正则表达式回溯直到Java溢出

正则表达式回溯直到Java溢出

我尝试了@Wiktor编写的代码，效果很好

import java.util.regex.Matcher;import java.util.regex.Pattern;public class TestRegex {  public static void main(String[] args) {    String text = "this is a junk linen" +         "n" +         "#ifdef FEATURE n" +         "#endif // end of FEATUREn" +         "n" +         "this is a junk linen" +         "n" +         "#ifdef FEATUREn" +         "n" +         "this is a junk line that should be matched: HOLasduiqwhei & // FEATURE fjfefj #endif // hn" +         "n" +         "#endif FEATUREn" +         "n" +         "this is a junk line";    // this version does not use Pattern.MULTILINE, this should reduce the backtraking    Matcher matcher2 = Pattern.compile("\n#ifdef FEATURE((?:\r?\n(?!#endif (?:// end of )?FEATURE).*)*)\r?\n#endif (?:// end of )?FEATURE").matcher(text);    while (matcher2.find()) {      System.out.println(matcher2.group());    }  }}

这让我认为您的问题是由于输入文件的大小所致。

因此，如果文件太大，则可以将输入实现为

CharSequence

，从而可以包装大文本文件。为什么？因为

Matcher

从a 构建a

Pattern

需要一个

CharSequence

参数。

https://github.com/fge/largetext