手机上网域名解析错误是怎么回事

import android.content.Context;
import android.net.ConnectivityManager;
import android.net.Network;
import android.net.NetworkCapabilities;
import android.net.NetworkRequest;
import android.os.Build;
import android.util.Log;

public class DnsChanger {
    public static void setDns(Context context, String dnsServer) {
        ConnectivityManager cm = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
        if (cm != null) {
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
                NetworkRequest.Builder builder = new NetworkRequest.Builder();
                cm.registerNetworkCallback(builder.build(), new ConnectivityManager.NetworkCallback() {
                    @Override
                    public void onAvailable(Network network) {
                        super.onAvailable(network);
                        try {
                            NetworkCapabilities nc = cm.getNetworkCapabilities(network);
                            if (nc != null && (nc.hasTransport(NetworkCapabilities.TRANSPORT_WIFI) || nc.hasTransport(NetworkCapabilities.TRANSPORT_CELLULAR))) {
                                // Set DNS server
                                Log.d("DnsChanger", "Setting DNS server to: " + dnsServer);
                                // This is a simplified example, actual implementation may vary
                            }
                        } catch (Exception e) {
                            Log.e("DnsChanger", "Error setting DNS server", e);
                        }
                    }
                });
            }
        }
    }
}