使用java提供的XPATH处理xml

books.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">XQuery Kick Start</title>
  <author>James McGovern</author>
  <author>Per Bothner</author>
  <author>Kurt Cagle</author>
  <author>James Linn</author>
  <author>Vaidyanathan Nagarajan</author>
  <year>2003</year>
  <price>49.99</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>

基于java提供的API使用XPath处理XML

package com.hqh.stax;

import java.io.InputStream;

import javax.xml.crypto.NodeSetData;
import javax.xml.namespace.QName;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathFactory;

import org.junit.Test;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

public class TestXPath {

	@Test
	public void testXPath() {
		InputStream is = null;
		try {
			// 将xml以流才形式进行加载
			is = Thread.currentThread().getContextClassLoader()
					.getResourceAsStream("books.xml");
			//构建文檔对象
			DocumentBuilder builder = DocumentBuilderFactory.newInstance()
					.newDocumentBuilder();
			// 将xml的输入流解析为一个dom对象
			Document doc = builder.parse(is);
			
			//創建XPath對象
			XPath xpath = XPathFactory.newInstance().newXPath();
			//第一個參數：xpath表達式；第二個參數：文檔源；第三個參數：返回類型
			NodeList nodeList = (NodeList)xpath.evaluate("//book[@category='WEB']", doc, XPathConstants.NODESET);
			
			//輸出屬性為WEB的book所有信息[將輸出該節點下的所有信息]
			for(int i=0;i<nodeList.getLength();i++) {
				Node node = nodeList.item(i);
				System.out.println(node.getTextContent());
			}
			
/*			  結果：
			  XQuery Kick Start
			  James McGovern
			  Per Bothner
			  Kurt Cagle
			  James Linn
			  Vaidyanathan Nagarajan
			  2003
			  49.99


			  Learning XML
			  Erik T. Ray
			  2003
			  39.95*/
			
			//輸出屬性為'WEB'的book的title信息
			for(int i=0;i<nodeList.getLength();i++) {
				Node node = nodeList.item(i);
				Element element = (Element)node;
				Node subNode = element.getElementsByTagName("title").item(0);
				System.out.println(subNode.getTextContent());
			}
			
/*			結果：
 			XQuery Kick Start
			Learning XML*/
			
		} catch (Exception e) {
			e.printStackTrace();
		} finally {

		}

	}
}