Android 中使用通知(Kotlin 版)

1. 前置条件

Android Studio：确保使用最新版本（2023.3.1+）
目标 API：最低 API 21，兼容 Android 8.0（渠道）和 13+（权限）
依赖库：使用 WorkManager 和 NotificationCompat

2. 完整实现步骤

2.1 添加权限和依赖

AndroidManifest.xml

<!-- 通知权限 -->
<uses-permission android:name="android.permission.POST_NOTIFICATIONS" /> <!-- Android 13+ 必须 -->
<uses-permission android:name="android.permission.INTERNET" /> <!-- 若需网络请求 --><application><!-- 添加你的主 Activity --><activityandroid:name=".MainActivity"android:exported="true"><intent-filter><action android:name="android.intent.action.MAIN" /><category android:name="android.intent.category.LAUNCHER" /></intent-filter></activity>
</application>

build.gradle (Module)

dependencies {// WorkManager 用于后台任务implementation "androidx.work:work-runtime-ktx:2.7.1"// 通知兼容库implementation "androidx.core:core-ktx:1.12.0"
}

2.2 创建通知渠道（Android 8.0+ 必需）

NotificationHelper.kt

import android.app.NotificationChannel
import android.app.NotificationManager
import android.content.Context
import android.os.Buildobject NotificationHelper {const val CHANNEL_ID = "dynamic_messages_channel"const val NOTIFICATION_ID = 101 // 用于更新同一通知fun createNotificationChannel(context: Context) {if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {// 避免重复创建渠道val notificationManager = context.getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManagerif (notificationManager.getNotificationChannel(CHANNEL_ID) != null) return// 配置渠道属性val name = "动态消息"val importance = NotificationManager.IMPORTANCE_HIGHval channel = NotificationChannel(CHANNEL_ID, name, importance).apply {description = "用于接收实时动态消息的推送"enableLights(true)lightColor = android.graphics.Color.RED}notificationManager.createNotificationChannel(channel)}}
}

2.3 构建动态通知

NotificationUtils.kt

import android.app.PendingIntent
import android.content.Context
import android.content.Intent
import androidx.core.app.NotificationCompat
import androidx.core.app.NotificationManagerCompat
import com.example.myapp.R // 替换为你的包名object NotificationUtils {fun showDynamicNotification(context: Context,title: String,message: String) {// 创建点击跳转逻辑（示例跳转到 MainActivity）val intent = Intent(context, MainActivity::class.java).apply {flags = Intent.FLAG_ACTIVITY_NEW_TASK or Intent.FLAG_ACTIVITY_CLEAR_TASK}val pendingIntent = PendingIntent.getActivity(context,0,intent,PendingIntent.FLAG_UPDATE_CURRENT or PendingIntent.FLAG_IMMUTABLE)// 构建通知val builder = NotificationCompat.Builder(context, NotificationHelper.CHANNEL_ID).setSmallIcon(R.drawable.ic_notification) // 必须的图标（需在 res/drawable 添加）.setContentTitle(title).setContentText(message).setPriority(NotificationCompat.PRIORITY_HIGH).setContentIntent(pendingIntent).setAutoCancel(true) // 点击后自动消失.setStyle(NotificationCompat.BigTextStyle().bigText(message)) // 长文本支持// 发送通知with(NotificationManagerCompat.from(context)) {if (NotificationManagerCompat.from(context).areNotificationsEnabled()) {notify(NotificationHelper.NOTIFICATION_ID, builder.build())}}}// 更新通知（使用相同 ID）fun updateNotification(context: Context, newTitle: String, newMessage: String) {val builder = NotificationCompat.Builder(context, NotificationHelper.CHANNEL_ID).setSmallIcon(R.drawable.ic_notification).setContentTitle(newTitle).setContentText(newMessage)NotificationManagerCompat.from(context).notify(NotificationHelper.NOTIFICATION_ID, builder.build())}
}

2.4 后台任务调度（WorkManager）

NotificationWorker.kt

import android.content.Context
import androidx.work.CoroutineWorker
import androidx.work.WorkerParameters
import kotlinx.coroutines.delayclass NotificationWorker(context: Context,params: WorkerParameters
) : CoroutineWorker(context, params) {override suspend fun doWork(): Result {// 模拟网络请求延迟delay(3000)// 获取动态数据（此处为模拟数据，实际需替换为真实逻辑）val title = "您有新的消息！"val content = "当前时间：${System.currentTimeMillis()}"// 显示通知NotificationUtils.showDynamicNotification(applicationContext, title, content)return Result.success()}
}

调度任务（在 MainActivity 中）

import android.os.Bundle
import androidx.appcompat.app.AppCompatActivity
import androidx.work.PeriodicWorkRequestBuilder
import androidx.work.WorkManager
import java.util.concurrent.TimeUnitclass MainActivity : AppCompatActivity() {override fun onCreate(savedInstanceState: Bundle?) {super.onCreate(savedInstanceState)setContentView(R.layout.activity_main)// 初始化通知渠道NotificationHelper.createNotificationChannel(this)// 请求通知权限（Android 13+）requestNotificationPermission()// 启动周期性后台任务（每15分钟一次）val workRequest = PeriodicWorkRequestBuilder<NotificationWorker>(15, TimeUnit.MINUTES // 注意：最短间隔为15分钟).build()WorkManager.getInstance(this).enqueue(workRequest)}private fun requestNotificationPermission() {if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {if (checkSelfPermission(android.Manifest.permission.POST_NOTIFICATIONS) !=PackageManager.PERMISSION_GRANTED) {requestPermissions(arrayOf(android.Manifest.permission.POST_NOTIFICATIONS),REQUEST_CODE_NOTIFICATION)}}}companion object {private const val REQUEST_CODE_NOTIFICATION = 1001}
}

2.5 处理权限请求结果

在 MainActivity 中重写 onRequestPermissionsResult：

override fun onRequestPermissionsResult(requestCode: Int,permissions: Array<String>,grantResults: IntArray
) {super.onRequestPermissionsResult(requestCode, permissions, grantResults)when (requestCode) {REQUEST_CODE_NOTIFICATION -> {if (grantResults.isNotEmpty() && grantResults[0] == PackageManager.PERMISSION_GRANTED) {// 用户已授权} else {// 处理拒绝逻辑（例如显示提示）}}}
}

3. 扩展优化建议

3.1 结合网络请求

使用 Retrofit + Kotlin Coroutines 获取真实数据：

// 在 NotificationWorker 中替换模拟数据
val response = apiService.fetchMessages()
if (response.isSuccessful) {val message = response.body()?.latestMessagemessage?.let {NotificationUtils.showDynamicNotification(context, it.title, it.content)}
}

3.2 通知分组（Android 7.0+）

val builder = NotificationCompat.Builder(...).setGroup("messages_group").setGroupSummary(true) // 分组摘要

3.3 通知操作按钮

// 添加“标记已读”操作
val readIntent = Intent(context, MarkReadReceiver::class.java)
val readPendingIntent = PendingIntent.getBroadcast(...)
builder.addAction(NotificationCompat.Action.Builder(R.drawable.ic_check,"标记已读",readPendingIntent).build()
)

4. 常见问题解决

通知不显示
- 检查是否在 Android 13+ 设备上授予了权限
- 确保通知渠道已正确创建
- 验证 setSmallIcon 使用了有效的资源 ID
后台任务不触发
- 确保 WorkManager 依赖已添加
- 检查设备是否处于 Doze 模式（测试时可暂时禁用）
通知点击无响应
- 确认 PendingIntent 的 FLAG_IMMUTABLE 正确使用
- 检查目标 Activity 是否在 Manifest 中注册