[Android] Kotlin - SMS Receiver (인증번호 받기)

※ SMS, 전화 퍼미션 관련 구글 정책 

1. AndroidManifest.xml

<uses-permission android:name="android.permission.RECEIVE_SMS"/>

2.  사용하려는 Activity에 BroadcastReceiver 구현 및 등록

import android.content.BroadcastReceiver
lateinit var receiver : BroadcastReceiver
...
 private fun initSmsReceiver() {
      receiver = object : BroadcastReceiver() {
            override fun onReceive(context: Context?, intent: Intent?) {
                if ((intent!!.action as String) == Flag.SMS_RECEIVED) {
                    val bundle = intent.extras
                    val messages = parseSmsMessage(bundle!!)

                    if (messages.isNotEmpty()) {
                        val message = messages[0]!!.messageBody.toString() // 수신한 문자 메세지의 내용 
                        val number = extractNumber(message)
                        ...
                    }
                }
            }
        }

        // 리시버 등록
        val intentFilter = IntentFilter()
        intentFilter.addAction("android.provider.Telephony.SMS_RECEIVED")
        this.registerReceiver(receiver, intentFilter)
}

3. 문자메세지 파싱

import android.telephony.SmsMessage

private fun parseSmsMessage(bundle: Bundle): Array {
        val objects = bundle.get(" pdus")="" as="" array<*="">        
        val messages = arrayOfNulls(objects.size)

        for (i in 0 until objects.size) {
                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
                        val format = bundle.getString("format")
                        messages[i] = SmsMessage.createFromPdu(objects[i] as ByteArray, format)
                } else {
                        messages[i] = SmsMessage.createFromPdu(objects[i] as ByteArray)
                }
        }

        return messages
 }

4. String에서 number만 추출하기

private fun extractNumber(str: String): String {
        var number = ""
        val pattern = Pattern.compile("\\d+")
        val matcher = pattern.matcher(str)

        while (matcher.find()) {
            number += matcher.group()
        }

        return number
}

5. onDestroy()에서 receiver 해지

override fun onDestroy() {
    if (::receiver.isInitialized) 
            this.unregisterReceiver(receiver)
     }
     super.onDestroy()
}