android - 使用正则表达式从网页捕获图像

Question

我正在编写一个简单的程序来从网页中捕获图像资源。 html 中的图像项如下所示:

CASE1:<img src="http://www.aaa.com/bbb.jpg" alt="title bbb" width="350" height="385"/>

或

CASE2:<img alt="title ccc" src="http://www.ddd.com/bbb.jpg"  width="123" height="456"/>

我知道如何分别处理这两种情况，以第一种为例:

    String CAPTURE = "<img(?:.*)src=\"http://(.*)\\.jpg\"(?:.*)alt=\"(.*?)\"(?:.*)/>";
    DefaultHttpClient client = new DefaultHttpClient();
    BasicHttpContext context = new BasicHttpContext();
    Scanner scanner = new Scanner(client
            .execute(new HttpGet(uri), context)
            .getEntity().getContent());
    Pattern pattern = Pattern.compile(CAPTURE);
    while (scanner.findWithinHorizon(pattern, 0) != null) {
        MatchResult r = scanner.match();
        String imageUrl = "http://" +r.group(1)+".jpg";
        String imageTitle = r.group(2);
        //Do something with the image
   }

问题是如何编写正确的模式以从包含 CASE1 和 CASE2 的网页源代码中获取所有图像项？我只想扫描页面一次。

Answer 1

使用jsoup

import org.jsoup.Jsoup;
import org.jsoup.nodes.Document;
import org.jsoup.nodes.Element;
import org.jsoup.select.Elements;
...

 Document doc;
 String userAgent = "Mozilla/5.0 (Windows NT 6.1; WOW64; rv:28.0) Gecko/20100101 Firefox/28.0";
try {

    // need http protocol
    doc = Jsoup.connect("http://domain.tld/images.html").userAgent(userAgent).get();

    // get all images
    Elements images = doc.select("img");
    for (Element image: images) {

        // get the values from img attribute (src & alt)
        System.out.println("\nImage: " + image.attr("src"));
        System.out.println("Alt : " + image.attr("alt"));

    }

} catch (IOException e) {
    e.printStackTrace();
}

Jsoup, a HTML parser, its “jquery-like” and “regex” selector syntax is very easy to use and flexible enough to get whatever you want.