我在Github（https://github.com/alirezaeiii/Movies）中有一个示例，其中我有一个实用程序类来检查Internet网络连接：

class NetworkUtils(context: Context) : ConnectivityManager.NetworkCallback() {

    private val networkLiveData: MutableLiveData<Boolean> = MutableLiveData()

    private val connectivityManager =
        context.getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager

    fun getNetworkLiveData(): LiveData<Boolean> {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
            connectivityManager.registerDefaultNetworkCallback(this)
        } else {
            val builder = NetworkRequest.Builder()
            connectivityManager.registerNetworkCallback(builder.build(), this)
        }

        var isConnected = false

        connectivityManager.allNetworks.forEach { network ->
            val networkCapability = connectivityManager.getNetworkCapabilities(network)

            networkCapability?.let {
                if (it.hasCapability(NetworkCapabilities.NET_CAPABILITY_INTERNET)) {
                    isConnected = true
                    return@forEach
                }
            }
        }

        networkLiveData.postValue(isConnected)

        return networkLiveData
    }

    override fun onAvailable(network: Network) {
        networkLiveData.postValue(true)
    }

    override fun onLost(network: Network) {
        networkLiveData.postValue(false)
    }

    fun unRegister() {
        connectivityManager.unregisterNetworkCallback(this)
    }
}

在我在onCreate（）和onDestroy（）中观察到的unRegisterNetworkCallback活动中：

override fun onCreate() {
        super.onCreate(savedInstanceState)
        handleNetwork()
    }

override fun onDestroy() {
    super.onDestroy()
    networkUtils.unRegister()
}

private fun handleNetwork() {
    networkUtils.getNetworkLiveData().observe(this) { isConnected: Boolean ->
        if (!isConnected) {
            ...
        } else {
            Log.d("Test", "Connected")
            ...
        }
    }
}

我第一次启动应用程序时，“已连接”标签将被调用一次，但当我旋转设备时，它将被调用两次。这是为什么？
我有另一个示例，其中我没有使用Navigation architecture component，当我旋转时它被调用一次：https://github.com/alirezaeiii/TMDb-Paging/blob/master/app/src/main/java/com/sample/android/tmdb/ui/BaseActivity.kt
使用刀柄的供应商：

@Module
@InstallIn(SingletonComponent::class)
class AppUtilsModule {
    @Singleton
    @Provides
    fun provideNetworkUtils(context: Context): NetworkUtils {
        return NetworkUtils(context)
    }
}