用广播的方式，动态判断网络连接状态

private BroadcastReceiver myNetReceiver = new BroadcastReceiver() {



@Override

public void onReceive(Context context, Intent intent) {



String action = intent.getAction();

if (action.equals(ConnectivityManager.CONNECTIVITY_ACTION)) {



mConnectivityManager = (ConnectivityManager)getSystemService(Context.CONNECTIVITY_SERVICE);

netInfo = mConnectivityManager.getActiveNetworkInfo();

if(netInfo != null && netInfo.isAvailable()) {



/////////////网络连接

String name = netInfo.getTypeName();



if(netInfo.getType()==ConnectivityManager.TYPE_WIFI){

/////WiFi网络

}else if(netInfo.getType()==ConnectivityManager.TYPE_ETHERNET){

/////有线网络

}else if(netInfo.getType()==ConnectivityManager.TYPE_MOBILE){

/////////3g网络

}

} else {

////////网络断开

}

}



}

};

记得要注册广播***

IntentFilter mFilter = new IntentFilter();

mFilter.addAction(ConnectivityManager.CONNECTIVITY_ACTION);

registerReceiver(myNetReceiver, mFilter);