How to receive files programmatically using bluetooth

Question

I am trying to receive data (strings) from a Bluetooth enabled device whose MAC_ID is known. I have searched many examples ,but each article is pointing to Bluetooth Chat example, I think in Bluetooth Chat example, application need to be installed on both the devices for them to be connected and exchange strings.Correct me if I am wrong.
But I need to install application only on Receiver device.I have tried installing the application only on one device and tried connecting to the sender device, without success.

Answer 1

Bluetooth is a peer to peer protocol where you need to have application running on both sides. Hence if you want to exchange data very good example would be Bluetooth chat. If you want to download or transfer a file you should either implement obex or FTP profile based applications.

Answer 2

Yes you need to deploy an application on both sides. If you are really restricted in a way that you only can deploy on one side, you have to figure out which standard protocols/bluetooth profiles the other side is capable of. You can figure that out by doing a SDP lookup. For a device, you will then get a list of UUIDs identifying these services. See the bluetooth spec for well known UUIDs. As @7383 pointed out, your are most probably looking for OBEX or FTP.

If you can deploy on both sides, you can write your own app using Blaubot (disclaimer: I wrote it). A simple Blaubot program would do this:

UUID MY_UUID = UUID.fromString("33bb1246-1472-11e5-b60b-1697f925ec7b");

// onCreate() or in a service, we create a blaubot instance
// using Bluetooth to form a network and Bluetooth + NFC to find devices
IBlaubotDevice ownDevice = new BlaubotDevice();
BlaubotUUIDSet uuidSet = new BlaubotUUIDSet(MY_UUID);

BlaubotBluetoothAdapter bluetoothAdapter = new BlaubotBluetoothAdapter(uuidSet, ownDevice);
BlaubotNFCBeacon nfcBeacon = new BlaubotNFCBeacon();
BlaubotBluetoothBeacon bluetoothBeacon = new BlaubotBluetoothBeacon();
this.mBlaubot = BlaubotAndroidFactory.createBlaubot(MY_UUID, ownDevice, adapter, nfcBeacon, bluetoothBeacon);

// start and wait until connected
this.mBlaubot.startBlaubot();

// create a channel and send your file
IBlaubotChannel fileChannel = this.mBlaubot.createChannel(1);

// convert your file to its bytes
File yourFile = // ... however you get it
byte[] fileBytes = ...// ... see http://stackoverflow.com/questions/858980/file-to-byte-in-java

// send it to all connected devices
fileChannel.publish(fileBytes, true);


// to receive it on the other device, do this:
// subscribe to the channel
fileChannel.subscribe(new IBlaubotMessageListener() {
    @Override
    public void onMessage(BlaubotMessage message) {
        // extract your bytes from the message
        byte[] fileBytes = message.getPayload();
        // .. do something useful or write it to a file again
        // to write it to a file
        File file = new File(yourFilePath);
        BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(file));
        bos.write(fileBytes);
        bos.flush();
        bos.close();
    }
});

This should be all you need. To allow the devices to connect, you have to pair them before or use NFC (just hold them together, when Blaubot is started). If you go with Blaubot let me know if you have problems that can't be solved with the documentation or the android quickstart guide.

I can only guess what your actual scenario looks like. If you have two android phones, this should work. If that is not the case, you should add more informations about the involved devices. Are we really talking about (classic) Bluetooth connections or are you trying to get data from a Bluetooth Low Energy device? In this case the famous chat example will not help you either.