如何在关机时等待 RestTemplate 响应？

Question

我正在使用springwithRestTemplate向POST网络服务器发送请求。

当我的应用程序关闭时（例如从 tomcat 中取消部署），关闭应该被延迟，直到收到所有挂起的响应（在超时内）。

restTemplateHttpComponentsClientHttpRequestFactory在幕后使用。

问题：我怎么知道spring延迟关机？@PreDestroy可能是一种可能性，但是如何检测 restTemplate 上的待处理请求？

Answer 1

我认为没有现成的解决方案，如https://github.com/spring-projects/spring-boot/issues/4657中所述

对于 Tomcat，下面的代码应该可以工作

@Component
@Scope("singleton")
public class ApplicationContextClosedListener implements ApplicationListener<ContextClosedEvent>, TomcatConnectorCustomizer {

    private static final Logger LOGGER = LoggerFactory.getLogger(ApplicationContextClosedListener.class);

    private volatile Connector connector;

    @Value("${timeout}")
    private Integer timeout;

    @Override
    public void customize(Connector connector) {
        this.connector = connector;
    }

    @Override
    public void onApplicationEvent(ContextClosedEvent event) {
        if (connector != null) {
            shutdownGracefully();
        }
    }

    private void shutdownGracefully() {
        connector.pause();
        Executor executor = connector.getProtocolHandler().getExecutor();

        if (executor instanceof ThreadPoolExecutor) {
            ThreadPoolExecutor threadPoolExecutor = (ThreadPoolExecutor) executor;

            try {
                threadPoolExecutor.shutdown();
                if (!threadPoolExecutor.awaitTermination(timeout, TimeUnit.SECONDS)) {
                    LOGGER.warn("Shutdown: Tomcat thread pool did not shut down gracefully within specified period. Proceeding with forceful shutdown");
                }
                threadPoolExecutor.shutdownNow();

                LOGGER.info("Shutdown: the executor shutdown completed");
            } catch (InterruptedException ex) {
                LOGGER.error("Shutdown: Interrupt signal received");
                threadPoolExecutor.shutdownNow();
                Thread.currentThread().interrupt();
            }
        }
    }
}