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XPath即為XML路徑語言（XML Path Language），它是一種用來確定XML文檔中某部分位置的語言。XPath基于XML的樹狀結構，提供在數據結構樹中找尋節點的能力。起初 XPath 的提出的初衷是將其作為一個通用的、介于XPointer與XSL間的語法模型。但是 XPath 很快的被開發者采用來當作小型查詢語言。

XPathTest.java

復制代碼代碼如下:

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對象
  DocumentBuilder builder = DocumentBuilderFactory.newInstance()
    .newDocumentBuilder();
  Document document = builder.parse(new File("bookstore.xml"));

// 生成XPath對象
XPath xpath = XPathFactory.newInstance().newXPath();

  // 獲取節點值
  String webTitle = (String) xpath.evaluate(
    "/bookstore/book[@category='WEB']/title/text()", document,
    XPathConstants.STRING);
  System.out.println(webTitle);

System.out.println("===========================================================");

  // 獲取節點屬性值
  String webTitleLang = (String) xpath.evaluate(
    "/bookstore/book[@category='WEB']/title/@lang", document,
    XPathConstants.STRING);
  System.out.println(webTitleLang);

System.out.println("===========================================================");

  // 獲取節點對象
  Node bookWeb = (Node) xpath.evaluate(
    "/bookstore/book[@category='WEB']", document,
    XPathConstants.NODE);
  System.out.println(bookWeb.getNodeName());

System.out.println("===========================================================");

  // 獲取節點集合
  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("===========================================================");
}

}

bookstore.xml

復制代碼代碼如下:

	
	<?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>