TitleSearcherByXPath.java

package ex5;

import org.w3c.dom.Document;
import org.w3c.dom.NodeList;
import org.xml.sax.SAXException;

import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathExpressionException;
import javax.xml.xpath.XPathFactory;
import java.io.IOException;

public class TitleSearcherByXPath {
    public static void main(String[] args) {
        TitleSearcherByXPath titleSearcherByXPath = new TitleSearcherByXPath();
        titleSearcherByXPath.showItemListByXpath("ちょまど");
    }

    private void showItemListByXpath(String searchWord) {
        try {
            DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance();
            final String RSS_URL = "http://b.hatena.ne.jp/hotentry.rss";
            Document document = documentBuilderFactory.newDocumentBuilder().parse(RSS_URL);
//            Xpathのインスタンス生成
            XPathFactory factory = XPathFactory.newInstance();
            XPath xpath = factory.newXPath();
//            要素を取得
//            String location = "/rss/channel/item";
            NodeList itemNodeList = (NodeList)xpath.evaluate("/RDF/item/title",
                    document, XPathConstants.NODESET);
            // RSS 2.0
            if(itemNodeList.getLength() == 0)
                itemNodeList = (NodeList)xpath.evaluate("/rss/channel/item/title",
                        document, XPathConstants.NODESET);

            for(int i = 0; i < itemNodeList.getLength(); i++) {
                String title = itemNodeList.item(i).getFirstChild().getNodeValue();
                if (title.contains(searchWord)) {
                    System.out.println(title);
                }
            }
        } catch (IOException | XPathExpressionException | SAXException | ParserConfigurationException e) {
            e.printStackTrace();
        }
    }

}