相关疑难解决方法(0)

使用Java 8 StreamAPI,我想注册一个"完成钩子",类似于:

Stream<String> stream = Stream.of("a", "b", "c");

// additional filters / mappings that I don't control
stream.onComplete((Completion c) -> {
    // This is what I'd like to do:
    closeResources();

    // This might also be useful:
    Optional<Throwable> exception = c.exception();
    exception.ifPresent(e -> throw new ExceptionWrapper(e));
});

我为什么要那么做的原因是因为我想包装在一个资源Stream的API客户端,消费,我想的是Stream,一旦它被消耗自动清理资源.如果可能,那么客户可以致电:

Collected collectedInOneGo =
Utility.something()
       .niceLookingSQLDSL()
       .moreDSLFeatures()
       .stream()
       .filter(a -> true)
       .map(c -> c)
       .collect(collector);

而不是目前所需要的:

try (Stream<X> meh = Utility.something()
                            .niceLookingSQLDSL()
                            .moreDSLFeatures()
                            .stream()) {

    Collected collectedWithUglySyntacticDissonance = …