使用 Connectivity Manager 监听网络变化

Question

我正在尝试使用 conenctivityManager 的方法 registerDefaultNetworkCallback() 来监听网络变化 使用来自answer的以下代码

     val connectivityManager = cotnext.getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager
        connectivityManager?.let {
            it.registerDefaultNetworkCallback(object : ConnectivityManager.NetworkCallback() {
                override fun onAvailable(network: Network) {
                    //take action when network connection is gained
                }
                override fun onLost(network: Network) {
                    //take action when network connection is lost
                }
            })
        }

但是我对这个方法有几个问题：

1. 如果手机连接了wifi但wifi没有连接到互联网怎么办
2. 在方法文档中，我读到了我不明白的内容，究竟什么时候会达到限制？如果回调被调用 100 次，那么会抛出异常吗？以及如何处理？

为避免由于应用泄漏回调导致的性能问题，系统会将未完成请求的数量限制为每个应用 100 个（由其 UID 标识），并与此方法的所有变体、requestNetwork 以及 ConnectivityDiagnosticsManager.registerConnectivityDiagnosticsCallback 共享。使用此方法请求网络将计入此限制。如果超过此限制，将引发异常。为避免遇到此问题并节省资源，请确保使用 unregisterNetworkCallback(ConnectivityManager.NetworkCallback) 取消注册回调。

Answer 1

1. 手机连接wifi但是wifi没有连接怎么办 上网

答案，这个方法会返回false

1. 在方法文档中，我阅读了我没有阅读的内容 明白，到底什么时候会达到极限？如果回调是 调用 100 次然后会抛出异常？以及如何处理 这个？

我认为这意味着如果您不能注册超过 100 个回调

Answer 2

首先，添加 ConnectivityReceiver 类：

class ConnectivityReceiver : BroadcastReceiver() {
    override fun onReceive(context: Context, intent: Intent) {
        if (connectivityReceiverListener != null) {
            connectivityReceiverListener!!.onNetworkConnectionChanged(
                isConnectedOrConnecting(
                    context
                )
            )
        }
    }

    private fun isConnectedOrConnecting(context: Context): Boolean {
        val cm = context.getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager

        if (cm != null) {
            if (Build.VERSION.SDK_INT < 23) {
                val ni = cm.activeNetworkInfo
                if (ni != null) {
                    return ni.isConnected && (ni.type == ConnectivityManager.TYPE_WIFI || ni.type == ConnectivityManager.TYPE_MOBILE)
                }
            } else {
                val n = cm.activeNetwork
                if (n != null) {
                    val nc = cm.getNetworkCapabilities(n)
                    return nc!!.hasTransport(NetworkCapabilities.TRANSPORT_CELLULAR) || nc!!.hasTransport(
                        NetworkCapabilities.TRANSPORT_WIFI
                    )
                }
            }
        }
        return false
    }

    interface ConnectivityReceiverListener {
        fun onNetworkConnectionChanged(isConnected: Boolean)
    }

    companion object {
        var connectivityReceiverListener: ConnectivityReceiverListener? = null
    }

}

然后在你的 BaseActivity 或 MainActivity 添加这些行：

 abstract class BaseActivity:AppCompatActivity(), 
      ConnectivityReceiver.ConnectivityReceiverListener {

var receiver: ConnectivityReceiver? = null

override fun onResume() {
        super.onResume()
        try {
            receiver = ConnectivityReceiver()
            registerReceiver(
                receiver!!,
                IntentFilter(ConnectivityManager.CONNECTIVITY_ACTION)
            )
            connectivityReceiverListener = this
        } catch (ex: Exception) {
            //Timber.d("Base ex ${ex.localizedMessage}")
        }

    }

    override fun onPause() {
        try {
            unregisterReceiver(receiver!!)
            receiver = null

        } catch (ex: Exception) {
        }
        super.onPause()

    }

 override fun onNetworkConnectionChanged(isConnected: Boolean) {
        showMessage(isConnected)
    }


private fun showMessage(isConnected: Boolean) {
    try {
        if (!isConnected) {
           Log.d("Connection state"," disconnected")
        } else {
            Log.d("Connection state"," connected")
        }
    } catch (ex: Exception) {
       
    }
} 
}

您应该在 OnResume 方法中注册接收器并在 OnPause 方法中取消注册它