How to check the network availability?

问题

I have to connect my app with server using either wifi (if it is available), or gprs (if wifi is not available). Here is my code to check the connection availability

public static final boolean isConnectionAvailable(Activity a)
{  

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

  State mobile = cm.getNetworkInfo(0).getState();

  State wifi = cm.getNetworkInfo(1).getState();

  if (wifi == NetworkInfo.State.CONNECTED || wifi == NetworkInfo.State.CONNECTING)
    {
        return true;
    }
  if (mobile == NetworkInfo.State.CONNECTED || mobile == NetworkInfo.State.CONNECTING)
    {
        return true;
    }

   return false;
}      

Is this a correct way? Can anyone suggest me a better way?

回答1:

The following very similar approach works, but has the added advantage of not caring what the underlying medium, since it looks as though there is support for more than just WiFi. Maybe these are also covered by mobile, but the docs aren't super clear:

// added as an instance method to an Activity
boolean isNetworkConnectionAvailable() {  
    ConnectivityManager cm = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo info = cm.getActiveNetworkInfo();     
    if (info == null) return false;
    State network = info.getState();
    return (network == NetworkInfo.State.CONNECTED || network == NetworkInfo.State.CONNECTING);
}     

回答2:

Network Availability Check :

private boolean isNetworkAvailable() {
    ConnectivityManager connectivityManager = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo activeNetworkInfo = connectivityManager.getActiveNetworkInfo();
    return activeNetworkInfo != null && activeNetworkInfo.isConnected();
}

来源：https://stackoverflow.com/questions/7404917/how-to-check-the-network-availability