java使用xpath解析xml示例分享

xpath即为xml路径语言（xml path language），它是一种用来确定xml文档中某部分位置的语言。xpath基于xml的树状结构，提供在数据结构树中找寻节点的能力。起初 xpath 的提出的初衷是将其作为一个通用的、介于xpointer与xsl间的语法模型。但是 xpath 很快的被开发者采用来当作小型查询语言。

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("===========================================================");
 }

}

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>

运行效果