Alibaba Cloud DNS:Best practices for accessing Alibaba Cloud Public DNS SDK on Android apps that use OkHttp

mOkHttpClient =new OkHttpClient.Builder()
        .dns(new Dns() {
        @NonNull
        @Override
        public List<InetAddress> lookup(String hostname) {
            Utils.checkNotNull(hostname, "hostname can not be null");
            String ips =dnsResolver.getIPsV4ByHost(url.getHost());
            String[] ipArr = ips.split(";");
            if (0 == ipArr.length) {
                return Collections.emptyList();
            }
           List<InetAddress> inetAddressList = new ArrayList<>(ipArr.length);
           for (String ip : ipArr) {
               if ("0".equals(ip)) {
                   continue;
                }
           }
           try {
                InetAddress inetAddress =InetAddress.getByName(ip);
                inetAddressList.add(inetAddress);
            } catch (UnknownHostException ignored) {
         }
      }
      return inetAddressList;
   }
})
.build();

• Implement the API for a custom DNS resolution service

1. Create a new class in the project directory to implement the Dns API.

2. Implement the Dns API and override the lookup function with API operations to resolve domain names. For more information about the API operations, see SDK for Android developer guide.

  public class OkHttpDns implements Dns {

    private static OkHttpDns instance;
    private static Object lock = new Object();
    private DNSResolver mDNSResolver = DNSResolver.getInstance();

    private OkHttpDns() {
    }

    public static OkHttpDns getInstance() {
        if (null == instance) {
            synchronized (lock) {
                if (instance == null) {
                    instance = new OkHttpDns();
                }
            }
        }
        return instance;
    }

    @Override
    public List<InetAddress> lookup(@NonNull String hostname) throws UnknownHostException {
        // Call the API operation in Alibaba Cloud Public DNS SDK for Android to resolve a domain name.
        String ip = mDNSResolver.getIPV4ByHost(hostname);
        Log.d(TAG, "mDnsCache IP: " + ip);

        if (ip != null) {
            // If the returned ip value is not null, directly use the IP address to send network requests.
            return Arrays.asList(InetAddress.getAllByName(ip));
        }
        // If null is returned, use the system DNS service to resolve the domain name.
        return Dns.SYSTEM.lookup(hostname);
    }
}

• Create an OkHttpClient instance

public void okhttpDnsRequest(String url, final Handler mHandler) {
        OkHttpClient client = new OkHttpClient.Builder()
                .dns(OkHttpDns.getInstance())
                .build();

        Request request = new Request.Builder()
                .url(url)
                .build();

        Response response = null;
        client.newCall(request).enqueue(new Callback() {
            @Override
            public void onFailure(Call call, IOException e) {
                e.printStackTrace();
            }

            @Override
            public void onResponse(Call call, Response response) throws IOException {
                if (!response.isSuccessful()) {
                    throw new IOException("Unexpected code " + response);
                }

                DataInputStream dis = new DataInputStream(response.body().byteStream());
                int len;
                byte[] buff = new byte[4096];
                StringBuilder result = new StringBuilder();
                while ((len = dis.read(buff)) != -1) {
                    result.append(new String(buff, 0, len));
                }

                String resultInfo = result.toString();
                Log.d("OkHttpDns", "Response: " + resultInfo);
             }
        });
    }