[Android]检查当前手机是否有网络

// Check network connection
private boolean isNetworkConnected(){
    ConnectivityManager connectivityManager 
            = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo activeNetworkInfo = connectivityManager.getActiveNetworkInfo();
    return activeNetworkInfo != null && activeNetworkInfo.isConnected();    
}