清单文件申请权限ACCESS_NETWORK_STATE

新建广播接收者继承BroadcastReceiver,重写onReceive方法

@Override

public void onReceive(Context context,Intent intent) {

ConnectivityManager connectivityManager = (ConnectivityManager)context.getSystemService(Context.CONNECTIVITY_SERVICE);

NetworkInfo networkInfo =connectivityManager.getActiveNetworkInfo();

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

        //网络连接

}else {

        //网络断开

}

}

MainActivity注册广播接收者

IntentFilter intentFilter =new IntentFilter();

intentFilter.addAction("android.net.conn.CONNECTIVITY_CHANGE");

networkChang =new NetChange();

registerReceiver(networkChang,intentFilter);

网络连接状态发生变化时会回调onReceive方法,通过判断发送网络是否连接的消息,在需要监听的位置接收网络发生变化的消息处理即可