Force WebView to operate on a certain Network

So I dug a little bit more in this topic by myself and found some helpful information:

• If a connection should use a given network, you need to bind the sockets manually to that network or directly create the sockets via a socket factory.

• There is no possibility with the standard implementation of WebView to set a socket factory or to let it use given sockets.

• But it's possible to bind the complete app process to a network. This will ensure that from that moment on all newly created sockets will be bound to that network. (The original method to set a default network was deprecated at level 23, just have a look at the method bindProcessToNetwork() in my code below.)

• Multiple network connections are only possible for Android devices running API level 21 and higher.

• The NetworkCallback can be used to listen for any newly connected networks which fulfil a specified NetworkRequest.

With this knowledge I was able to finally find a working solution:

ConnectionFragment.java

public class ConnectionFragment extends Fragment {

    private static final String TAG = ConnectionFragment.class.getSimpleName();

    private final NetworkCallback networkCallback = new NetworkCallback();
    private ConnectivityManager connectivityManager;

    @Override
    public void onCreate(@Nullable Bundle savedInstanceState) {
        Log.v(TAG, "onCreate");
        super.onCreate(savedInstanceState);

        connectivityManager = (ConnectivityManager) getActivity().getApplicationContext().getSystemService(Context.CONNECTIVITY_SERVICE);
    }

    @Override
    public void onStart() {
        Log.v(TAG, "onStart");
        super.onStart();

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
            registerNetworkCallback();
        }
    }

    @Override
    public void onStop() {
        Log.v(TAG, "onStop");
        super.onStop();

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
            unregisterNetworkCallback();
        }
    }

    @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
    private void registerNetworkCallback() {
        Log.v(TAG, "registerNetworkCallback");

        final NetworkRequest networkRequest = new NetworkRequest.Builder()
                .addTransportType(NetworkCapabilities.TRANSPORT_WIFI)
                .build();

        connectivityManager.registerNetworkCallback(networkRequest, networkCallback);
    }

    @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
    private void unregisterNetworkCallback() {
        Log.v(TAG, "unregisterNetworkCallback");
        connectivityManager.unregisterNetworkCallback(networkCallback);
    }

    @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
    private class NetworkCallback extends ConnectivityManager.NetworkCallback {

        @Override
        public void onAvailable(Network network) {
            Log.v(TAG, "onAvailable");
            bindProcessToNetwork(network);
        }

        @Override
        public void onLost(Network network) {
            Log.v(TAG, "onLost");
            bindProcessToNetwork(null);
        }

        private void bindProcessToNetwork(final Network network) {
            Log.v(TAG, "bindProcessToNetwork: " + network);

            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
                connectivityManager.bindProcessToNetwork(network);
            } else {
                ConnectivityManager.setProcessDefaultNetwork(network);
            }
        }

    }

}

I hope this will help someone.

But keep in mind: for all other connection relying on another network you need to configure the sockets manually.

Best regards,
winklerrr