Android Bluetooth Client Library

This is an Android library that simplifies the process of bluetooth communication, client side.

This library does not support BLE devices;

Install

Add to your gradle dependencies:

implementation 'me.aflak.libraries:bluetooth:1.3.9'

Enable bluetooth

Careful: You also have to enable phone location in newer versions of Android.

Asking user for bluetooth activation

@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
    // ...
    // Need to ask for bluetooth permissions before calling constructor !
    // Permissions are {BLUETOOTH, BLUETOOTH_ADMIN, ACCESS_COARSE_LOCATION}
    bluetooth = new Bluetooth(this);
    bluetooth.setBluetoothCallback(bluetoothCallback);
}

@Override
protected void onStart() {
    super.onStart();
    bluetooth.onStart();
    if(bluetooth.isEnabled()){
        // doStuffWhenBluetoothOn() ...
    } else {
        bluetooth.showEnableDialog(ScanActivity.this);
    }
}

@Override
protected void onStop() {
    super.onStop();
    bluetooth.onStop();
}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    bluetooth.onActivityResult(requestCode, resultCode);
}

private BluetoothCallback bluetoothCallback = new BluetoothCallback() {
    @Override public void onBluetoothTurningOn() {}
    @Override public void onBluetoothTurningOff() {}
    @Override public void onBluetoothOff() {}

    @Override
    public void onBluetoothOn() {
        // doStuffWhenBluetoothOn() ...
    }

    @Override
    public void onUserDeniedActivation() {
        // handle activation denial...
    }
};

Without asking user for bluetooth activation

@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
    // ...
    // Need to ask for bluetooth permissions before calling constructor !
    // Permissions are {BLUETOOTH, BLUETOOTH_ADMIN, ACCESS_COARSE_LOCATION}
    bluetooth = new Bluetooth(this);
    bluetooth.setBluetoothCallback(bluetoothCallback);
}

@Override
protected void onStart() {
    super.onStart();
    bluetooth.onStart();
    if(bluetooth.isEnabled()){
        // doStuffWhenBluetoothOn() ...
    } else {
        bluetooth.enable()
    }
}

@Override
protected void onStop() {
    super.onStop();
    bluetooth.onStop();
}

private BluetoothCallback bluetoothCallback = new BluetoothCallback() {
    @Override public void onBluetoothTurningOn() {}
    @Override public void onBluetoothTurningOff() {}
    @Override public void onBluetoothOff() {}
    @Override public void onUserDeniedActivation() {}
    
    @Override
    public void onBluetoothOn() {
        // doStuffWhenBluetoothOn() ...
    }
};

Discover devices and pair

Listener

bluetooth.setDiscoveryCallback(new DiscoveryCallback() {
    @Override public void onDiscoveryStarted() {}
    @Override public void onDiscoveryFinished() {}
    @Override public void onDeviceFound(BluetoothDevice device) {}
    @Override public void onDevicePaired(BluetoothDevice device) {}
    @Override public void onDeviceUnpaired(BluetoothDevice device) {}
    @Override public void onError(String message) {}
});

Scan and Pair

bluetooth.startScanning();
bluetooth.pair(device);
bluetooth.pair(device, "optional pin");

Get paired devices

List<BluetoothDevice> devices = bluetooth.getPairedDevices();

Connect to device and communicate

Listener

bluetooth.setDeviceCallback(new DeviceCallback() {
    @Override public void onDeviceConnected(BluetoothDevice device) {}
    @Override public void onDeviceDisconnected(BluetoothDevice device, String message) {}
    @Override public void onMessage(byte[] message) {}
    @Override public void onError(String message) {}
    @Override public void onConnectError(BluetoothDevice device, String message) {}
});

Connect to device

// three options
bluetooth.connectToName("name");
bluetooth.connectToAddress("address");
bluetooth.connectToDevice(device);

Connect to device using port trick

See this post for details: https://stackoverflow.com/a/25647197/5552022

bluetooth.connectToNameWithPortTrick("name");
bluetooth.connectToAddressWithPortTrick("address");
bluetooth.connectToDeviceWithPortTrick(device);

Should be avoided

Send a message

bluetooth.send("hello, world");
bluetooth.send(new byte[]{61, 62, 63});

Receive messages

The default behavior of the library is the read from the input stream until it hits a new line, it will then propagate the message through listeners as a byte array. You can change the way the library reads from the socket by creating your own reader class. It must extend from SocketReader and you should override the byte[] read() throws IOException method. This method must block. It should not return if no values were received.

The default behavior is actually one example of implementation :

public class LineReader extends SocketReader{
    private BufferedReader reader;

    public LineReader(InputStream inputStream) {
        super(inputStream);
        reader = new BufferedReader(new InputStreamReader(inputStream));
    }

    @Override
    public byte[] read() throws IOException {
        return reader.readLine().getBytes();
    }
}

This is an implementation for a custom delimiter :

public class DelimiterReader extends SocketReader {
    private PushbackInputStream reader;
    private byte delimiter;

    public DelimiterReader(InputStream inputStream) {
        super(inputStream);
        reader = new PushbackInputStream(inputStream);
        delimiter = 0;
    }

    @Override
    public byte[] read() throws IOException {
        List<Byte> byteList = new ArrayList<>();
        byte[] tmp = new byte[1];

        while(true) {
            int n = reader.read();
            reader.unread(n);

            int count = reader.read(tmp);
            if(count > 0) {
                if(tmp[0] == delimiter){
                    byte[] returnBytes = new byte[byteList.size()];
                    for(int i=0 ; i<byteList.size() ; i++){
                        returnBytes[i] = byteList.get(i);
                    }
                    return returnBytes;
                } else {
                    byteList.add(tmp[0]);
                }
            }
        }
    }
}

Then you can use your reader :

bluetooth.setReader(LineReader.class);

JavaDoc

JavaDoc is in doc folder.

Example Code

app module

Download Demo App

License

MIT License

Copyright (c) 2017 Michel Omar Aflak

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.