java/project/ArticleRepository.java

package com.example.datacollect.repository;

import com.example.datacollect.exception.CrawlerException;
import com.example.datacollect.exception.ErrorCode;
import com.example.datacollect.model.Article;
import java.io.*;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

public class ArticleRepository {
    private final List<Article> articles = new ArrayList<>();
    private static final String STORAGE_FILE = "articles.dat";

    public ArticleRepository() {
        loadFromFile();
    }

    public void add(Article article) {
        if (article == null) {
            throw new IllegalArgumentException("Article cannot be null");
        }
        articles.add(article);
        saveToFile();
    }
    
    public void addAll(List<Article> articleList) {
        if (articleList == null) {
            throw new IllegalArgumentException("列表不能为 null");
        }
        for (Article article : articleList) {
            add(article);
        }
    }

    public List<Article> getAll() {
        return Collections.unmodifiableList(articles);
    }

    public int size() {
        return articles.size();
    }

    public void clear() {
        articles.clear();
        saveToFile();
    }

    private void saveToFile() {
        try (ObjectOutputStream oos = new ObjectOutputStream(
                new FileOutputStream(STORAGE_FILE))) {
            oos.writeObject(new ArrayList<>(articles));
        } catch (IOException e) {
            throw new CrawlerException(ErrorCode.FILE_IO_ERROR, "保存数据到文件失败", e);
        }
    }

    @SuppressWarnings("unchecked")
    private void loadFromFile() {
        Path path = Paths.get(STORAGE_FILE);
        if (!Files.exists(path)) {
            return;
        }
        try (ObjectInputStream ois = new ObjectInputStream(
                new FileInputStream(STORAGE_FILE))) {
            List<Article> loaded = (List<Article>) ois.readObject();
            articles.addAll(loaded);
        } catch (IOException | ClassNotFoundException e) {
            throw new CrawlerException(ErrorCode.FILE_IO_ERROR, "从文件加载数据失败", e);
        }
    }

    public void exportToJson(String filename) {
        StringBuilder json = new StringBuilder();
        json.append("[\n");
        for (int i = 0; i < articles.size(); i++) {
            Article a = articles.get(i);
            json.append("  {\n");
            json.append("    \"title\": \"").append(escapeJson(a.getTitle())).append("\",\n");
            json.append("    \"url\": \"").append(escapeJson(a.getUrl())).append("\",\n");
            json.append("    \"content\": \"").append(escapeJson(a.getContent())).append("\"\n");
            json.append("  }");
            if (i < articles.size() - 1) {
                json.append(",");
            }
            json.append("\n");
        }
        json.append("]");
        
        try {
            Files.writeString(Paths.get(filename), json.toString(), StandardCharsets.UTF_8);
        } catch (IOException e) {
            throw new CrawlerException(ErrorCode.FILE_IO_ERROR, "导出JSON失败", e);
        }
    }

    private String escapeJson(String str) {
        if (str == null) {
            return "";
        }
        return str.replace("\\", "\\\\")
                  .replace("\"", "\\\"")
                  .replace("\n", "\\n")
                  .replace("\r", "\\r")
                  .replace("\t", "\\t");
    }
}