Markdown文章标题提取(Java版本)

在处理 Markdown 文章时，有时候我们需要提取文章中的标题，以便生成目录或进行其他处理。本文将介绍如何通过编程的方式提取 Markdown 文章的标题，包括使用正则表达式和简单的字符串处理。

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.ArrayList;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class MarkdownParser {

    public static void main(String[] args) {
        try {
            Path filePath = Paths.get("/文件路径/xxx.md");
            String markdownContent = new String(Files.readAllBytes(filePath));

            List<TOCEntry> toc = extractMarkdownTOC(markdownContent);

            for (TOCEntry entry : toc) {
                System.out.println(entry);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private static List<TOCEntry> extractMarkdownTOC(String markdownContent) {
        List<TOCEntry> toc = new ArrayList<>();
        String[] lines = markdownContent.split("\n");

        Pattern pattern = Pattern.compile("^(#+)\\s+(.*)$");

        for (String line : lines) {
            Matcher matcher = pattern.matcher(line);
            if (matcher.matches()) {
                int level = matcher.group(1).length();
                String title = matcher.group(2).trim();
                toc.add(new TOCEntry(level, title));
            }
//            if (matcher.matches()) {
//                int level = matcher.group(1).length();
//                if (level <= 2) {  // 仅提取一级和二级标题
//                    String title = matcher.group(2).trim();
//                    toc.add(new TOCEntry(level, title));
//                }
//            }
        }

        return toc;
    }

    static class TOCEntry {
        private int level;
        private String title;

        public TOCEntry(int level, String title) {
            this.level = level;
            this.title = title;
        }

        @Override
        public String toString() {
            StringBuilder indentation = new StringBuilder();
            for (int i = 0; i < level - 1; i++) {
                indentation.append("  ");
            }
            return indentation + "- " + title;
        }
    }
}