README.md

Bluetooth-Connection-Library

A library to manage connection between two devices using bluetooth

Add the dependencies to your gradle

Step 1. Add the JitPack repository to your root build file.

allprojects {
		repositories {
			...
			maven { url 'https://jitpack.io' }
		}
	} 

Step 2. Add the dependency to your app level gradle build file.

dependencies {
	        implementation 'com.github.thecoderpb:Bluetooth-Connection-Library:<version>'
	}

Current <version> is 1.2.3

Usage

Create an instance of the class BluetoothConnectionManager.

BluetoothConnectionManager btConnManger = new BluetoothConnectionManager(Context context,BluetoothAdapter adapter)

Class Methods

1. getAdapter()                  |              returns bluetoothAdapter
2. isEnabled()                   |              returns a boolean checking if BT is enabled or not
3. getPairedDevices()            |              returns a list of bonded BT devices List<BluetoothDevice>
4. getSocket()                   |              returns connected BluetoothSocket
5. disconnect()                  |              closes connection

The accept method

Setup a server to listen for communications

initConnectionAccept(OnBluetoothConnect listener)

The connect method

Establish communication with server

1. connect(Bluetooth device, OnBluetoothConnect listener )
2. connect(String deviceAddress, OnBluetoothConnect listener)
3. connect(byte[] byteAddress, OnBluetoothConnect listener )
4. connect(BluetoothSocket socket, OnBluetoothConnect listener )

Interface Methods

public interface OnBluetoothConnect {

    void connectedStream(BluetoothMessageService service);

    void onReceive(String message,Object object);
}

Message Service Class

Once the device obtains the socket, it opens connection through the socket and this class helps in sending data to the remote device

NOTE: Do NOT instantiate the class and directly send message using the sendMessage() method. Use the service obtained from interface call onRecieve. (Refer Sample Code Block)

Implementation

BluetoothMessageService service;
...
@Override
public void connectedStream(BluetoothMessageService service) {
        this.service = service;
		//OR
	service.sendMessage("Message"); //Sends data to target device
    }
    
@Override
public void onReceive(String message,Object object){
    if(message != null) //check for null safety 
        textview.setText(message);
    //If message is sent as a string, onReceive will have the message as String as well as object
    //If message is sent as an object, onReceive will have the message as only object and String message will be null
}

Class Methods

1. sendMessage(String message); 
2. sendMessage(Object object); //Object must be serializable,else the method silently fails

Static Calls

BluetoothConnectionManager.getDeviceStatus(); //retrieves device status as client or server

Default return value is -1

FLAGS

BluetoothConnectionManager.CLIENT // 0
BluetoothConnectionManager.SERVER // 1

All connect() and sendMessage() methods silently fails if parameters sent are incorrect/cannot be parsed.

Sample Code

public class MainActivity extends AppCompatActivity implements OnBluetoothConnect, View.OnClickListener {

    // A basic chat app
    BluetoothConnectionManager btManager;
    BluetoothMessageService service;
    

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

        btManager = new BluetoothConnectionManager(this, BluetoothAdapter.getDefaultAdapter());
	Button button = findViewById(R.id.button);
	button.setOnClickListener(this);
        if (btManager.isEnabled())
            btManager.initConnectionAccept(this);
        else Log.i(TAG, "Enable bt");
        for (BluetoothDevice device : btManager.getPairedDevices()) {
            Log.i(TAG, device.getAddress() + " " + device.getName());
            if (device.getAddress().equals("0C:E0:DC:2E:80:53")) //Enter your device address
                btManager.connect(device, this);
        }

    }

    @Override
    public void connectedStream(BluetoothMessageService service) {
        this.service = service; // get the message service
    }

    @Override
    public void onReceive(String message,Object object) {
        Log.i(TAG, "message sent from device " + message);
    }

    @Override
    public void onClick(View v) {
        if(BluetoothConnectionManager.getDeviceStatus() == BluetoothConnectionManager.CLIENT) //only client will be able to send message
        	service.sendMessage(msg);
    }
}

LICENSE

Copyright (c) 2020 thecoderpb

/*
* ----------------------------------------------------------------------------
* "THE BEER-WARE LICENSE" (Revision 42):
* thecoderpb wrote this file.  As long as you retain this notice you
* can do whatever you want with this stuff. If we meet some day, and you think
* this stuff is worth it, you can buy me a beer in return.   
* ----------------------------------------------------------------------------
*/