Android 判断网络是否连接

Android用来判断网络是否连接的方法：
private boolean isNetworkAvailable(){
ConnectivityManager cm (ConnectivityManager)getSystemService(CONNECTIVITY_SERVICE);
boolean isNetworkAvailable = cm.getActiveNetworkInfo() != null;
boolean isNetworkConnectd = isNetworkAvailable && cm.getActiveNetworkInfo().isConnected();
return isNetworkConnectd;
}