How to check internet access on Android? InetAddress never timeouts...

Question

I got a AsyncTask that is supposed to check the network access to a host name. But the doInBackground is never timed out. Anyone have a clue?

public class HostAvailabilityTask extends AsyncTask<String, Void, Boolean>{

private Main main;

public HostAvailabilityTask(Main main){
    this.main = main;
}

protected Boolean doInBackground(String... params) {
    Main.Log("doInBackground() isHostAvailable():"+params[0]);

    try {
        return InetAddress.getByName(params[0]).isReachable(30); 
    } catch (UnknownHostException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
    return false;       
}

protected void onPostExecute(Boolean... result) {
    Main.Log("onPostExecute()");

    if(result[0] == false){
        main.setContentView(R.layout.splash);
        return;
    }

    main.continueAfterHostCheck();
}

}

Answer 1

Take a look at the ConnectivityManager class. You can use this class to get information on the active connections on a host. http://developer.android.com/reference/android/net/ConnectivityManager.html

EDIT: You can use

Context.getSystemService(Context.CONNECTIVITY_SERVICE).getNetworkInfo(ConnectivityManager.TYPE_MOBILE)

or

Context.getSystemService(Context.CONNECTIVITY_SERVICE).getNetworkInfo(ConnectivityManager.TYPE_WIFI)

and parse the DetailedState enum of the returned NetworkInfo object

EDIT EDIT: To find out whether you can access a host, you can use

Context.getSystemService(Context.CONNECTIVITY_SERVICE).requestRouteToHost(TYPE_WIFI, int hostAddress)

Obviously, I'm using Context.getSystemService(Context.CONNECTIVITY_SERVICE) as a proxy to say

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

Answer 2

Im using this code instead of the InetAddress :

 try {

  URL url = new URL("http://"+params[0]);

     HttpURLConnection urlc = (HttpURLConnection) url.openConnection();
     urlc.setRequestProperty("User-Agent", "Android Application:"+Z.APP_VERSION);
     urlc.setRequestProperty("Connection", "close");
     urlc.setConnectTimeout(1000 * 30); // mTimeout is in seconds
  urlc.connect();
     if (urlc.getResponseCode() == 200) {
            Main.Log("getResponseCode == 200");
      return new Boolean(true);
     }
 } catch (MalformedURLException e1) {
  // TODO Auto-generated catch block
  e1.printStackTrace();
    } catch (IOException e) {
  // TODO Auto-generated catch block
  e.printStackTrace();
 }

Answer 3

No need to be complex. The simplest and framework manner is to use ACCESS_NETWORK_STATE permission and just make a connected method

public boolean isOnline() {
 ConnectivityManager cm = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
 return cm.getActiveNetworkInfo().isConnectedOrConnecting();

}

You can also use requestROuteToHost if you have a particualr host and connection type (wifi/mobile) in mind.

Answer 4

Need also to add to the manifest the fallowing to get the getActiveNetworkInfo()

uses-permission android:name="android.permission.INTERNET"

uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"

Adrian

Answer 5

@Eddie. Just a minor edit to your solution - if the device is in airplane mode (or presumably in other situations where there's no available network), cm.getActiveNetworkInfo() will be null, so you need to add a null check. Modified solution below:

public boolean isOnline() {
    ConnectivityManager cm = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo netInfo = cm.getActiveNetworkInfo();
    if (netInfo != null && netInfo.isConnectedOrConnecting()) {
        return true;
    }
    return false;
}

One other small point, if you absolutely need a network connection at the given point in time, then it might be better to use netInfo.isConnected() rather than netInfo.isConnectedOrConnecting. I guess this is up to the indivudal use-case however.