一次RestTemplate踩坑记录

本来想给RestTemplate加个重试机制，下面是代码：

@Component
@Slf4j
public class EcGoodsManagerImpl implements IEcGoodsManager {

    private RestTemplate restTemplate;
    
    @Autowired
    public EcGoodsManagerImpl(RestTemplateBuilder builder) {
        HttpClientBuilder clientBuilder = HttpClients.custom();
        clientBuilder.setRetryHandler((exception, executionCount, httpContext) -> {
            if (executionCount > 3) {
                log.info("重试次数超过3次");
                return false;
            }
            if (exception instanceof NoHttpResponseException || exception instanceof SocketException) {
                log.info("服务器无响应，重试次数：" + executionCount);
                return true;
            }
            return false;
        });
        CloseableHttpClient httpClient = clientBuilder.build();
        HttpComponentsClientHttpRequestFactory httpComponentsClientHttpRequestFactory = new HttpComponentsClientHttpRequestFactory(httpClient);
        builder.requestFactory(() -> httpComponentsClientHttpRequestFactory);
        restTemplate = builder.build();
    }
}

后来发现重试机制不生效，debug发现没有用上面定义的RetryHandler

image.png

经过排查发现，是以下代码有问题

builder.requestFactory(() -> httpComponentsClientHttpRequestFactory);
restTemplate = builder.build();

builder.requestFactory(() -> httpComponentsClientHttpRequestFactory)这个方法，查看源码，才知道会返回一个新的Builder

public RestTemplateBuilder requestFactory(Supplier<ClientHttpRequestFactory> requestFactory) {
        Assert.notNull(requestFactory, "RequestFactory Supplier must not be null");
        return new RestTemplateBuilder(this.requestFactoryCustomizer, this.detectRequestFactory, this.rootUri, this.messageConverters, this.interceptors, requestFactory, this.uriTemplateHandler, this.errorHandler, this.basicAuthentication, this.defaultHeaders, this.customizers, this.requestCustomizers);
}

上面写法调用了requestFactory方法，返回的新Builder没有接收，用的还是旧的Builder，导致没有生效，正确写法应该是

restTemplate = builder.requestFactory(() -> httpComponentsClientHttpRequestFactory).build();

改了后，发现自己定义的RetryHandler生效了

image.png