Android check for bluetooth devices using alarm manager

README.md

Android check for bluetooth devices using alarm manager

• This uses AlaramManager to wape for every minute and checks for paired bluetooth devices.
• To make make AlarmManager to work even after rebooting we have register a BroadcastReceiver to listen reboot event, it is implemented in BootCompletedIntentReceiver

Add this dependency to build.gradle

implementation 'androidx.work:work-runtime:2.7.1'

AlarmActivity.kt

package com.test.uploadtos3

import android.os.Bundle
import androidx.appcompat.app.AppCompatActivity
import java.util.*


class AlarmActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_alarm)
        title = "KotlinApp"
        val calendar: Calendar = Calendar.getInstance()
        calendar.add(Calendar.SECOND, 30)
        val alarmUtility = AlarmUtility()
        if (alarmUtility.getPendingIntent(this) != null){
            alarmUtility.stopAlarm(this)
        }
        alarmUtility.setAlarm(this)
    }
}

AlarmReceiver.kt

package com.test.uploadtos3

import android.annotation.SuppressLint
import android.bluetooth.BluetoothDevice
import android.bluetooth.BluetoothManager
import android.content.BroadcastReceiver
import android.content.Context
import android.content.Intent
import android.os.Build
import android.util.Log
import java.lang.reflect.Method

class AlarmReceiver : BroadcastReceiver() {

    override fun onReceive(context: Context, intent: Intent) {
        // This method is called when the BroadcastReceiver is receiving an Intent broadcast.
        getDevices(context)
    }
    @SuppressLint("MissingPermission")
    private fun getDevices(context: Context){
        val btManager = context.getSystemService(Context.BLUETOOTH_SERVICE) as BluetoothManager
        val pairedDevices = btManager.adapter.bondedDevices

        if (pairedDevices.size > 0) {

            for (device in pairedDevices) {
                val deviceName = device.name
                val macAddress = device.address
                val aliasing = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.R) {
                    device.alias
                } else {
                    device.name
                }

                Log.d(
                    " pairedDevices ",
                    "paired device: $deviceName at $macAddress + $aliasing " + isConnected(device)
                )
                val preferredDevice = device // TODO change logic to get preferred device
                if(isConnected(device) && preferredDevice == device){
                    val notificationUtils = NotificationUtils(context)
                    val notification = notificationUtils.getNotificationBuilder().build()
                    notificationUtils.getManager().notify(150, notification)
                }
            }
        }
    }
    private fun isConnected(device: BluetoothDevice): Boolean {
        return try {
            val m: Method = device.javaClass.getMethod("isConnected")
            m.invoke(device) as Boolean
        } catch (e: Exception) {
            throw IllegalStateException(e)
        }
    }
}

AlarmUtility.kt

package com.test.uploadtos3

import android.app.AlarmManager
import android.app.PendingIntent
import android.content.Context
import android.content.Intent
import android.os.Build

class AlarmUtility {
    private val REMINDER_INTENT_REQUEST_CODE: Int = 1001
    fun setAlarm(context: Context) {
        val alarmManager = context.getSystemService(Context.ALARM_SERVICE) as AlarmManager
        val pendingIntent: PendingIntent? = getPendingIntent(context)
        alarmManager.setRepeating(
            AlarmManager.RTC_WAKEUP,
            System.currentTimeMillis() + (10 * 1000L),
            60*1000L,
            pendingIntent
        )
    }
    fun getPendingIntent(context: Context): PendingIntent? {
        val intent = Intent(context.applicationContext, AlarmReceiver::class.java)
        var pendingIntent: PendingIntent? = null
        pendingIntent = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.S) {
            PendingIntent.getBroadcast(context, REMINDER_INTENT_REQUEST_CODE, intent, PendingIntent.FLAG_MUTABLE)
        } else {
            PendingIntent.getBroadcast(context, REMINDER_INTENT_REQUEST_CODE, intent, PendingIntent.FLAG_UPDATE_CURRENT)
        }
        return pendingIntent
    }

    /*
     * Call stopAlarm() during logout or user disables alarms
     */
    fun stopAlarm(context: Context) {
        val alarmManager = context.getSystemService(Context.ALARM_SERVICE) as AlarmManager
        val pendingIntent: PendingIntent? = getPendingIntent(context)
        alarmManager.cancel(pendingIntent) //important
        pendingIntent?.cancel() //important
    }
}

