如何将回调转换为Promise [英] How to Convert callback to a Promise

问题描述

我正在使用play框架和Apache Kafka。

I am using play framework and Apache Kafka.

我有一个POST方法向Kafka发送消息。 Kafka有一个API方法

I have a POST method which sends a message to Kafka. Kafka has an API method

public java.util.concurrent.Future send（ProducerRecord record ，
回调回调）

其中Javadoc表示

of which the Javadoc says

在确认发送后，异步向主题发送记录并调用提供的
回调。

Asynchronously send a record to a topic and invoke the provided callback when the send has been acknowledged.

我使用play框架公开此功能。我想从Controller方法返回一个 Promise< Result> ，但无法弄清楚如何以非阻塞的方式实现。有人可以帮我解决这个问题吗？

I am exposing this functionality using the play framework. I want to return a Promise<Result> from the Controller method but can't figure out how to implement this in a non-blocking way. Can someone help me with this?

推荐答案

/stackoverflow.com/questions/30956704/java-scala-future-driven-by-a-callback>这是一个。

After some searching found the answer with some help from this one.

以下是代码

RedeemablePromise<Result> promise = RedeemablePromise.empty();

kafkaProducer.send(record, (metadata, ex) -> {
    if (ex != null) {
        promise.failure(ex);
    } else {
        promise.success(created(Json.toJson(new ProduceResult())));
    }
});

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