将AutoCloseable、Iterable类转换为流

Question

StreamSupport.stream()可以从Iterable创建Stream，但是如果该类实现了Iterable和AutoCloseable呢？是否可以将该类转换为Stream，并在try-with-resources块中构造它？

public class NonWorkingExample {
    public static void main(final String[] args) {
        // this won't call MyCursor.close()
        try (Stream<String> stream = StreamSupport.stream(new MyCursor().spliterator(), false)) {
            stream.forEach(System.out::println);
        }
    }

    private static class MyCursor implements AutoCloseable, Iterable<String> {
        public void close() throws Exception {
            System.out.println("close");
        }

        public Iterator<String> iterator() {
            List<String> items = new ArrayList<>();
            items.add("foo");
            items.add("bar");
            items.add("baz");
            return items.iterator();
        }
    }
}

Answer 1

作为stated in the javadoc，BaseStream.onClose()“返回一个具有附加关闭处理程序的等价流”：

public class WorkingExample {
    public static void main(final String[] args) {
        MyCursor cursor = new MyCursor();
        try (Stream<String> stream = StreamSupport.stream(cursor.spliterator(), false)
                                                  .onClose(cursor::close)) {
            stream.forEach(System.out::println);
        }
    }
}

将根据需要调用MyCursor.close()。