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

Sending Files from Android Device via Bluetooth

This article outlines the process of sending files from an Android device to another device using Bluetooth connectivity through code.

Prerequisites

• Android Studio installed
• A basic understanding of Java programming
• Two Android devices with Bluetooth capabilities

Steps

1. Enabling Bluetooth and Checking for Availability

// Get Bluetooth Adapter
BluetoothAdapter bluetoothAdapter = BluetoothAdapter.getDefaultAdapter();

// Check if Bluetooth is available
if (bluetoothAdapter == null) {
    // Device does not support Bluetooth
} else {
    // Check if Bluetooth is enabled
    if (!bluetoothAdapter.isEnabled()) {
        // Request Bluetooth enable
        Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
        startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
    }
}

2. Discovering Devices

// Start discovery
bluetoothAdapter.startDiscovery();

// Register a BroadcastReceiver to handle discovery results
registerReceiver(mReceiver, new IntentFilter(BluetoothDevice.ACTION_FOUND));

3. Creating a Bluetooth Socket

// Get remote device address
String remoteDeviceAddress = "00:11:22:33:44:55"; // Replace with actual address

// Create UUID for the service
UUID MY_UUID = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB"); // Replace with a custom UUID

// Create a socket
BluetoothSocket socket = remoteDevice.createInsecureRfcommSocketToServiceRecord(MY_UUID);

// Connect to the socket
socket.connect();

4. Sending the File

// Get file to send
File fileToSend = new File("/storage/emulated/0/Download/myFile.txt"); // Replace with actual file path

// Create an OutputStream to the socket
OutputStream outputStream = socket.getOutputStream();

// Write the file contents to the stream
byte[] buffer = new byte[1024];
int bytesRead;
FileInputStream fileInputStream = new FileInputStream(fileToSend);
while ((bytesRead = fileInputStream.read(buffer)) > 0) {
    outputStream.write(buffer, 0, bytesRead);
}

5. Closing Connections

// Close the output stream
outputStream.close();

// Close the socket
socket.close();

Code Explanation

The provided code snippets illustrate the core functionality involved in sending files via Bluetooth. Here’s a breakdown:

1. Enabling Bluetooth and Checking Availability

• The code obtains the device’s Bluetooth adapter and checks if it’s supported.
• If Bluetooth is not enabled, it prompts the user to enable it.

2. Discovering Devices

• The code initiates Bluetooth discovery, searching for nearby devices.
• A BroadcastReceiver is registered to handle discovery results and obtain the device’s address.

3. Creating a Bluetooth Socket

• A unique UUID (Universally Unique Identifier) is defined for the service.
• A Bluetooth socket is created using the UUID and the remote device’s address.
• The socket is connected to establish a communication channel.

4. Sending the File

• The code retrieves the file to be sent.
• An output stream is created to send data through the socket.
• The file’s contents are read and written to the output stream.

5. Closing Connections

• The output stream and the socket are closed to release resources.

Receiving Files

The process for receiving files via Bluetooth is similar, involving creating a server socket and listening for incoming connections.

Considerations

• File size limits: Bluetooth may have file size limitations depending on the device and connection strength.
• Security: Ensure that Bluetooth connections are secured using pairing and encryption.
• Compatibility: Ensure that the sending and receiving devices are compatible with the Bluetooth version being used.

Conclusion

This article has provided a foundational guide to sending files from an Android device using Bluetooth. The code examples offer a practical starting point, and further customizations and error handling can be implemented to enhance the functionality.