通过XPath查询文档信息

通过XPath查询文档信息

[文件] XPathTest.java
package com.hongyuan.test;
 
import java.io.File;
import java.io.IOException;
 
import javax.xml.parsers.DocumentBuilder;
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 org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.SAXException;
 
public class XPathTest {
 
    public static void main(String[] args) throws ParserConfigurationException,
            SAXException, IOException, XPathExpressionException {
 
        // 解析文件,生成document对象
        DocumentBuilder builder = DocumentBuilderFactory.newInstance()
                .newDocumentBuilder();
        Document document = builder.parse(new File("bookstore.xml"));
 
        // 生成XPath对象
        XPath xpath = XPathFactory.newInstance().newXPath();
 
        // 获取节点值
        String webTitle = (String) xpath.evaluate(
                "/bookstore/book[@category='WEB']/title/text()", document,
                XPathConstants.STRING);
        System.out.println(webTitle);
 
        System.out.println("===========================================================");
 
        // 获取节点属性值
        String webTitleLang = (String) xpath.evaluate(
                "/bookstore/book[@category='WEB']/title/@lang", document,
                XPathConstants.STRING);
        System.out.println(webTitleLang);
 
        System.out.println("===========================================================");
 
        // 获取节点对象
        Node bookWeb = (Node) xpath.evaluate(
                "/bookstore/book[@category='WEB']", document,
                XPathConstants.NODE);
        System.out.println(bookWeb.getNodeName());
 
        System.out.println("===========================================================");
 
        // 获取节点集合
        NodeList books = (NodeList) xpath.evaluate("/bookstore/book", document,
                XPathConstants.NODESET);
        for (int i = 0; i < books.getLength(); i++) {
            Node book = books.item(i);
            System.out.println(xpath.evaluate("@category", book,
                    XPathConstants.STRING));
        }
 
        System.out.println("===========================================================");
    }
 
}
[文件] bookstore.xml
<?xml version="1.0" encoding="utf-8" ?>
<bookstore>
    <book category="COOKING">
      <title lang="en">Everyday Italian</title> 
      <author>Giada De Laurentiis</author> 
      <year>2005</year> 
      <price>30.00</price> 
    </book>
    <book category="CHILDREN">
      <title lang="en">Harry Potter</title> 
      <author>J K. Rowling</author> 
      <year>2005</year> 
      <price>29.99</price> 
    </book>
    <book category="WEB">
      <title lang="en">Learning XML</title> 
      <author>Erik T. Ray</author> 
      <year>2003</year> 
      <price>39.95</price> 
    </book>
</bookstore>