java/Project/strategy/DangDangStrategy.java

package strategy;

import model.CrawlResult;
import org.jsoup.nodes.Document;
import org.jsoup.nodes.Element;
import org.jsoup.select.Elements;
import exception.ParseException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

public class DangDangStrategy extends AbstractCrawlStrategy {
    private static final Logger logger = LoggerFactory.getLogger(DangDangStrategy.class);

    private static final String BASE_URL = "http://category.dangdang.com/cp01.01.02.00.00.00.html?page_index=%d";
    private static final String SITE_NAME = "当当网图书搜索";

    @Override
    public String getBaseUrl() {
        return "http://search.dangdang.com/?key=%B6%C1%CA%E9&act=input&page_index=1";
    }

    @Override
    public String getSiteName() {
        return SITE_NAME;
    }

    @Override
    public List<CrawlResult> crawlPage(int page) throws IOException, ParseException {
        List<CrawlResult> results = new ArrayList<>();
        String url = String.format(BASE_URL, page);
        logger.info("正在爬取当当网第 {} 页: {}", page, url);
        Document doc = fetchDocument(url);

        if (doc == null) {
            throw new IOException("无法获取页面: " + url);
        }

        Elements items = doc.select("ul.bigimg li");
        if (items.isEmpty()) {
            items = doc.select(".search_booklist li");
        }
        if (items.isEmpty()) {
            items = doc.select("li[class*=item]");
        }

        if (items.isEmpty()) {
            logger.warn("当当网第 {} 页未找到任何图书列表元素", page);
        }

        for (Element e : items) {
            try {
                CrawlResult result = parseDangDangItem(e);
                if (result != null) {
                    results.add(result);
                }
            } catch (Exception ex) {
                logger.debug("解析当当网图书项失败: {}", ex.getMessage());
            }
        }

        logger.info("当当网第 {} 页解析完成，获取 {} 条数据", page, results.size());
        return results;
    }

    private CrawlResult parseDangDangItem(Element e) {
        String title = "";
        String priceText = "";
        String originalPriceText = "";
        String imageUrl = "";
        String author = "当当网";

        Element titleElem = e.selectFirst("a[title]");
        if (titleElem == null) {
            titleElem = e.selectFirst(".title a");
        }
        if (titleElem == null) {
            titleElem = e.selectFirst(".name a");
        }
        if (titleElem == null) {
            titleElem = e.selectFirst("h4 a");
        }
        if (titleElem == null) {
            titleElem = e.selectFirst(".book-title a");
        }

        if (titleElem != null) {
            title = titleElem.attr("title");
            if (title.isEmpty()) {
                title = titleElem.text();
            }
        }

        if (title == null || title.isEmpty() || title.length() < 3) {
            return null;
        }

        if (title.contains("登录") || title.contains("注册") ||
            title.contains("购物车") || title.contains("帮助") ||
            title.contains("支付") || title.contains("商家") ||
            title.contains("中心") || title.contains("客服") ||
            title.contains("意见") || title.contains("反馈") ||
            title.contains("投诉") || title.contains("我的")) {
            return null;
        }

        Element priceN = e.selectFirst(".price_n");
        if (priceN == null) {
            priceN = e.selectFirst(".price");
        }
        if (priceN == null) {
            priceN = e.selectFirst("span.price");
        }
        if (priceN != null) {
            priceText = priceN.text();
        }
        priceText = priceText.replace("¥", "").replace("元", "").replace("￥", "").trim();

        Element priceO = e.selectFirst(".price_o");
        if (priceO == null) {
            priceO = e.selectFirst(".original-price");
        }
        if (priceO != null) {
            originalPriceText = priceO.text();
        }
        originalPriceText = originalPriceText.replace("¥", "").replace("元", "").replace("￥", "").replace("定价", "").trim();

        Element img = e.selectFirst("img");
        if (img != null) {
            imageUrl = img.attr("src");
            if (imageUrl.isEmpty()) {
                imageUrl = img.attr("data-original");
            }
            if (imageUrl.isEmpty()) {
                imageUrl = img.attr("data-lazy-src");
            }
        }

        Element authorElem = e.selectFirst(".search_book_author a");
        if (authorElem != null) {
            author = authorElem.text();
        }
        if (author.isEmpty()) {
            Element publisherElem = e.selectFirst(".search_book_publisher");
            if (publisherElem != null) {
                author = publisherElem.text();
            }
        }
        if (author.isEmpty() || author.length() > 100) {
            author = "当当网";
        }

        double price = parsePrice(priceText);
        if (price == 0) {
            try {
                String numStr = priceText.replaceAll("[^0-9.]", "");
                if (!numStr.isEmpty()) {
                    price = Double.parseDouble(numStr);
                }
            } catch (NumberFormatException ex) {
                price = 0;
            }
        }

        double originalPrice = parsePrice(originalPriceText);
        if (originalPrice == 0) originalPrice = price * 1.3;
        double discount = parseDiscount(price, originalPrice);

        return new CrawlResult(title, price, originalPrice, discount, imageUrl, author);
    }

    @Override
    public CrawlResult parseItem(Element element) throws ParseException {
        return parseDangDangItem(element);
    }

    @Override
    public int getPageSize() {
        return 30;
    }
}