AlexV AlexV - 22 days ago 17
Android Question

How should I handle "No internet connection" with Retrofit on Android

I'd like to handle situations when there is no internet connection. Usually I'd run:

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

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


(from here) before sending the requests to the network and notify user if there were no internet connection.

From what I saw Retrofit does not handle this situation specifically. If there is no internet connection I'll just get
RetrofitError
with timeout as a reason.

If I'd like to incorporate this kind of check into every HTTP request with Retrofit, how should I do it? Or should I do it at all.

Thanks

Alex

Answer

What I ended up doing is creating a custom Retrofit client that checks for connectivity before executing a request and throws an exception.

public class ConnectivityAwareUrlClient implements Client {

    Logger log = LoggerFactory.getLogger(ConnectivityAwareUrlClient.class);

    public ConnectivityAwareUrlClient(Client wrappedClient, NetworkConnectivityManager ncm) {
        this.wrappedClient = wrappedClient;
        this.ncm = ncm;
    }

    Client wrappedClient;
    private NetworkConnectivityManager ncm;

    @Override
    public Response execute(Request request) throws IOException {
        if (!ncm.isConnected()) {
            log.debug("No connectivity %s ", request);
            throw new NoConnectivityException("No connectivity");
        }
        return wrappedClient.execute(request);
    }
}

and then use it when configuring RestAdapter

RestAdapter.Builder().setEndpoint(serverHost)
                     .setClient(new ConnectivityAwareUrlClient(new OkHttpClient(), ...))