为什么具有能力的WifiNetworkSpecifier NET_CAPABILITY_INTERNET总是返回onUnavailable？

Question

我正试图让我的应用程序连接到一个WiFi AP，使用这样的代码为互联网提供WifiNetworkSpecifier。但它总是在NetworkCallback中调用NetworkCallback。

private val callback: ConnectivityManager.NetworkCallback = object : ConnectivityManager.NetworkCallback() {
    override fun onAvailable(network: Network) {
        super.onAvailable(network)
    }
    override fun onLost(network: Network) {
        super.onLost(network)
    }
    override fun onLosing(network: Network, maxMsToLive: Int) {
        super.onLosing(network, maxMsToLive)
    }
    override fun onUnavailable() {
        super.onUnavailable()
    }
    override fun onCapabilitiesChanged(network: Network, networkCapabilities: NetworkCapabilities) {
        super.onCapabilitiesChanged(network, networkCapabilities)
    }
    override fun onLinkPropertiesChanged(network: Network, linkProperties: LinkProperties) {
        super.onLinkPropertiesChanged(network, linkProperties)
    }
    override fun onBlockedStatusChanged(network: Network, blocked: Boolean) {
        super.onBlockedStatusChanged(network, blocked)
    }
}

val networkSpecifier: NetworkSpecifier = WifiNetworkSpecifier.Builder()
        .setSsid("SsidName")
        .setWpa2Passphrase("wifipassword")
        .build()

    val networkRequest: NetworkRequest = NetworkRequest.Builder()
        .addTransportType(NetworkCapabilities.TRANSPORT_WIFI)
        .addCapability(NetworkCapabilities.NET_CAPABILITY_INTERNET)
        .setNetworkSpecifier(networkSpecifier)
        .build()
    connectivityManager.requestNetwork(networkRequest, callback, 100000)

Answer 1

WifiNetworkSpecifier仅用于连接本地Wifi网络，例如，用于设置IoT设备，如此处所确认的：https://developer.android.com/guide/topics/connectivity/wifi-bootstrap。

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因此，如果你是.addCapability(NetworkCapabilities.NET_CAPABILITY_INTERNET)，安卓总是什么都不做，打电话给onUnavailable。

您可以在Android平台代码中看到为什么：https://cs.android.com/android/platform/superproject/+/master:packages/modules/Wifi/service/java/com/android/server/wifi/WifiNetworkFactory.java;drc=08124f52b883c61f3e17bc57dc28eca4c7f7bb72;l=487

LogCat中的消息将是E/WifiNetworkFactory: Request with wifi network specifier cannot contain NET_CAPABILITY_INTERNET. Rejecting

如果你想上网，你需要删除.addCapability(NetworkCapabilities.NET_CAPABILITY_INTERNET)线(这很有道理，哇！)并将connectivityManager.bindProcessToNetwork(network)添加到onAvailable中，如this answer中所述。注意，这是一个小黑客，将启用互联网通过Wifi为您的应用程序。