How to select data from specific tags in nutch

问题:

I am a newbie in Apache Nutch and I would like to know whether it's possible to crawl selected area of a web page. For instance, select a particular div and crawl contents in that div only. Any help would be appreciated. Thanks!

回答1:

You will have to write a plugin that will extend HtmlParseFilter to achieve your goal.

I reckon you will be doing some of the stuff yourself like parsing the html's specific section, extracting the URLs that you want and add them as outlinks.

HtmlParseFilter implementation: (Code below gives the general idea)

ParseResult filter(Content content, ParseResult parseResult, HTMLMetaTags metaTags, DocumentFragment doc){
    // get html content
    String htmlContent = new String(content.getContent(), StandardCharsets.UTF_8);
    // parse html using jsoup or any other library.
    String url = content.getUrl();
    Parse parse = parseResult.get(url);
    ParseData parseData = parse.getData();
    Outlink[] links = parseData.getOutlinks();
    // modify/select only required outlinks
    // return ParsePesult with modified outlinks
    return parseResult;
}

Hope this will be helpful.

If you are new to plugin, I have written a simple plugin "nutch-fetch-page" which saves html pages and text content on a local drive using HtmlParseFilter interface. You can fork/download and modify the code.