Java Spark : Non-blocking routes/callbacks with CompletableFutures

Question

我必须在 Spark API 实现中调用长时间运行的方法。这些方法返回 CompletableFutures，因此我想通过触发 Spark 在回调中应答客户端请求来释放当前线程。据我所知，Spark 不可能做到这一点，但我想确保我没有忽略任何事情。为了说明这个问题，请参阅下面的小代码示例。

import spark.Spark;
import java.util.concurrent.CompletableFuture;

public class HelloSpark {

    public static void main(String[] args) {
        Spark.get("/what_i_have_to_do", (req, res) -> {
            CompletableFuture<String> f = callToSlowWorker();
            return f.get();
        });

        Spark.get("/what_i_would_like_to_do", (req, res) -> {
            CompletableFuture<String> f = callToSlowWorker();
            f.whenComplete((answer, throwable) -> {
                if(throwable != null){
                    // send error to requesting client
                    res.status(500);
                    res.body(throwable.getMessage());
                } else {
                    // send answer to requesting client
                    res.body(answer);
                }
                // trigger spark to return the response to the client
                // ...?!?
            });
            return null; // obviously not what I want, just to make this sample code compile
        });
    }

    static CompletableFuture<String> callToSlowWorker(){
        return CompletableFuture.supplyAsync(() -> {
            try {
                Thread.sleep(1000);
            } catch (InterruptedException ignored) {
            }
            return "Hello World";
        });
    }
}

Answer 1

SparkJava 目前仅处于阻塞状态，因此您所描述的情况是不可能的。有一个开放enhancement request添加对非阻塞 API 的支持。