Feign retry example

README.md

1. Use ErrorDecoder to wrapper the exception we need to retry.
2. Implement a retryer to retry, we can setting requestTemplate to replace some paramaters.

Main.java

package com.example.feign;

import feign.Feign;
import feign.Headers;
import feign.Logger.JavaLogger;
import feign.Logger.Level;
import feign.Param;
import feign.Request.Options;
import feign.RequestLine;
import feign.Response;
import feign.RetryableException;
import feign.Retryer;
import feign.codec.ErrorDecoder;
import feign.gson.GsonDecoder;
import java.util.List;
import java.util.concurrent.TimeUnit;

public class Main {

    public static void main(String[] args) {
        var github = Feign.builder()
                .decoder(new GsonDecoder())
                .options(new Options(5, TimeUnit.SECONDS, 10, TimeUnit.SECONDS, true))
                .logger(new JavaLogger("Github.Logger").appendToFile("github.log"))
                .retryer(new MyRetryer())
                .logLevel(Level.FULL)
                .errorDecoder(new ErrorDecoder() {
                    private final ErrorDecoder defaultErrorDecoder = new Default();

                    @Override
                    public Exception decode(String methodKey, Response response) {
                        // wrapper 401 and 403 to RetryableException in order to retry
                        if (response.status() == 401 || response.status() == 403) {
                            return new RetryableException(response.status(), response.reason(), response.request().httpMethod(), null, response.request());
                        }
                        return defaultErrorDecoder.decode(methodKey, response);
                    }
                })
                .target(Github.class, "https://api.github.com");

        var contributors = github.contributors("xialeistudio", "xialeistudio.github.io", "xx");
        for (var contributor : contributors) {
            System.out.println(contributor.login + " " + contributor.contributions);
        }

    }

    static class MyRetryer implements Retryer {

        private int attempt = 1;

        @Override
        public void continueOrPropagate(RetryableException e) {
            if (++attempt > 3) {
                throw e;
            }
            e.request().requestTemplate().removeHeader("Authorization");
            e.request().requestTemplate().header("Authorization", "Bearer xx");
            try {
                Thread.sleep(100);
            } catch (InterruptedException ex) {
                throw e;
            }
        }

        @Override
        public Retryer clone() {
            return new MyRetryer();
        }
    }

    interface Github {

        @RequestLine("GET /repos/{owner}/{repo}/contributors")
        @Headers("Authorization: Bearer {token}")
        List<Contributor> contributors(@Param("owner") String owner, @Param("repo") String repo, @Param("token") String token);
    }

    static class Contributor {

        String login;
        int contributions;
    }
}