java CompletionStage：为什么在CompletableFuture中定义allOf或anyOf

Question

我有一个使用接口CompletionStage的框架，我很好奇为什么在CompletableFuture中找到的辅助方法anyOf或allOf是在那里定义的

似乎他们应该在接口上而不是在实现上操作

到目前为止，我对CompletionStage界面非常不满意。 是否有其他Java库是CompletionStage兼容的，但有人可以推荐不同的超集接口

或者可能是用其他辅助方法编写的用于CompletionStage的库

Answer 1

如果您只需要一个方法，为类型为CompletionStage的对象提供相同的anyOf和allOf功能，您可以简单地求助于^{}：

public static CompletionStage<Object> anyOf(CompletionStage<?>... css) {
    return CompletableFuture.anyOf(Arrays.stream(css)
        .map(CompletionStage::toCompletableFuture).toArray(CompletableFuture[]::new));
}
public static CompletionStage<Void> allOf(CompletionStage<?>... css) {
    return CompletableFuture.allOf(Arrays.stream(css)
        .map(CompletionStage::toCompletableFuture).toArray(CompletableFuture[]::new));
}

Answer 2

以下是我的想法

/**
 * A class with several helper methods for working with {@link CompletionStage}
 */
public class CompletionStages {


    public static CompletionStage<Object> anyOf(CompletionStage... completionStages) {
        if (completionStages == null) {
            throw new IllegalArgumentException("You must pass a non-null argument for completionStages");
        }
        if (completionStages.length == 0) {
            throw new IllegalArgumentException("You must pass a non-empty argument for completionStages");
        }

        CompletableFuture result = new CompletableFuture();
        for(CompletionStage completionStage : completionStages) {
            completionStage.thenAccept( r -> result.complete(r));
        }
        return result;
    }


    public static CompletionStage<Void> allOf(CompletionStage... completionStages) {
        if (completionStages == null) {
            throw new IllegalArgumentException("You must pass a non-null argument for completionStages");
        }
        if (completionStages.length == 0) {
            throw new IllegalArgumentException("You must pass a non-empty argument for completionStages");
        }

        CompletionStage result = CompletableFuture.completedFuture(null);
        for(int i = 0; i < completionStages.length; i++) {
            CompletionStage curr = completionStages[i];
            result = result.thenAcceptBoth(curr, (o, o2) -> {});
        }
        return result;
    }

}