关于commandResult和Completable用法小笔记-优快云博客

本文链接：https://blog.youkuaiyun.com/weixin_53238530/article/details/125102895

本文探讨了如何在Java代码中正确处理支付撤销操作的CommandResult订阅问题，通过修改execute方法和publishEvent逻辑，确保事件成功发布并推送到Kafka。作者分享了解决未订阅问题的方法及优化后的代码实现。

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要在处理完成后追加一个Delete处理：

    @Nonnull
    @Override
    public Single<CommandResult> execute(@Nonnull PaymentUnallocateRequest request) {
        return validatorRegistry.getValidator(commandIdentity()).validate(request).switchIfEmpty(Single.defer(
            () -> paymentUnallocateActivityWrite(request).flatMap(
                paymentRequest -> createPaymentActivityLink(paymentRequest).flatMapSingle(
                        activityLink -> paymentUnallocateActivityApply(paymentRequest, activityLink,
                            request.getBillingViewLink()).flatMap(
                                a -> billingPaymentService.extractActivity(EntityLinkUtil.getId(activityLink), paymentRequest))
                            .flatMap(
                                activity -> paymentUnallocateActivityComplete((PaymentActivity) activity, paymentRequest)))
                    .flatMap(commandResult -> publishEventIfUnallocateDeleteMemberRecord(paymentRequest)))));
    }


    private Single<commandResult> publishEventIfUnallocateDeleteMemberRecord(BillingPaymentRequest request) {
        return Single.jues( eventPublisher.publishEventAsync(paymentEventFactory.createDeleteMemberRecordIndexEvent(request)).map(deletrMemberRecordIndexEvent -> commandResult);
    }

如上修改，发现因为没有地方订阅commandResult，publishEventAsync并没有被push，Kafka上没有发出消息。publishEventAsync return了Completable但是没有调用这个线程，我只返回了commandResult，但是commandResult并没有被订阅。

改成如下代码后，可正常push：

    public Single<CommandResult> execute(@Nonnull PaymentUnallocateRequest request) {
        return validatorRegistry.getValidator(commandIdentity()).validate(request).switchIfEmpty(Single.defer(
            () -> paymentUnallocateActivityWrite(request).flatMap(
                paymentRequest -> createPaymentActivityLink(paymentRequest).flatMapSingle(
                        activityLink -> paymentUnallocateActivityApply(paymentRequest, activityLink,
                            request.getBillingViewLink()).flatMap(
                                a -> billingPaymentService.extractActivity(EntityLinkUtil.getId(activityLink), paymentRequest))
                            .flatMap(
                                activity -> paymentUnallocateActivityComplete((PaymentActivity) activity, paymentRequest)))
                    .flatMap(commandResult -> publishEventIfUnallocateDeleteMemberRecord(paymentRequest).andThen(
                        Single.just(commandResult))))));
    }

    private Completable publishEventIfUnallocateDeleteMemberRecord(BillingPaymentRequest request) {
        return eventPublisher.publishEventAsync(paymentEventFactory.createDeleteMemberRecordIndexEvent(request));
    }

重点在于commandResult有没有被正确的订阅