如何重试Spring WebClient根据响应重试操作? [英] how to retry Spring WebClient to retry the operation based on the response?

问题描述

我一直在学习spring webflux，并被困在其中.

I've been learning spring webflux and got stuck into this one.

我已经使用WebClient从Spring应用程序请求了REST API.我想根据响应重试该请求.可以说，如果响应的属性为status: 'not-ready'，那么我需要一秒钟后重试相同的操作.

I've made a request to REST API from Spring app using WebClient. I want to retry the request based on the response. lets say if the response has property status: 'not-ready', then I need to retry the same operation after a second.

我尝试了以下方法，但不确定如何实现

I tried the following way, but not sure how to implement it

public Flux<Data> makeHttpRequest(int page) {
        Flux<Data> data = webClient.get()
                .uri("/api/users?page=" + page)
                .retrieve()
                .bodyToFlux(Data.class);
        return data;
}

GET : /api/users returns the folowing response

ex: 1 {
  status: 'ready',
  data: [......]
}

ex: 2 {
  status: 'not-ready',
  data: null
}

任何帮助将不胜感激.

Any help would be appreciated.

推荐答案

我认为实现所需的重试逻辑相当容易. 类似于以下内容:

I think it is fairly easy to implement the desired retry logic. Something along the lines of:

public class SampleRequester {

    private final ScheduledExecutorService scheduler = Executors.newScheduledThreadPool(1);

    private WebClient client;

    public SampleRequester() {
        this.client = WebClient.create();
    }

    public void scheduleRequest(int secondsDelay) {
        scheduler.schedule(this::initiateRequest, secondsDelay, SECONDS);
    }

    private void initiateRequest() {
        Mono<ResponseData> response = client.get()
                .uri("example.com")
                .retrieve()
                .bodyToMono(ResponseData.class);

        response.subscribe(this::handleResponse);
    }

    private void handleResponse(ResponseData body) {
        if("ready".equals(body.getStatus())) {
            System.out.println("No Retry");
            // Do something with the data
        } else {
            System.out.println("Retry after 1 second");
            scheduleRequest(1);
        }
    }
}

我使用以下简单模型进行响应:

I used the following simple model for the response:

public class ResponseData implements Serializable {

    private String status;

    public String getStatus() {
        return status;
    }

    public void setStatus(String status) {
        this.status = status;
    }
}   

然后，您将调用SampleRequester.scheduleRequest(0)立即发起第一个调用. 当然，您还需要进行调整，以避免硬编码请求url，扩展ResponseData，使延迟可配置和/或指数回退等.

Then you would call SampleRequester.scheduleRequest(0) to initiate the first call immediately. Of course you would also need to adapt to avoid hard-coding the request url, extending the ResponseData, make the delay configurable and/or exponential backoff etc.

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