Java实现第三方 HTTP 接口重试实现方式

public String callThirdPartyApi(String url) {
    int maxRetries = 3; // 最大重试次数
    int retryDelay = 2000; // 毫秒
    for (int i = 1; i <= maxRetries; i++) {
        try {
            HttpResponse<String> response = Unirest.get(url).asString();
            if (response.getStatus() == 200) {
                return response.getBody();
            }
        } catch (Exception e) {
            System.err.println("第 " + i + " 次调用失败: " + e.getMessage());
        }
        try {
            Thread.sleep(retryDelay); // 间隔
        } catch (InterruptedException ignored) {}
    }
    throw new RuntimeException("调用接口失败，已重试 " + maxRetries + " 次");
}

@Service
public class ThirdPartyApiService {

    @Retryable(
        value = {SocketTimeoutException.class, IOException.class}, // 哪些异常可重试
        maxAttempts = 3,  // 最大重试次数
        backoff = @Backoff(delay = 2000, multiplier = 2) // 2s, 4s, 8s
    )
    public String callApi(String url) {
        RestTemplate restTemplate = new RestTemplate();
        return restTemplate.getForObject(url, String.class);
    }

    // 超过最大重试次数后的兜底逻辑
    @Recover
    public String recover(Exception e, String url) {
        System.err.println("接口调用失败，进入降级逻辑: " + e.getMessage());
        return "fallback";
    }
}

@FeignClient(name = "thirdPartyApi", url = "https://api.example.com", configuration = RetryConfig.class)
public interface ThirdPartyClient {
    @GetMapping("/data")
    String getData();
}

resilience4j.retry:
  instances:
    thirdPartyRetry:
      maxAttempts: 3
      waitDuration: 2s
      enableExponentialBackoff: true
      exponentialBackoffMultiplier: 2

Retryer<String> retryer = RetryerBuilder.<String>newBuilder()
        .retryIfExceptionOfType(IOException.class) // 遇到 IOException 重试
        .retryIfResult(Objects::isNull) // 返回结果为空也重试
        .withWaitStrategy(WaitStrategies.exponentialWait(2, 10, TimeUnit.SECONDS)) // 指数退避
        .withStopStrategy(StopStrategies.stopAfterAttempt(3)) // 最多 3 次
        .build();

public String callThirdPartyApi(String url) {
    try {
        return retryer.call(() -> {
            HttpResponse<String> response = Unirest.get(url).asString();
            if (response.getStatus() != 200) {
                throw new IOException("HTTP " + response.getStatus());
            }
            return response.getBody();
        });
    } catch (Exception e) {
        throw new RuntimeException("调用失败", e);
    }
}