Retry based on HTTP response

Question

I want to implement retry framework on HTTP response of API in java.

If response is:

400 : make the parameter null in json and retry again

202 : return success

429 : wait for 2 minutes and try again

5XX : wait for 5 minutes and try again

if retry count exceeds then throw the exception. Is there any library available which supports retry on response type and also allows to edit the request object? If no how can I design one? Is there any tutorials around it?

try this: https://github.com/Netflix/Hystrix – victor Dec 28 '17 at 17:12 — victor, Dec 28 '17 at 17:12

Mikhail Fayez · Accepted Answer · 2020-06-10T13:34:17.177

I know it's been 2 years for this question but maybe this solution helps someone. this solution works for me

public static void main(String[] args) {
        try {
            long start = System.currentTimeMillis();
            int retry = 0;
            boolean delay = false;
            int status = 0;
            do {
                if (delay) {
                    Thread.sleep(2000);
                }
                String url = "http://httpstat.us/429";
                URL u;
                u = new URL(url);
                HttpURLConnection con = (HttpURLConnection) u.openConnection();
                int random = (int) Math.random() * 10000;
                con.setRequestProperty("User-Agent", "skym/1.0.8 /" + random);
                con.setRequestProperty("Accept", "application/json");
                con.setRequestMethod("GET");
                con.setDoOutput(false);
                con.setDoInput(true);
                con.setUseCaches(false);
                con.setAllowUserInteraction(false);
                con.setConnectTimeout(30000);
                con.setReadTimeout(30000);
                con.setRequestProperty("Content-Type", "application/xml");
                status = con.getResponseCode();
                con.disconnect();
                System.out.println(status);
                System.out.println("Done in " + (System.currentTimeMillis() - start));
                retry++;
                delay = true;
            } while (retry < 5 && status == 429);

        } catch (Exception e) {
            System.out.println(e.getMessage());
            e.printStackTrace();
        }
    }

we can modify this code instead of waiting 2 minute cause some API require 5 minutes or more than five so we need to get the time we should by con.getHeaderFieldInt("Retry-After", -1);

so the code after modification will be

public static void main(String[] args) {
        try {
            long start = System.currentTimeMillis();
            int retry = 0;
            boolean delay = false;
            int MIN_RETRY_AFTER = 2;
            int MAX_RETRY_AFTER = 10;
            int status = 0;
            int retryAfter = 0;
            int random = 0;
            URL u;
            do {
                if (delay) {
                    Thread.sleep(1000 * retryAfter);
                }

                String url = "http://httpstat.us/429";

                u = new URL(url);
                HttpURLConnection con = (HttpURLConnection) u.openConnection();
                random = (int) Math.random() * 10000;
                con.setRequestProperty("User-Agent", "skym/1.0.8 /" + random);
                con.setRequestProperty("Accept", "application/json");
                con.setRequestMethod("GET");
                con.setDoOutput(false);
                con.setDoInput(true);
                con.setUseCaches(false);
                con.setAllowUserInteraction(false);
                con.setConnectTimeout(30000);
                con.setReadTimeout(30000);
                con.setRequestProperty("Content-Type", "application/xml");
                status = con.getResponseCode();
//              to get the time you should wait before the next request
                retryAfter = con.getHeaderFieldInt("Retry-After", -1);
                if (retryAfter < 0) {
                    retryAfter = 0;
                }
                if (retryAfter < MIN_RETRY_AFTER) {
                    retryAfter = MIN_RETRY_AFTER;
                } else if (retryAfter > MAX_RETRY_AFTER) {
                    retryAfter = MAX_RETRY_AFTER;
                }
                con.disconnect();
                System.out.println(status);
                System.out.println(retryAfter);
                System.out.println("Done in " + (System.currentTimeMillis() - start));
                retry++;
                delay = true;
            } while (retry < 5 && status == 429);
        } catch (Exception e) {
            System.out.println(e.getMessage());
            e.printStackTrace();
        }
    }

score 0 · Answer 2 · answered Dec 28 '17 at 17:12

Give Retrofit2 a try.

As per this answer, you can capture HTTP response codes and perform custom logic like so:

@Override
public void onResponse(Call<YourModel> call, Response<YourModel> response) {
    if (response.code() == 200) {
       // Do awesome stuff
    } else {
       // Handle other response codes
    }
}

Retry based on HTTP response

2 Answers2