Question

这是我的听众

@KafkaListener(topics = ["cartListHashes"])
@SendTo
@Transactional
fun listHashes(token: String): Collection<String> {
    // get id
    return doListHashes(token)
}

private fun doListHashes(token: String): Collection<String> {
    val id = userService.lookupIdSync(token)
    if (id == null) {
        log.info("Cannot get user id with token $token")
        return emptyList()
    }
    return cartRepo.listHashes(id).map { base32.encodeToString(it) }
}

问题是相关ID丢失了。

在回复中找不到相关ID：xxx-要使用请求/回复语义，响应服务器必须在“ correlationId”标头中返回相关ID

Answer 1

事实证明，我不能使用Collection作为返回类型。在MessagingMessageListenerAdapter中：

protected void sendResponse(Object result, String topic, @Nullable Object source, boolean messageReturnType) {
    if (!messageReturnType && topic == null) {
        if (this.logger.isDebugEnabled()) {
            this.logger.debug("No replyTopic to handle the reply: " + result);
        }
    }
    else if (result instanceof Message) {
        this.replyTemplate.send((Message<?>) result);
    }
    else {
        if (result instanceof Collection) {
            ((Collection<V>) result).forEach(v -> {
                if (v instanceof Message) {
                    this.replyTemplate.send((Message<?>) v);
                }
                else {
                    this.replyTemplate.send(topic, v);
                }
            });
        }
        else {
            sendSingleResult(result, topic, source);
        }
    }
}

收集结果将被视为单独的消息。

在我将返回类型修改为Array后，它可以工作。

@KafkaListener(topics = ["cartListHashes"])
@SendTo
@Transactional
fun listHashes(token: String): Array<String> {
    // get id
    return doListHashes(token)
}

private fun doListHashes(token: String): Array<String> {
    val id = userService.lookupIdSync(token)
    if (id == null) {
        log.info("Cannot get user id with token $token")
        return emptyArray()
    }
    return cartRepo.listHashes(id).map { base32.encodeToString(it) }.toTypedArray()
}

将Collection与ReplyingKafkaTemplate一起使用时，关联ID丢失

1 个答案: