Question

我有一个.txt文件，最后有一个标记“Home”，我想在Home标记之后取所有文本直到文件结束。但在少数情况下，我有一种情况，在我想要的文本之后，我有几个空行（超过3个）和一些我不需要的文本。所以我需要在Home标记后取所有文本的正则表达式，但如果有空行3或更多它将停止。这是产生问题的.txt文件：

Home
"Empty LINE"
    some text that I need some text that I need some text that I need some text that I need some text that I need some text that I need some text that I need some text that I needsome text that I need

"Empty LINE"

"Empty LINE"

"Empty LINE"

"Empty LINE"

"Empty LINE"






some info that I don't need
some info that I don't need
some info that I don't need
some info that I don't need

这是我的代码：

String content = new String(Files.readAllBytes(Paths.get(FILENAME)));

System.out.println(content);
    String pattern = "Home\\s(.*$)";

      // Create a Pattern object
      Pattern r = Pattern.compile(pattern);

      // Now create matcher object.
      Matcher m = r.matcher(content);
      if (m.find( )) {

         System.out.println("Found value: " + m.group(1) );

      }else {
         System.out.println("NO MATCH");
      }

Answer 1

要获取所有文本，直到获得三个空行或文件末尾，请尝试：

Home\\s(.*?)(?=\\n{3}|$)

Home\s匹配Home字面值，后跟空格\s
随后捕捉群组(.*?)任何角色（非贪婪）
正向前瞻(?=\\n{3}|$)检查后面是否有3个空行\n{3}或文件末尾$

此外，您需要使用DOTALL标记，以便点.也匹配行分隔符。

Pattern.compile(regex, Pattern.DOTALL)

Regex101 Demo

这是一个有效的Java Demo on ideone

Answer 2

以下正则表达式将会这样做：

"(?s)(?:^|\\R)Home\\R(.*?)(?:\\R{3}|$)"

说明：

(?s) - 允许稍后指定的.匹配行终止符（DOTALL标记）。
(?:^|\\R) - 匹配文本的开头或行终止符。请注意，使用\R linebreak matcher以便正确匹配Windows行终止符。
Home\\R - 匹配文字Home和行终止符。
(.*?) - 匹配并capture所需的文字，只要以下匹配模式标识所需文字的结尾（reluctant quantifier）即可结束。
(?:\\R{3}|$) - 匹配3行终结符或文本结尾。

测试

Path path = Paths.get("path/to/file.txt");
String text = new String(Files.readAllBytes(path)); // assume default character encoding

Matcher m = Pattern.compile("(?s)(?:^|\\R)Home\\R(.*?)(?:\\R{3}|$)").matcher(text);
if (m.find())
    System.out.printf("'%s'", m.group(1));
else
    System.out.println("** NOT FOUND **");

文本文件是来自问题的文本的复制/粘贴。

输出

'"Empty LINE"
    some text that I need some text that I need some text that I need some text that I need some text that I need some text that I need some text that I need some text that I needsome text that I need

"Empty LINE"

"Empty LINE"

"Empty LINE"

"Empty LINE"

"Empty LINE"'

Java Regex模式不匹配

2 个答案: