我有以下文件格式:

Text1
+ continuation of Text1
+ more continuation of Text1 
Text2
+ continuation of Text2
+ more continuation of Text2
+ even more continuation of Text2

继续由 + 标记.(换行符、加字符、空格作为三个字符串.)续行可以是任意数量的行，包括 0.

Continuations are marked by +. (Newline, plus character, space as a three character string.) Continuations can be any number of lines, including 0.

我想要以下输出(每个都是用 .forEach 打印的一行):

I want the following output (each is a line printed with .forEach):

Text1 continuation of Text1 more continuation of Text1 
Text2 continuation of Text2 more continuation of Text2 even more continuation of Text2

我想只使用 Java 流进行转换，最好使用 Collect.有没有办法优雅地做到这一点?

I would like to use only Java streams to do the conversion, preferably with Collect. Is there a way to do this elegantly?

另一个更现实的例子:

Lorem ipsum dolor sit amet, consectetur 
+ adipiscing elit, sed do eiusmod tempor incididunt 
+ ut labore et dolore magna aliqua. Ut enim ad minim veniam, 
+ quis nostrud exercitation ullamco laboris nisi ut aliquip ex 
+ ea commodo consequat. 
Duis aute irure dolor in reprehenderit in voluptate velit 
+ esse cillum dolore eu fugiat nulla pariatur. Excepteur sint 
+ occaecat cupidatat non proident, sunt in culpa qui officia 
+ deserunt mollit anim id est laborum.

预期的结果是两行:

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. 
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.

推荐答案

在 Java 9 中，你可以使用

In Java 9, you could use

static final Pattern LINE_WITH_CONTINUATION = Pattern.compile("(\V|\R\+)+");

…

try(Scanner s = new Scanner(file)) {
    s.findAll(LINE_WITH_CONTINUATION)
        .map(m -> m.group().replaceAll("\R\+", ""))
        .forEach(System.out::println);
}

由于 Java 8 缺少 Scanner.findAll(Pattern) 方法，您可以添加操作的自定义实现作为解决方法

Since Java 8 lacks the Scanner.findAll(Pattern) method, you may add a custom implementation of the operation as a work-around

public static Stream<MatchResult> findAll(Scanner s, Pattern pattern) {
    return StreamSupport.stream(new Spliterators.AbstractSpliterator<MatchResult>(
            1000, Spliterator.ORDERED|Spliterator.NONNULL) {
        public boolean tryAdvance(Consumer<? super MatchResult> action) {
            if(s.findWithinHorizon(pattern, 0)!=null) {
                action.accept(s.match());
                return true;
            }
            else return false;
        }
    }, false);
}

可以像这样使用

try(Scanner s = new Scanner(file)) {
    findAll(s, LINE_WITH_CONTINUATION)
        .map(m -> m.group().replaceAll("\R\+", ""))
        .forEach(System.out::println);
}

这将使未来的迁移变得容易.

which will make the future migration easy.