问如何检查Android的互联网访问？InetAddress永远不会超时？

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();

    }   

}