---
id: android-notification-patterns
title: Android Notification — 채널 / 권한 / 스타일
category: Coding
status: draft
source_trust_level: B
verification_status: conceptual
created_at: 2026-05-09
updated_at: 2026-05-09
tags: [android, notification, fcm, vibe-coding]
tech_stack: { language: "Kotlin / Android", applicable_to: ["Android"] }
applied_in: []
aliases: [NotificationChannel, FCM, push, BigText, MessagingStyle, POST_NOTIFICATIONS]
---

# Android Notification

> Android 8+ = **NotificationChannel 필수**. Android 13+ = POST_NOTIFICATIONS 권한. **Style (BigText/Inbox/Messaging) 으로 풍부**. FCM 으로 push.

## 📖 핵심 개념
- Channel: 카테고리 (chat / promo / system). 사용자가 채널별 설정.
- Importance: HIGH (heads-up), DEFAULT, LOW, MIN.
- Style: 단순 / BigText / BigPicture / Messaging / Media.
- Action: 인라인 버튼 + 답장 입력.

## 💻 코드 패턴

### Channel 생성 (앱 시작)
```kotlin
class App : Application() {
    override fun onCreate() {
        super.onCreate()
        val nm = getSystemService<NotificationManager>()!!
        nm.createNotificationChannels(listOf(
            NotificationChannel("chat", "Chat", NotificationManager.IMPORTANCE_HIGH).apply {
                description = "New messages"
                enableVibration(true)
                setSound(soundUri, audioAttrs)
            },
            NotificationChannel("promo", "Promotions", NotificationManager.IMPORTANCE_LOW),
        ))
    }
}
```

### 권한 (13+)
```kotlin
private val launcher = registerForActivityResult(ActivityResultContracts.RequestPermission()) { granted -> }

if (Build.VERSION.SDK_INT >= 33 &&
    ContextCompat.checkSelfPermission(this, Manifest.permission.POST_NOTIFICATIONS) != PackageManager.PERMISSION_GRANTED) {
    launcher.launch(Manifest.permission.POST_NOTIFICATIONS)
}
```

```xml
<uses-permission android:name="android.permission.POST_NOTIFICATIONS" />
```

### 단순 notification
```kotlin
val pi = PendingIntent.getActivity(ctx, 0,
    Intent(ctx, MainActivity::class.java), PendingIntent.FLAG_IMMUTABLE)

val notif = NotificationCompat.Builder(ctx, "chat")
    .setSmallIcon(R.drawable.ic_chat)
    .setContentTitle("Alice")
    .setContentText("Hi there")
    .setContentIntent(pi)
    .setAutoCancel(true)
    .build()

NotificationManagerCompat.from(ctx).notify(notifId, notif)
```

### BigText (긴 본문)
```kotlin
.setStyle(NotificationCompat.BigTextStyle().bigText(longBody))
```

### MessagingStyle (chat)
```kotlin
val you = Person.Builder().setName("You").build()
val alice = Person.Builder().setName("Alice").setIcon(...).build()

val style = NotificationCompat.MessagingStyle(you)
    .setConversationTitle("Alice")
    .addMessage("Hi", System.currentTimeMillis() - 60_000, alice)
    .addMessage("Hello", System.currentTimeMillis(), you)

builder.setStyle(style)
```

### Action + RemoteInput (답장)
```kotlin
val replyKey = "key_reply"
val remoteInput = RemoteInput.Builder(replyKey).setLabel("Reply").build()
val replyPI = PendingIntent.getBroadcast(ctx, 0,
    Intent(ctx, ReplyReceiver::class.java).putExtra("convId", convId),
    PendingIntent.FLAG_UPDATE_CURRENT or PendingIntent.FLAG_MUTABLE)

val replyAction = NotificationCompat.Action.Builder(R.drawable.ic_reply, "Reply", replyPI)
    .addRemoteInput(remoteInput)
    .setSemanticAction(NotificationCompat.Action.SEMANTIC_ACTION_REPLY)
    .build()

builder.addAction(replyAction)
```

```kotlin
class ReplyReceiver : BroadcastReceiver() {
    override fun onReceive(context: Context, intent: Intent) {
        val text = RemoteInput.getResultsFromIntent(intent)?.getCharSequence("key_reply").toString()
        // send + update notification
    }
}
```

### FCM (push)
```kotlin
class MyFcmService : FirebaseMessagingService() {
    override fun onMessageReceived(msg: RemoteMessage) {
        val data = msg.data
        showNotification(data["title"] ?: "", data["body"] ?: "")
    }

    override fun onNewToken(token: String) {
        // 서버에 등록
    }
}
```

```xml
<service android:name=".MyFcmService" android:exported="false">
    <intent-filter>
        <action android:name="com.google.firebase.MESSAGING_EVENT" />
    </intent-filter>
</service>
```

### Group + summary
```kotlin
val groupKey = "messages-group"

val notif1 = NotificationCompat.Builder(ctx, "chat").setGroup(groupKey).build()
val notif2 = NotificationCompat.Builder(ctx, "chat").setGroup(groupKey).build()
val summary = NotificationCompat.Builder(ctx, "chat")
    .setGroup(groupKey).setGroupSummary(true)
    .setSmallIcon(R.drawable.ic_chat)
    .setContentTitle("3 new messages")
    .build()
```

### Heads-up (떠 있는 알림)
```kotlin
NotificationChannel(..., IMPORTANCE_HIGH) // 채널이 HIGH
.setPriority(NotificationCompat.PRIORITY_HIGH)
.setCategory(NotificationCompat.CATEGORY_MESSAGE)
.setFullScreenIntent(pi, true) // 전화 같은 거 (lock screen 도)
```

### Image / Avatar
```kotlin
.setLargeIcon(bitmap)
.setStyle(NotificationCompat.BigPictureStyle().bigPicture(bigBitmap))
```

## 🤔 의사결정 기준
| 종류 | 채널 / 스타일 |
|---|---|
| 채팅 | HIGH + MessagingStyle + reply action |
| 시스템 (sync 완료) | LOW + 단순 |
| 마케팅 / promo | LOW + dismissable |
| 진행 중 (다운로드) | LOW + progress |
| 알람 / 콜 | HIGH + fullScreenIntent |

## ❌ 안티패턴
- **Channel 안 만들고 notify**: 8+ 에서 안 보임.
- **권한 미요청 (13+)**: silently 차단.
- **모든 채널 HIGH**: 사용자 끄기. 적절히.
- **PendingIntent FLAG_IMMUTABLE 누락 (12+)**: SecurityException.
- **Group summary 누락 + 많은 알림**: 사용자 화남.
- **Image inline base64 큼**: 메모리.
- **`setOngoing(true)` 잘못 쓰면 dismiss 못 함**.
- **Channel 삭제 + 재생성**: 사용자 설정 잃음.

## 🤖 LLM 활용 힌트
- Channel + 권한 (13+) + Style + Action 4종.
- FCM + onMessageReceived → showNotification.
- Group key + summary.

## 🔗 관련 문서
- [[Android_Foreground_Service_Patterns]]
- [[iOS_Push_Notifications]]
- [[Native_Battery_Network_Profiling]]
