更新:它确实有效:TRANSPORT_CELLULAR 连接仅在 TRANSPORT_WIFI 断开时可用。除非您在手机的开发人员设置中启用了同步蜂窝数据，否则在启用 WiFi 时您将不会收到回调。

我正在尝试在手机的蜂窝数据连接发生变化时接收回叫。我基本上需要知道它何时关闭以及何时打开。

我以前使用 TelephonyManager 和 PhoneStateListener.LISTEN_SERVICE_STATE 来执行此操作，但现在我想使用 ConnectionManager 和 registerNetworkCallback 。

以下代码示例已在 Android 模拟器 (API 28)、HUAWEI P20 Lite (API 26)、HTC One M8 (API 23) 和摩托罗拉 G6 (API 26) 上进行了尝试。当我打开/关闭移动数据或激活飞行模式时，它们都不会调用任何回调。

People say this should work .

    NetworkRequest.Builder builder = new NetworkRequest.Builder();

    builder.addCapability(NetworkCapabilities.NET_CAPABILITY_INTERNET);
    builder.addTransportType(NetworkCapabilities.TRANSPORT_CELLULAR);

    connManager.registerNetworkCallback(builder.build(), new ConnectivityManager.NetworkCallback() {
        @Override
        public void onAvailable(Network network) {
            Log.d("Conman Test", "onAvailable");
        }

        @Override
        public void onLost(Network network) {
            Log.d("Conman Test", "onLost");
        }

        @Override
        public void onUnavailable() {
            Log.d("Conman Test", "onUnavailable");
        }

        @Override
        public void onCapabilitiesChanged(Network network, NetworkCapabilities networkCapabilities) {
            Log.d("Conman Test", "onCapabilitiesChanged");
        }

        @Override
        public void onLinkPropertiesChanged(Network network, LinkProperties linkProperties) {
            Log.d("Conman Test", "onLinkPropertiesChanged");
        }
    });

我已经尝试过 NetworkCapabilities.TRANSPORT_WIFI，它在所有设备上都运行良好。那么为什么不NetworkCapabilities.TRANSPORT_CELLULAR呢？

最佳答案

我没有尝试使用 NetworkCapabilities 来解决这个问题，但我使用了另一种方法来确定我的设备是通过蜂窝网络还是通过 wifi 连接的。

我刚刚注册了一个接收器

  <receiver android:name=".NetworkChangeReceiver" >
            <intent-filter>
                <action android:name="android.net.conn.CONNECTIVITY_CHANGE" />
            </intent-filter>
  </receiver>

我添加了权限

<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>

然后我做了以下

public class NetworkChangeReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
        ConnectivityManager cm =
                (ConnectivityManager)context.getSystemService(Context.CONNECTIVITY_SERVICE);

        NetworkInfo activeNetwork = cm.getActiveNetworkInfo();
        boolean isConnected = activeNetwork != null &&
                activeNetwork.isConnectedOrConnecting();

        if(activeNetwork ==null){
            Log.d("Connectivity","Not connected");
            return;
        }

        boolean isWiFi = activeNetwork.getType() == ConnectivityManager.TYPE_WIFI;

        if(isConnected  && isWiFi){
            Log.d("Connectivity","WIFI");
        }else{
            Log.d("Connectivity","CELLULAR");
        }
    }
}

对于 Oreo 设备，您可能需要在 Activity 或服务中注册接收器而不是 list

举个例子

public class MainActivity extends Activity {

    IntentFilter filter1;

    @Override
    public void onCreate() {
        filter1 = new IntentFilter("android.net.conn.CONNECTIVITY_CHANGE");
        registerReceiver(myReceiver, filter1);
    }

    //The BroadcastReceiver that listens for network change
    private final BroadcastReceiver myReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            if(intent.getAction().equalsIgnoreCase("android.net.conn.CONNECTIVITY_CHANGE")) {
                Log.d(TAG,"connectivity change");

             ConnectivityManager cm =
            (ConnectivityManager)this.getSystemService(Context.CONNECTIVITY_SERVICE);

        NetworkInfo activeNetwork = cm.getActiveNetworkInfo();
        boolean isConnected = activeNetwork != null &&
                activeNetwork.isConnectedOrConnecting();

        if(activeNetwork ==null){
            Log.d("Connectivity","Not connected");
            return;
        }

        boolean isWiFi = activeNetwork.getType() == ConnectivityManager.TYPE_WIFI;

        if(isConnected  && isWiFi){
            Log.d("Connectivity","WIFI");
        }else{
            Log.d("Connectivity","CELLULAR");
        }
            }
        }
    };

    @Override
    public void onDestroy() {
        unregisterReceiver(myReceiver);
    }
}

关于android - 使用 `TRANSPORT_CELLULAR` 时 ConnectionManager 不提供网络回调，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/52165382/