NearbyShare

Application to share data offline within 2 android devices - Download APK

<!-- Download APK link here -->

Implementation

I have used NearBy Connections API to implement this project

Steps include:

• Add dependencies (build.gradle)

// For NearBy connections API
implementation 'com.google.android.gms:play-services-nearby:18.3.0'
// For location
implementation 'com.google.android.gms:play-services-location:20.0.0'

// For Kotlin-Coroutines(optional)
implementation "androidx.lifecycle:lifecycle-viewmodel-ktx:2.5.1"
implementation 'androidx.lifecycle:lifecycle-extensions:2.2.0'
implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-jdk8:1.6.1'
implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-play-services:1.6.1'

• Add permissions in manifest and handle in activity too

<!-- Required for Nearby Connections -->
<uses-permission android:name="android.permission.BLUETOOTH" />
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
<uses-permission android:name="android.permission.CHANGE_WIFI_STATE" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<!-- Only required for apps targeting Android 12 and higher -->
<uses-permission android:name="android.permission.BLUETOOTH_ADVERTISE" />
<uses-permission android:name="android.permission.BLUETOOTH_CONNECT" />
<uses-permission android:name="android.permission.BLUETOOTH_SCAN" />
<!-- Optional: only required for FILE payloads -->
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>

// Check permissions granted based on OS version
private fun genPermissionsAreGranted(): Boolean {
    val res = (ContextCompat.checkSelfPermission(this, Manifest.permission.READ_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED)
                && (ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) == PackageManager.PERMISSION_GRANTED)
                && (ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED)
    return if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.S)
        res && (ContextCompat.checkSelfPermission(this, Manifest.permission.BLUETOOTH_ADVERTISE) == PackageManager.PERMISSION_GRANTED)
                && (ContextCompat.checkSelfPermission(this, Manifest.permission.BLUETOOTH_SCAN) == PackageManager.PERMISSION_GRANTED)
                && (ContextCompat.checkSelfPermission(this, Manifest.permission.BLUETOOTH_CONNECT) == PackageManager.PERMISSION_GRANTED)
    else res
}

// Ask for permissions before performing any task
private fun askPermissions(){
    if(!genPermissionsAreGranted()) requestPermissionLauncher.launch(permissionsArray)
}

Permission launcher and permissions array

// Permissions array based on OS Version
private val permissionsArray = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.S) {
    arrayOf(
            Manifest.permission.BLUETOOTH_ADVERTISE,
            Manifest.permission.BLUETOOTH_SCAN,
            Manifest.permission.BLUETOOTH_CONNECT,
            Manifest.permission.READ_EXTERNAL_STORAGE,
            Manifest.permission.ACCESS_COARSE_LOCATION,
            Manifest.permission.ACCESS_FINE_LOCATION)
} else {
    arrayOf(
        Manifest.permission.READ_EXTERNAL_STORAGE,
        Manifest.permission.ACCESS_COARSE_LOCATION,
        Manifest.permission.ACCESS_FINE_LOCATION)
}
private val requestPermissionLauncher = registerForActivityResult(ActivityResultContracts.RequestMultiplePermissions()){}

• Handle transferring</br>

I have made two dialogs to handle transferring files, Advertising(Sender) and Discovering(Receiver)</br>

</br>Components involved in complete file transfer:

• ConnectionClient - Manages connection between devices
• ConnectionLifecycleCallback - Callback for connection between devices
• PayloadCallback - Callback for payload shared
• Payload - The file/data that is going to be shared</br>

</br>Methods involved in callbacks:

• ConnectionLifecycleCallback
  • onConnectionInitiated() - Found a connection, can accept in this method
  • onConnectionResult() - Share status of connection, whether established or got any errors
  • onDisconnected() - When connection demolished
• PayloadCallback
  • onPayloadReceived() - Received payload(file) transferred by sender. Save this payload in a variable for future use(not in case of sender)
  • onPayloadTransferUpdate() - Share updates on payload transfer. When the status becomes SUCCESS, save the payload(saved in above method) in local storage as file.

Tip

• If you want to demolished connection just after successfully file transfer, then do it only Discoverer(receiver) side because doing it on Advertiser(Sender) side will disconnect connection before receiver receives complete file.