android - Android Service中如何使用MutableSharedFlow？

Question

我想在服务类中使用 MutableSharedFlow，但我不确定如何在服务结束时停止订阅。如何在服务中实现 MutableSharedFlow 功能或任何其他可用于监听流数据的功能？

Answer 1

要在 android Service 类中使用 Flow，我们需要一个 CoroutineScope 实例来处理启动协程和取消。请参阅以下代码和我的评论:

class CoroutineService : Service() {
    private val scope = CoroutineScope(Dispatchers.IO)

    private val flow = MutableSharedFlow<String>(extraBufferCapacity = 64)

    override fun onCreate() {
        super.onCreate()
        // collect data emitted by the Flow
        flow.onEach {
            // Handle data
        }.launchIn(scope)
    }

    override fun onStartCommand(@Nullable intent: Intent?, flags: Int, startId: Int): Int {
        scope.launch {
            // retrieve data from Intent and send it to Flow
            val messageFromIntent = intent?.let { it.extras?.getString("KEY_MESSAGE")} ?: ""
            flow.emit(messageFromIntent)
        }
        return START_STICKY
    }

    override fun onBind(intent: Intent?): IBinder?  = null

    override fun onDestroy() {
        scope.cancel() // cancel CoroutineScope and all launched coroutines
    }
}