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    package="com.test.uploadtos3">

    <uses-permission android:name="android.permission.BLUETOOTH_CONNECT" />
    <uses-permission android:name="android.permission.BLUETOOTH" />
    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
    <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED"/>

    <application
        android:allowBackup="true"
        android:dataExtractionRules="@xml/data_extraction_rules"
        android:fullBackupContent="@xml/backup_rules"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.UploadToS3"
        tools:targetApi="31">
        <activity
            android:name=".AlarmActivity"
            android:exported="true">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <receiver
            android:name=".AlarmReceiver"
            android:enabled="true"/>
        <receiver android:name=".BootCompletedIntentReceiver"
            android:enabled="true"
            android:exported="true">
            <intent-filter>
                <category android:name="android.intent.category.DEFAULT" />
                <action android:name="android.intent.action.BOOT_COMPLETED"/>
                <action android:name="android.intent.action.QUICKBOOT_POWERON"/>
                <action android:name="com.htc.intent.action.QUICKBOOT_POWERON"/>
            </intent-filter>
        </receiver>
    </application>

</manifest>

BootCompletedIntentReceiver.kt

package com.test.uploadtos3

import android.content.BroadcastReceiver
import android.content.Context
import android.content.Intent
import android.util.Log

class BootCompletedIntentReceiver : BroadcastReceiver() {
    override fun onReceive(context: Context, intent: Intent) {
        if (intent.action == "android.intent.action.BOOT_COMPLETED" || intent.action == "android.intent.action.QUICKBOOT_POWERON") {
            val alarmUtility = AlarmUtility()
            if (alarmUtility.getPendingIntent(context) != null){
                alarmUtility.stopAlarm(context)
            }
            alarmUtility.setAlarm(context)
        }
    }
}

NotificationUtils.kt

package com.test.uploadtos3

import android.annotation.TargetApi
import android.app.NotificationChannel
import android.app.NotificationManager
import android.app.PendingIntent
import android.content.Context
import android.content.ContextWrapper
import android.content.Intent
import android.graphics.Color
import android.media.RingtoneManager
import android.os.Build
import android.widget.Toast
import androidx.core.app.NotificationCompat

class NotificationUtils(base: Context) : ContextWrapper(base) {
    val MYCHANNEL_ID = "App Alert Notification ID"
    val MYCHANNEL_NAME = "App Alert Notification"

    private var manager: NotificationManager? = null

    init {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
            createChannels()
        }
        Toast.makeText(base, "Alarm triggered", Toast.LENGTH_SHORT).show()
    }

    // Create channel for Android version 26+
    @TargetApi(Build.VERSION_CODES.O)
    private fun createChannels() {
        val channel =
            NotificationChannel(MYCHANNEL_ID, MYCHANNEL_NAME, NotificationManager.IMPORTANCE_HIGH)
        channel.enableVibration(true)

        getManager().createNotificationChannel(channel)
    }

    // Get Manager
    fun getManager(): NotificationManager {
        if (manager == null) manager =
            getSystemService(NOTIFICATION_SERVICE) as NotificationManager
        return manager as NotificationManager
    }

    fun getNotificationBuilder(): NotificationCompat.Builder {
        val intent = Intent(this, AlarmActivity::class.java).apply {
            flags = Intent.FLAG_ACTIVITY_CLEAR_TASK
        }
        var pendingIntent: PendingIntent? = null
        pendingIntent = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.S) {
            PendingIntent.getActivity(this, 0, intent, PendingIntent.FLAG_MUTABLE)
        } else {
            PendingIntent.getActivity(this, 0, intent, PendingIntent.FLAG_ONE_SHOT)
        }
        return NotificationCompat.Builder(applicationContext, MYCHANNEL_ID)
            .setContentTitle("Alarm!")
            .setContentText("Your AlarmManager is working.")
            .setSmallIcon(R.drawable.ic_launcher_background)
            .setColor(Color.YELLOW)
            .setContentIntent(pendingIntent)
            .setSound(RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION))
            .setAutoCancel(true)
    }
}