Listening WIFI state

问题

I want to set listener to listen on wireless state,can anyone help me with my code

import android.telephony.PhoneStateListener;
import android.telephony.TelephonyManager;

...

 TelephonyManager wTelephonyManager;

...

     wTelephonyManager=(TelephonyManager)getSystemService(Context.WIFI_SERVICE);
    wTelephonyManager.listen(new PhoneL(),PhoneStateListener.LISTEN_DATA_CONNECTION_STATE);
    connManager = (ConnectivityManager) getSystemService(CONNECTIVITY_SERVICE);

//here is the event that i use that i want to listen for wifi change, and the above code is all in onCreate{}

class PhoneL extends PhoneStateListener

{   






    public void onWifiStateChanged(int state, String nesto)
    {
         mWifi = connManager.getNetworkInfo(ConnectivityManager.TYPE_WIFI);
            //mWifi.isConnectedOrConnecting()
             if(mWifi.isConnectedOrConnecting())
             {
                 Toast.makeText(WifiActivity.this,"Ima WIFI",Toast.LENGTH_LONG).show();     
             }
             else
             {
                 Toast.makeText(WifiActivity.this,"! NEMA WIFI",Toast.LENGTH_LONG).show(); 
             }


    }

}

//Can anyone please help me creating a listener that will listen to the wifi state and check if wifi is connected or connecting if is not i want to enable data packet traffic through 3g/4g

回答1:

The android system asks to switch to Data Traffic when WiFi is not connected but there is an issue.
If you turn off WiFi when screen is off, it will constantly change between WiFi and 3G network and if you have selected apps to send data in the background, it will use the data connection which is costlier if you don't have unlimited data plan.
Another issue is when you are in a area with not so strong WiFi signal, it will constantly change to Data Traffic and you will have issues with browsing or whatever.
Third issue is battery as from what I've heard it's better(battery wise) to use the WiFi connection than the data, with one Add-on don't turn off WiFi when the screen is off.(even, I do so)because turning it off and on WiFi is most costly(battery) that to be always On. so therefore leave it to the android system.

回答2:

I came across that problem too, here's how I solved it.

In my activity onCreate(..) I did

this.registerReceiver(mWifiStateChangedReceiver,new IntentFilter(WifiManager.WIFI_STATE_CHANGED_ACTION));

and additionally i created the member 'mWifiStateChangedReceiver' this way

private BroadcastReceiver mWifiStateChangedReceiver = new BroadcastReceiver()
{

    @Override
    public void onReceive(Context context, Intent intent)
    {
        // TODO Auto-generated method stub

        int extraWifiState = intent.getIntExtra(WifiManager.EXTRA_WIFI_STATE, WifiManager.WIFI_STATE_UNKNOWN);

        switch (extraWifiState)
        {
        case WifiManager.WIFI_STATE_DISABLED:
        case WifiManager.WIFI_STATE_DISABLING:
            enableUI(false);
            break;
        case WifiManager.WIFI_STATE_ENABLED:
            ConnectivityManager conMan = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE); 
            while(conMan.getActiveNetworkInfo() == null || conMan.getActiveNetworkInfo().getState() != NetworkInfo.State.CONNECTED)
            {
                try
                {
                    Thread.sleep(500);
                } catch (InterruptedException e)
                {
                    e.printStackTrace();
                }
            }
            update();
            enableUI(true);
            break;
        case WifiManager.WIFI_STATE_ENABLING:
            break;
        case WifiManager.WIFI_STATE_UNKNOWN:
            break;
        }

    }
};

As you can see, when I get WifiManager.WIFI_STATE_ENABLED I additionally test if the network is really connected, because a enabled WiFi doesn't mean it's connected. At least this was my guess, that's why I'm waiting till the network is really connected.

回答3:

If you want to listen to signal strength you can also listen at:

WifiManager.RSSI_CHANGED_ACTION

来源：https://stackoverflow.com/questions/9434235/listening-wifi-state