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用DOM解析XML ,用xpath快速查询XML节点

时间:2018-11-11 19:12:14      阅读:180      评论:0      收藏:0      [点我收藏+]

标签:内容   sax   .com   and   void   sql语句   expand   form   handle   

XPath是一种快速查询xml节点和属性的一种语言,Xpath和xml的关系就像是sql语句和数据库的关系。用sql语句可以从数据库中快速查询出东西同样的用xPath也可以快速的从xml中查询出东西。

下面的示例演示了怎么用jdk自带的rt.jar完成dom解析

代码如下:

test.xml的代码如下:

<?xml version="1.0" encoding="UTF-8" ?>

<inventory>
    <book year="2012">
        <title>菜根谭</title>
        <author>洪应明</author>
        <dynasty>明朝</dynasty>
        <price>38</price>
    </book>
    <book year="2013">
        <title>曾国藩家书</title>
        <author>曾国藩</author>
        <dynasty>清朝</dynasty>
        <price>89</price>
    </book>
    <book year="2014">
        <title>高等代数</title>
        <author>丘维声</author>
        <dynasty>中华人民共和国</dynasty>
        <price>86</price>
    </book>
</inventory>

ParseXmlTest的代码如下:

package com.timo.xml;

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

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.xpath.*;
import java.io.File;

/**
 * @author Abraham Qin
 * @since 2018/11/11
 */
public class ParseXmlTest {
  //查询价格大于40的书的标题的内容
private static final String XPath_EXPRESSION = "//book[price>40]/title/text()"; public static void main(String[] args) throws Exception { DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance(); //开启验证: documentBuilderFactory.setValidating(true); documentBuilderFactory.setNamespaceAware(false); documentBuilderFactory.setIgnoringComments(true); documentBuilderFactory.setIgnoringElementContentWhitespace(true); documentBuilderFactory.setCoalescing(false); documentBuilderFactory.setExpandEntityReferences(true); DocumentBuilder documentBuilder = documentBuilderFactory.newDocumentBuilder(); //设置异常处理: documentBuilder.setErrorHandler(new ErrorHandler() { @Override public void warning(SAXParseException exception) throws SAXException { System.out.println("warn:" + exception.getMessage()); } @Override public void error(SAXParseException exception) throws SAXException { System.out.println("error:" + exception.getMessage()); } @Override public void fatalError(SAXParseException exception) throws SAXException { System.out.println("fatalError:" + exception.getMessage()); } }); //将test.xml加载到一个Document的对象中: String filePath = "E:\\mybatis-indepth-research\\mybatis-3\\src\\main\\java\\com\\timo\\xml\\test.xml"; Document document = documentBuilder.parse(new File(filePath)); //查询author为洪应明的title: processParseXmlWithXpath(document,XPath_EXPRESSION ); } private static void processParseXmlWithXpath(Document document, String xPathExpression) throws Exception { //创建XPathFactory: XPathFactory xPathFactory = XPathFactory.newInstance(); XPath xPath = xPathFactory.newXPath(); XPathExpression expression = xPath.compile(xPathExpression); Object result = expression.evaluate(document, XPathConstants.NODESET); if (result instanceof NodeList) { NodeList nodes = (NodeList) result; for (int i = 0; i < nodes.getLength(); i++) { System.out.println(String.format("%s=%s", nodes.item(i).getNodeName(), nodes.item(i).getNodeValue())); } } } }

 

用DOM解析XML ,用xpath快速查询XML节点

标签:内容   sax   .com   and   void   sql语句   expand   form   handle   

原文地址:https://www.cnblogs.com/1540340840qls/p/9942861.html

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