高效关联文章与标签：一种优化的关键词匹配方法

{
  "TagA": ["keyword1", "keyword2", "keyword3"],
  "TagB": ["keyword4", "keyword5", "keyword6"]
}

{
  "keyword1": ["TagA"],
  "keyword2": ["TagA"],
  "keyword3": ["TagA"],
  "keyword4": ["TagB"],
  "keyword5": ["TagB"],
  "keyword6": ["TagB"]
}

import java.util.*;

public class ArticleTagger {

    public List<Article> sortByKeyWords(List<Article> articles, Map<String, String[]> keyWords, TagDao tagDao) {
        // 1. 反转映射关系
        Map<String, List<String>> keywordToTags = new HashMap<>();
        for (Map.Entry<String, String[]> entry : keyWords.entrySet()) {
            String tag = entry.getKey();
            for (String keyword : entry.getValue()) {
                keywordToTags.computeIfAbsent(keyword, k -> new ArrayList<>()).add(tag);
            }
        }

        for (Article article : articles) {
            // 2. 统计关键词出现次数
            Map<String, Integer> keywordCounts = new HashMap<>();
            String content = article.getContents();
            for (String keyword : keywordToTags.keySet()) {
                int count = countOccurrences(content, keyword); // 实现 countOccurrences 方法
                if (count > 0) {
                    keywordCounts.put(keyword, count);
                }
            }

            // 3. 过滤低频关键词 (假设阈值为 10)
            keywordCounts.entrySet().removeIf(entry -> entry.getValue() < 10);

            // 4. 获取标签并分配
            Set<String> tagsToAdd = new HashSet<>();
            for (String keyword : keywordCounts.keySet()) {
                List<String> tags = keywordToTags.get(keyword);
                if (tags != null) {
                    tagsToAdd.addAll(tags);
                }
            }

            // 清除旧标签并添加新标签
            article.removeAllTags(Tag.RECHTSGEBIED);
            for (String tagName : tagsToAdd) {
                article.addTag(tagDao.findByName(tagName, Tag.RECHTSGEBIED));
            }
        }

        return articles;
    }

    // 辅助方法：统计字符串中关键词出现的次数
    private int countOccurrences(String text, String keyword) {
        int count = 0;
        int index = 0;
        while ((index = text.indexOf(keyword, index)) != -1) {
            count++;
            index += keyword.length();
        }
        return count;
    }
}

// 假设的 Article 和 Tag 类
class Article {
    private String contents;
    private List<String> tags = new ArrayList<>(); // 简化，假设标签是字符串

    public Article(String contents) {
        this.contents = contents;
    }

    public String getContents() {
        return contents;
    }

    public void addTag(String tag) {
        tags.add(tag);
    }

    public void removeAllTags(String tagType) {
        tags.clear(); // 简化，假设所有标签都是同一类型
    }

    public List<String> getTags() {
        return tags;
    }
}

class Tag {
    public static final String RECHTSGEBIED = "RECHTSGEBIED";
}

// 假设的 TagDao 类
class TagDao {
    public static String findByName(String name, String tagType) {
        // 模拟数据库查询
        return name;
    }
}