如何在jersey-client java中实现重试机制

Question

我正在使用jersey-client进行一些http rest api调用。现在，我想对失败的请求进行重试。假设返回的错误代码不是200，那么我想重试几次。如何使用Jersey客户端完成此操作

Answer 1

要在任何情况下实现重试，请查看Failsafe

RetryPolicy retryPolicy = new RetryPolicy()
  .retryIf((ClientResponse response) -> response.getStatus() != 200)
  .withDelay(1, TimeUnit.SECONDS)
  .withMaxRetries(3);

Failsafe.with(retryPolicy).get(() -> webResource.post(ClientResponse.class, input));

此示例在响应状态!= 200时重试，最多3次，两次重试之间的延迟为1秒。

Answer 2

晚到这里，但有几种不同的机制你可以使用。同步方法看起来像这样：

public Response execWithBackoff(Callable<Response> i) {
    ExponentialBackOff backoff = new ExponentialBackOff.Builder().build();

    long delay = 0;

    Response response;
    do {
        try {
            Thread.sleep(delay);

            response = i.call();

            if (response.getStatusInfo().getFamily() == Family.SERVER_ERROR) {
                log.warn("Server error {} when accessing path {}. Delaying {}ms", response.getStatus(), response.getLocation().toASCIIString(), delay);
            }

            delay = backoff.nextBackOffMillis();
        } catch (Exception e) { //callable throws exception
            throw new RuntimeException("Client request failed", e);
        }

    } while (delay != ExponentialBackOff.STOP && response.getStatusInfo().getFamily() == Family.SERVER_ERROR);

    if (response.getStatusInfo().getFamily() == Family.SERVER_ERROR) {
        throw new IllegalStateException("Client request failed for " + response.getLocation().toASCIIString());
    }

    return response;
}

指数回退实现基于Google客户端库：https://developers.google.com/api-client-library/java/google-http-java-client/backoff