如何确定在恢复 Android 应用程序时互联网访问不可用

Question

我当前的 Android 应用程序需要在用户会话期间丢失互联网访问时通知用户

我使用以下回调侦听器：-

@OptIn(DelicateCoroutinesApi::class)
class ConnectivityListener @Inject constructor() : CoroutineScope by GlobalScope, ConnectivityManager.NetworkCallback() {

    private var backgroundStateJob: Job? = null
    private val internalSharedWorkState = MutableSharedFlow<BackgroundState>(replay = 1, extraBufferCapacity = 7, onBufferOverflow = BufferOverflow.DROP_OLDEST)
    private val sharedWorkScheduleState: SharedFlow<BackgroundState> = internalSharedWorkState

    override fun onBlockedStatusChanged(network: Network, blocked: Boolean) {
        Timber.e( "onBlockedStatusChanged() called with: network = $network, blocked = $blocked")
    }
    override fun onLosing(network: Network, maxMsToLive: Int) {
        Timber.e( "onLosing() called with: network = $network, maxMsToLive = $maxMsToLive")
    }
    override fun onCapabilitiesChanged(network: Network, networkCapabilities: NetworkCapabilities) {
        Timber.e( "onCapabilitiesChanged() called with: network = $network, networkCapabilities = $networkCapabilities")
    }
    override fun onLinkPropertiesChanged(network: Network, linkProperties: LinkProperties) {
        Timber.e( "onLinkPropertiesChanged() called with: network = $network, linkProperties = $linkProperties")
    }
    override fun onUnavailable() {
        Timber.e( "onUnavailable() called")
    }

    override fun onAvailable(network: Network) {
        Timber.e("onAvailable() called with: network = $network")
        backgroundStateJob?.cancel()
        backgroundStateJob = launch(Dispatchers.IO) {
            internalSharedWorkState.emit(BackgroundState.Connected())
        }
    }

    override fun onLost(network: Network) {
        Timber.e("onLost() called with: network = $network")
        backgroundStateJob?.cancel()
        backgroundStateJob = launch(Dispatchers.IO) {
            internalSharedWorkState.emit(BackgroundState.Disconnected())
        }
    }

    fun stateFlow(): SharedFlow<BackgroundState> {
        return sharedWorkScheduleState
    }
}

此侦听器在我的基本活动中使用，如下所示：-

private val networkRequest = NetworkRequest.Builder()
    .addCapability(NetworkCapabilities.NET_CAPABILITY_INTERNET)
    .addCapability(NetworkCapabilities.NET_CAPABILITY_VALIDATED)
    .addTransportType(NetworkCapabilities.TRANSPORT_CELLULAR)
    .addTransportType(NetworkCapabilities.TRANSPORT_ETHERNET)
    .addTransportType(NetworkCapabilities.TRANSPORT_WIFI)
    .build()

...

 override fun onResume() {
        Timber.e("onResume() called")
        super.onResume()
        val connectivityManager = this.getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager
        connectivityManager.registerNetworkCallback(networkRequest, connectivityListener)

    }

    override fun onPause() {
        Timber.e("onPause() called")
        super.onPause()
        val connectivityManager = this.getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager
        connectivityManager.unregisterNetworkCallback(connectivityListener)
    }

当应用程序运行时，侦听器按预期工作每当互联网访问丢失时，可靠的信息都会在前台通知用户当前的网络状态。

当我退出应用程序时，侦听器也可以正常工作，它会进入后台并随后恢复。听众成功报告我可以访问互联网。

但是，当我将应用程序置于后台、启用飞行模式然后恢复应用程序时，侦听器无法按要求工作。

它不会检测到没有互联网访问，即使它确实检测到当应用程序从后台恢复且未启用飞行模式时互联网访问何时可用。

我做错了什么？ 从后台恢复应用程序时如何检测当前网络状态？

Answer 1

来实现所需的结果

我设法通过添加第二个网络回调（如下所示）并使用 requestNetwork() 超时

override fun onResume() {
    super.onResume()
    val connectivityManager = this.getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager
    connectivityManager.registerNetworkCallback(networkRequest, connectivityListenerMonitor)
    connectivityManager.requestNetwork(networkRequest, connectivityListener, 1000)
}

override fun onPause() {
    super.onPause()
    val connectivityManager = this.getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager
    connectivityManager.unregisterNetworkCallback(connectivityListener)
    connectivityManager.unregisterNetworkCallback(connectivityListenerMonitor)
}

当我的应用程序位于后台并且启用飞行模式时，
然后将我的应用程序带到前台，我的用户会收到没有互联网连接的通知。