未联网状态会导致getActiveNetworkInfo()返回null,需要在此处加以判断
val cwjManager = mContext?.getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager
val activeNetworkInfo = cwjManager?.getActiveNetworkInfo()
if(activeNetworkInfo == null){//未联网
....
}else if(activeNetworkInfo?.isAvailable){//已联网
....
}