Java 웹 크롤러 개발: 웹 페이지 데이터를 자동으로 크롤링하는 방법을 알려줍니다.

public void crawl(String seedUrl) {
    // 初始化URL管理器
    URLManager urlManager = new URLManager();
    urlManager.addUrl(seedUrl);

    // 循环抓取URL队列中的URL
    while(!urlManager.isEmpty()) {
        String url = urlManager.getNextUrl();
        
        // 下载网页
        String html = WebDownloader.downloadHtml(url);
        
        // 解析网页
        WebParser.parseHtml(html);
        
        // 获取解析到的URL，并加入URL队列
        urlManager.addUrls(WebParser.getUrls());
        
        // 存储解析得到的数据
        DataStorage.saveData(WebParser.getData());
    }
}

public static String downloadHtml(String url) {
    StringBuilder html = new StringBuilder();
    try {
        URL targetUrl = new URL(url);
        BufferedReader reader = new BufferedReader(new InputStreamReader(targetUrl.openStream()));
        String line;
        while ((line = reader.readLine()) != null) {
            html.append(line);
        }
        reader.close();
    } catch (Exception e) {
        e.printStackTrace();
    }
    return html.toString();
}

private static List<String> urls = new ArrayList<>();
private static List<String> data = new ArrayList<>();

public static void parseHtml(String html) {
    // 使用正则表达式解析网页，提取URL和数据
    // ...

    // 将解析得到的URL和数据保存到成员变量中
    // ...
}

public static List<String> getUrls() {
    return urls;
}

public static List<String> getData() {
    return data;
}

private Queue<String> urlQueue = new LinkedList<>();
private Set<String> urlSet = new HashSet<>();

public void addUrl(String url) {
    if (!urlSet.contains(url)) {
        urlQueue.offer(url);
        urlSet.add(url);
    }
}

public String getNextUrl() {
    return urlQueue.poll();
}

public void addUrls(List<String> urls) {
    for (String url : urls) {
        addUrl(url);
    }
}

public boolean isEmpty() {
    return urlQueue.isEmpty();
}

public static void saveData(List<String> data) {
    // 存储数据到本地文件或数据库
    // ...
}