当Android Pie上的私有DNS更改时得到通知

根据源代码JavaDoc中的注释,我找到了一个有效的解决方案

ConnectivityManager cMgr = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
if (cMgr != null) {
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
        cMgr.registerNetworkCallback(new NetworkRequest.Builder().build(), new ConnectivityManager.NetworkCallback() {
            @Override
            public void onLinkPropertiesChanged(Network network, LinkProperties linkProperties) {
                super.onLinkPropertiesChanged(network, linkProperties);
                L.d(TAG, "onLinkPropertiesChanged(Network = " + network + ", LinkProperties = " + linkProperties + ")");
                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.P) {
                    L.i(TAG, "LinkProperties.isPrivateDnsActive = " + linkProperties.isPrivateDnsActive() + ", server =" + linkProperties.getPrivateDnsServerName());
             }
        }
    });
}