将迭代器转换为流

使用 Spliterators.spliterator() 或 Spliterators.spliteratorUnknownSize() 将迭代器转换为流：

 placeholderCopyIterator<String> iterator = Arrays.asList("A", "B", "C").iterator();    
Spliterator<String> spliterator = Spliterators.spliteratorUnknownSize(iterator, 0);
Stream<String> stream = StreamSupport.stream(spliterator, false);