WifiInfo 返回 null

Question

在遵循此 在线指南。我正在使用目标 API 30（在使用 Android 11 的设备上构建）。尝试使用 networkCapability 获取 Wifi SSID 会一直返回 null，而折旧的 wifiManager.connectionInfo.ssid 返回正确的 SSID。有什么想法我做错了吗？我知道 API 31 需要对此进行更改以包含 FLAG_INCLUDE_LOCATION_INFO，但我相信这应该适用于 API 30。有什么想法吗？

import android.content.Context
import android.net.ConnectivityManager
import android.net.Network
import android.net.NetworkCapabilities
import android.net.NetworkRequest
import android.net.wifi.WifiInfo
import android.net.wifi.WifiManager
import android.util.Log
import androidx.lifecycle.LiveData

private const val TAG = "NetworkStatus"

enum class NetworkStatus {
    UNAVAILABLE,
    CONNECTED_TO_XXXX,
    CONNECTED_TO_OTHER,
    CONNECTION_LOST
}

 class NetworkStatusHelper(private val context: Context) : LiveData<Pair<NetworkStatus, String>>() {

private lateinit var connectivityManagerCallback: ConnectivityManager.NetworkCallback
var connectivityManager: ConnectivityManager =
    context.getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager

val wifiManager =
    context.getSystemService(Context.WIFI_SERVICE) as WifiManager

private fun getConnectivityManagerCallback() = object : ConnectivityManager.NetworkCallback() {

    override fun onUnavailable() {
        super.onUnavailable()
        announceStatus(Pair(NetworkStatus.UNAVAILABLE, ""))
    }

    override fun onAvailable(network: Network) {
        super.onAvailable(network)

    }

    override fun onCapabilitiesChanged(
        network: Network,
        networkCapabilities: NetworkCapabilities
    ) {
        super.onCapabilitiesChanged(network, networkCapabilities)

        Log.d(TAG, "onCapabilitiesChanged: transport info = ${connectivityManager.getNetworkCapabilities(connectivityManager.activeNetwork)?.transportInfo}")
        try {
            val wifiInfo = networkCapabilities.transportInfo as WifiInfo
            
            Log.d(TAG, "onCapabilitiesChanged: wifi SSID ${wifiInfo}")

            if (wifiInfo.ssid.contains("XXXX-")) {
                announceStatus(Pair(NetworkStatus.CONNECTED_TO_XXXX, wifiInfo.ssid))
            } else {
                announceStatus(Pair(NetworkStatus.CONNECTED_TO_OTHER, wifiInfo.ssid))
            }

        }
        catch (e: Exception) {
            Log.d(TAG, "onCapabilitiesChanged: exception = $e")
        }

        try {
            Log.d(TAG, "onCapabilitiesChanged: ${wifiManager.connectionInfo.ssid}")
        } catch (e: Exception) {
            Log.d(TAG, "onAvailable: exception = $e")
        }

    }

    override fun onLost(network: Network) {
        super.onLost(network)
        announceStatus(Pair(NetworkStatus.CONNECTION_LOST, ""))
    }

}

fun announceStatus(networkResposePair: Pair<NetworkStatus, String>) {
    postValue(networkResposePair)
}

override fun onActive() {
    super.onActive()
    connectivityManagerCallback = getConnectivityManagerCallback()
    val networkRequest = NetworkRequest.Builder()
        .addTransportType(NetworkCapabilities.TRANSPORT_WIFI)
        .build()
    connectivityManager.registerNetworkCallback(networkRequest, connectivityManagerCallback)
}

override fun onInactive() {
    super.onInactive()
    connectivityManager.unregisterNetworkCallback(connectivityManagerCallback)
}
}

Gradle 中的权限：

    <uses-permission android:name="android.permission.INTERNET"/>
    <uses-permission android:name="android.permission.ACCESS_WIFI_STATE"/>
    <uses-permission android:name="android.permission.CHANGE_WIFI_STATE"/>
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>
    <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>

SDK 版本

    compileSdkVersion 31
    buildToolsVersion "30.0.3"
    minSdkVersion 30
    targetSdkVersion 31

Answer 1

创建 NetworkCallback 对象时，尝试像这样传递给构造函数 FLAG_INCLUDE_LOCATION_INFO：

object : ConnectivityManager.NetworkCallback(FLAG_INCLUDE_LOCATION_INFO) { /* your code */ }

这样我们就告诉我们想要接收一些有关网络的敏感数据，但它会起作用遗憾的是，仅适用于 API 级别 31 及更高级别。

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