        lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
                BluetoothDevice device = (BluetoothDevice) btArray[i];
                //uuids = device.getUuids();
                try {
                    socket = device.createRfcommSocketToServiceRecord(MY_UUID);
                    socket.connect();
                } catch (IOException e) {
                    e.printStackTrace();
                }

            }
        });

        ON.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                char[] test = {0x01, 0x99, 0x02, 0x00, 0x99};
                write(test);
            }
        });
        OFF.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                char[] test1 = {0x01, 0x99, 0x02, 0x01, 0x99};
                write(test1);
            }
        });

    }

    private void write(char[] ch) {

        try {

            for (int k = 0; k < ch.length; k++) {
                new DataOutputStream(socket.getOutputStream()).writeByte(ch[k]);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public void run() {
        final int BUFFER_SIZE = 1024;
        byte[] buffer = new byte[BUFFER_SIZE];
        int bytes = 0;
        int b = BUFFER_SIZE;

        while (true){
            try {
                bytes = socket.getInputStream().read(buffer, bytes, BUFFER_SIZE - bytes);
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

Upvotes: 1

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